Hybrid Certification Criteria (HCC) for Transport Category Hybrid 

Airships

Document Number: 1008D0122

Revision: C

Date: January 31, 2013

Prepared by:

Lockheed Martin Aeronautics Company

1011 Lockheed Way

Palmdale, CA 93599
Document Number: 1008D0122

Revision: C

Page ii of xiv

REVISION HISTORY

Revision Date Change Description Originator DOORS Version

N/C 08/01/2012 Initial Release Kent Trenkle 0.5

A 08/28/2012 Removed copyright and minor 

grammatical corrections

Kent Trenkle 0.6

B 01/25/2013 Incorporated FAA Letter No. 

100S-12-30 Nov 29, 2012 

Comments

Kent Trenkle 0.7

C 01/31/2013 Incorporated changes from 

FAA Preliminary Type 

Certification Meeting

Kent Trenkle 1.0
Document Number: 1008D0122

Revision: C

Page iii of xiv

Note: Whenever a CFR part or its Appendix is referenced in this criteria then all immediate and 

subsequent sub-references (i.e.: references within references) are also included. Amendment 

levels for CFR references are those in effect upon the date of this document (see title page) 

unless otherwise specified.

Table of Contents

Subpart A - General...................................................................................................................... 1

HCC.1 Applicability................................................................................................................. 1

Subpart B - Flight ......................................................................................................................... 2

GENERAL................................................................................................................................... 2

HCC.21 Proof of compliance ................................................................................................... 2

HCC.23 Load distribution limits.............................................................................................. 2

HCC.25 Mass limits................................................................................................................. 3

HCC.27 Center of gravity limits.............................................................................................. 3

HCC.29 Empty mass and corresponding center of gravity...................................................... 3

HCC.31 Removable ballast...................................................................................................... 4

HCC.33 Propeller speed and pitch limits................................................................................. 4

PERFORMANCE........................................................................................................................ 5

HCC.45 General....................................................................................................................... 5

HCC.49 Performance at minimum operating speed................................................................. 6

HCC.51 Takeoff....................................................................................................................... 6

HCC.65 Climb: all engines operating ...................................................................................... 8

HCC.67 Climb: critical engine inoperative.............................................................................. 8

HCC.68 En-route flight path .................................................................................................... 9

HCC.75 Landing ...................................................................................................................... 9

HCC.76 Engine failure........................................................................................................... 10

HCC.77 Balked landing ......................................................................................................... 10

HCC.80 Loading/Unloading .................................................................................................. 10

FLIGHT CHARACTERISTICS................................................................................................ 11

HCC.141 General................................................................................................................... 11

CONTROLLABILITY AND MANEUVERABILITY............................................................. 11

HCC.143 General................................................................................................................... 11

HCC.145 Longitudinal control............................................................................................... 12

HCC.147 Directional control ................................................................................................. 12

HCC.149 Minimum control speed ......................................................................................... 12

HCC.150 Minimum aerodynamic control speed.................................................................... 13

HCC.153 Control during landings ......................................................................................... 13

TRIM ......................................................................................................................................... 13

HCC.161 Trim........................................................................................................................ 13

STABILITY............................................................................................................................... 13

HCC.171 General................................................................................................................... 13

HCC.181 Dynamic stability ................................................................................................... 13

MISCELLANEOUS FLIGHT REQUIREMENTS................................................................... 14
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HCC.201 Loss of aerodynamic lift demonstration................................................................. 14

HCC.203 Loss of aerodynamic lift characteristics................................................................. 14

HCC.207 Loss of aerodynamic lift warning .......................................................................... 14

HCC.231 Operations on Water .............................................................................................. 14

HCC.237 Wind velocities ...................................................................................................... 14

HCC.251 Vibration and buffeting.......................................................................................... 15

HCC.253 Envelope pressure and distortion ........................................................................... 15

HCC.255 Ground handling characteristics............................................................................. 15

HCC.261 Flight in rough air .................................................................................................. 15

Subpart C - Structure................................................................................................................. 16

GENERAL................................................................................................................................. 16

HCC.301 Loads...................................................................................................................... 16

HCC.303 Factors of safety..................................................................................................... 16

HCC.305 Strength and deformation....................................................................................... 16

HCC.307 Proof of structure ................................................................................................... 16

HCC.309 Design mass ........................................................................................................... 17

HCC.311 Design airspeeds .................................................................................................... 17

FLIGHT LOADS....................................................................................................................... 18

HCC.321 General................................................................................................................... 18

HCC.333 Design maneuvering loads..................................................................................... 18

HCC.341 Gust and turbulence loads...................................................................................... 19

HCC.361 Engine and propeller and APU torque ................................................................... 20

HCC.363 Side load on engine and APU mounts ................................................................... 21

HCC.367 Unsymmetrical loads due to engine failure............................................................ 21

HCC.371 Gyroscopic loads.................................................................................................... 22

CONTROL SURFACE AND SYSTEM LOADS..................................................................... 22

HCC.391 Control surface loads: general ............................................................................... 22

HCC.395 Control system ....................................................................................................... 22

HCC.397 Control system loads.............................................................................................. 22

HCC.399 Dual control system ............................................................................................... 23

HCC.405 Secondary control system ...................................................................................... 23

HCC.407 Trim tabs effects..................................................................................................... 23

HCC.409 Tabs........................................................................................................................ 23

HCC.411 Supplementary conditions for control surfaces...................................................... 23

HCC.415 Tail-to-wind loads.................................................................................................. 23

GROUND LOADS.................................................................................................................... 24

HCC.471 General................................................................................................................... 24

HCC.473 Ground load conditions and assumptions .............................................................. 24

HCC.479 ACLS loading condition ........................................................................................ 25

HCC.481 Mooring conditions................................................................................................ 25

OTHER LOADS........................................................................................................................ 26

HCC.505 Precipitation conditions.......................................................................................... 26

HCC.507 Jacking loads.......................................................................................................... 26

HCC.509 Servicing access loads............................................................................................ 26

EMERGENCY LANDING CONDITIONS.............................................................................. 26
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HCC.561 General................................................................................................................... 26

FATIGUE EVALUATION ....................................................................................................... 27

HCC.571 General................................................................................................................... 27

HCC.573 Damage tolerance and fatigue evaluation .............................................................. 28

LIGHTNING PROTECTION ................................................................................................... 31

HCC.581 Lightning protection............................................................................................... 31

Subpart D - Design and Construction....................................................................................... 32

GENERAL................................................................................................................................. 32

HCC.601 General................................................................................................................... 32

HCC.603 Materials................................................................................................................. 32

HCC.605 Fabrication methods............................................................................................... 32

HCC.607 Fasteners................................................................................................................. 32

HCC.609 Protection of structure............................................................................................ 32

HCC.611 Accessibility provisions......................................................................................... 33

HCC.613 Material strength properties and design values...................................................... 33

HCC.619 Special factors........................................................................................................ 33

HCC.621 Casting factors........................................................................................................ 34

HCC.623 Bearing factors....................................................................................................... 35

HCC.625 Fitting factors......................................................................................................... 35

HCC.628 Rope, wire, cable and chain factors ....................................................................... 36

HCC.631 Birdstrike................................................................................................................ 36

CONTROL SURFACES ........................................................................................................... 36

HCC.651 Proof of strength .................................................................................................... 36

HCC.655 Installation.............................................................................................................. 36

HCC.657 Hinges.................................................................................................................... 36

HCC.659 Mass balance.......................................................................................................... 37

CONTROL SYSTEMS ............................................................................................................. 37

HCC.671 General................................................................................................................... 37

HCC.672 Stability augmentation and automatic and power-operated systems..................... 38

HCC.675 Stops....................................................................................................................... 38

HCC.677 Trim Systems ......................................................................................................... 38

HCC.679 Control system gust locks...................................................................................... 39

HCC.681 Limit load static tests ............................................................................................. 39

HCC.683 Operation tests........................................................................................................ 39

HCC.685 Control system details............................................................................................ 40

HCC.693 Joints ...................................................................................................................... 40

HCC.697 Lift and Drag Devices, Controls............................................................................ 40

HCC.699 Lift and Drag Device Indicator.............................................................................. 40

AIR CUSHION LANDING SYSTEM (ACLS)........................................................................ 40

HCC.721 General................................................................................................................... 40

HCC.723 Shock absorption tests............................................................................................ 41

HCC.729 Retraction mechanism............................................................................................ 41

PERSONNEL AND CARGO ACCOMMODATIONS............................................................ 42

HCC.771 Pilot compartment.................................................................................................. 42

HCC.772 Flight crew compartment doors ............................................................................. 43
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HCC.773 Pilot compartment view ......................................................................................... 43

HCC.775 Windshields and windows ..................................................................................... 43

HCC.777 Cockpit controls..................................................................................................... 44

HCC.779 Motion and effect of cockpit controls.................................................................... 44

HCC.783 Doors...................................................................................................................... 44

HCC.784 Passenger compartment windows.......................................................................... 46

HCC.785 Seats, berths, safety belts and harnesses................................................................ 46

HCC.786 Areas accessible during flight................................................................................ 48

HCC.787 Baggage and cargo compartment........................................................................... 48

HCC.789 Retention of items of mass in passenger and crew compartments and galleys...... 48

HCC.791 Passenger information signs and placards ............................................................. 49

HCC.793 Floor surfaces......................................................................................................... 49

HCC.801 Ditching.................................................................................................................. 49

HCC.803 Emergency evacuation ........................................................................................... 50

HCC.807 Emergency exits..................................................................................................... 50

HCC.810 Emergency egress assist means and escape routes ................................................ 52

HCC.811 Emergency exit marking ........................................................................................ 52

HCC.812 Emergency lighting................................................................................................ 53

HCC.813 Emergency exit access........................................................................................... 55

HCC.815 Width of aisle ......................................................................................................... 55

HCC.831 Ventilation.............................................................................................................. 56

FIRE PROTECTION EVALUATION...................................................................................... 57

HCC.833 Combustion heating systems.................................................................................. 57

HCC.851 Fire extinguishers................................................................................................... 57

HCC.853 Compartment interiors ........................................................................................... 58

HCC.854 Lavatory fire protection ......................................................................................... 59

HCC.855 Cargo or baggage compartments............................................................................ 59

HCC.856 Thermal/Acoustic Insulation materials.................................................................. 60

HCC.857 Cargo compartment classification.......................................................................... 60

HCC.858 Cargo compartment fire detection systems............................................................ 61

HCC.859 Combustion heater fire protection.......................................................................... 61

HCC.863 Flammable fluid fire protection ............................................................................. 63

HCC.865 Fire protection of flight controls, engine mounts and other flight structure .......... 64

HCC.869 Fire protection: systems......................................................................................... 64

MISCELLANEOUS.................................................................................................................. 64

HCC.871 Leveling means...................................................................................................... 64

HCC.875 Protection near propellers ...................................................................................... 65

AIRSHIP SPECIFICS ............................................................................................................... 65

HCC.883 Non-rigid Airship envelope ................................................................................... 65

HCC.887 Lifting gas pressure system.................................................................................... 66

HCC.889 Ground handling provisions................................................................................... 68

HCC.891 Flutter..................................................................................................................... 68

HCC.893 Lifting gas.............................................................................................................. 68

HCC.897 External load means of attachment ........................................................................ 68

HCC.898 Jettisonable external loads ..................................................................................... 68
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HCC.899 Hoists and suspended loads ................................................................................... 69

Subpart E - Powerplant (Thrusters) ......................................................................................... 71

GENERAL................................................................................................................................. 71

HCC.901 Installation.............................................................................................................. 71

HCC.903 Engines................................................................................................................... 71

HCC.905 Propellers ............................................................................................................... 73

HCC.907 Vibration ................................................................................................................ 73

HCC.908 Cooling fans........................................................................................................... 74

HCC.909 Turbochargers........................................................................................................ 74

HCC.917 Thruster drive system............................................................................................. 74

HCC.918 Shafting critical speed............................................................................................ 75

HCC.919 Shafting joints........................................................................................................ 75

HCC.921 Thruster brake ........................................................................................................ 75

HCC.923 Thruster drive system and control mechanism tests .............................................. 75

HCC.924 Additional tests ...................................................................................................... 77

HCC.925 Propeller clearance................................................................................................. 77

HCC.929 Propeller de-icing................................................................................................... 78

HCC.933 Reversing systems.................................................................................................. 78

HCC.937 Turbopropeller - drag limiting systems.................................................................. 78

HCC.939 Powerplant operating characteristics ..................................................................... 78

HCC.943 Negative acceleration............................................................................................. 79

HCC.945 Powerplant Installation – One cylinder inoperative............................................... 79

HCC.947 Powerplant Installation – High Energy Engine Fragments.................................... 79

FUEL SYSTEM ........................................................................................................................ 79

HCC.951 General................................................................................................................... 79

HCC.952 Fuel system analysis and test ................................................................................. 80

HCC.953 Fuel system independence ..................................................................................... 80

HCC.954 Fuel System lightning protection ........................................................................... 80

HCC.955 Fuel Flow ............................................................................................................... 80

HCC.957 Flow between interconnected tanks....................................................................... 81

HCC.959 Unusable fuel supply.............................................................................................. 81

HCC.961 Fuel system hot weather operation......................................................................... 81

HCC.963 Fuel tanks: general ................................................................................................. 82

HCC.965 Fuel tank tests......................................................................................................... 82

HCC.967 Fuel tank installation.............................................................................................. 84

HCC.969 Fuel tank expansion space...................................................................................... 84

HCC.971 Fuel tank sump....................................................................................................... 84

HCC.973 Fuel tank filler connection ..................................................................................... 85

HCC.975 Fuel tank vents and carburetor vapor vents ........................................................... 85

HCC.977 Fuel tank outlet ...................................................................................................... 86

HCC.979 Pressure fueling system.......................................................................................... 86

HCC.981 Fuel tank ignition prevention ................................................................................. 87

HCC.983 Fuel Tanks Temperature Limits............................................................................. 87

FUEL SYSTEM COMPONENTS ............................................................................................ 88

HCC.991 Fuel pumps............................................................................................................. 88
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HCC.993 Fuel system lines and fittings................................................................................. 88

HCC.994 Fuel system components........................................................................................ 88

HCC.995 Fuel valves ............................................................................................................. 88

HCC.997 Fuel strainer or filter .............................................................................................. 89

HCC.999 Fuel system drains.................................................................................................. 89

HCC.1001 Fuel jettisoning system ........................................................................................ 89

OIL SYSTEM............................................................................................................................ 90

HCC.1011 General................................................................................................................. 90

HCC.1013 Oil tanks............................................................................................................... 90

HCC.1015 Oil tank tests......................................................................................................... 91

HCC.1017 Oil lines and fittings............................................................................................. 91

HCC.1019 Oil strainer or filter .............................................................................................. 92

HCC.1021 Oil system drains.................................................................................................. 92

HCC.1023 Oil radiators.......................................................................................................... 92

HCC.1025 Oil valves ............................................................................................................. 93

HCC.1027 Propeller feathering system.................................................................................. 93

COOLING ................................................................................................................................. 93

HCC.1041 General................................................................................................................. 93

HCC.1043 Cooling tests......................................................................................................... 93

HCC.1045 Cooling test procedures........................................................................................ 94

LIQUID COOLING .................................................................................................................. 95

HCC.1061 Installation............................................................................................................ 95

HCC.1063 Coolant tank tests................................................................................................. 96

INDUCTION SYSTEM ............................................................................................................ 97

HCC.1091 Air intake.............................................................................................................. 97

HCC.1093 Air intake system de-icing and anti-icing provisions........................................... 97

HCC.1101 Carburetor air preheater design............................................................................ 99

HCC.1103 Induction system ducts......................................................................................... 99

HCC.1105 Air intake system screens..................................................................................... 99

HCC.1107 Inter-coolers and after-coolers........................................................................... 100

HCC.1108 Induction system filters...................................................................................... 100

HCC.1109 Turbocharger bleed air system........................................................................... 100

HCC.1111 Turbine engine bleed-air system........................................................................ 100

EXHAUST SYSTEM.............................................................................................................. 100

HCC.1121 General............................................................................................................... 100

HCC.1123 Exhaust piping.................................................................................................... 101

HCC.1125 Exhaust heat exchangers.................................................................................... 101

POWERPLANT CONTROLS AND ACCESSORIES........................................................... 101

HCC.1141 Powerplant controls: general.............................................................................. 101

HCC.1143 Engine controls .................................................................................................. 102

HCC.1145 Ignition switches................................................................................................ 102

HCC.1147 Mixture controls................................................................................................. 103

HCC.1149 Propeller speed and pitch controls..................................................................... 103

HCC.1153 Propeller feathering controls.............................................................................. 103

HCC.1157 Carburetor air temperature controls................................................................... 103
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HCC.1161 Fuel jettisoning system controls......................................................................... 103

HCC.1163 Powerplant accessories ...................................................................................... 103

HCC.1165 Engine ignition systems..................................................................................... 104

HCC.1166 FADEC Controlled Engines............................................................................... 105

HCC.1167 Vectored thrust controls..................................................................................... 105

POWERPLANT FIRE PROTECTION................................................................................... 106

HCC.1181 Designated fire zones: regions included ............................................................ 106

HCC.1182 Nacelle areas behind firewalls, and engine pod attaching structures containing 

flammable fluid lines............................................................................................................ 106

HCC.1183 Flammable fluid-carrying components.............................................................. 106

HCC.1185 Flammable fluids ............................................................................................... 107

HCC.1187 Drainage and ventilation of fire zones............................................................... 107

HCC.1188 Ventilation.......................................................................................................... 107

HCC.1189 Shut-off means................................................................................................... 108

HCC.1191 Firewalls............................................................................................................. 108

HCC.1192 Engine accessory compartment diaphragm........................................................ 109

HCC.1193 Engine cowling .................................................................................................. 109

HCC.1195 Fire extinguishing systems................................................................................. 109

HCC.1197 Fire extinguishing agents................................................................................... 110

HCC.1199 Extinguishing agent containers.......................................................................... 110

HCC.1201 Fire extinguishing system materials................................................................... 111

HCC.1203 Fire detector system ........................................................................................... 111

HCC.1205 Vectored thrust................................................................................................... 112

HCC.1207 Compliance ........................................................................................................ 112

Subpart F - Equipment............................................................................................................. 113

GENERAL............................................................................................................................... 113

HCC.1301 Function and installation.................................................................................... 113

HCC.1302 Installed systems and equipment for use by the flight crew .............................. 113

HCC.1303 Flight and navigation instruments...................................................................... 114

HCC.1305 Powerplant instruments...................................................................................... 114

HCC.1306 Miscellaneous equipment instruments............................................................... 117

HCC.1307 Miscellaneous equipment................................................................................... 117

HCC.1309 Equipment, systems, and installations ............................................................... 118

HCC.1310 Power source capacity and distribution ............................................................. 119

HCC.1316 Electrical and electronic system lightning protection ........................................ 119

HCC.1317 High-Intensity Radiated Fields (HIRF) Protection ............................................ 119

INSTRUMENTS: INSTALLATION...................................................................................... 120

HCC.1321 Arrangement and visibility................................................................................. 120

HCC.1322 Warning, caution and advisory lights ................................................................ 121

HCC.1323 Airspeed indicating system ................................................................................ 121

HCC.1325 Static pressure systems....................................................................................... 122

HCC.1326 Pitot heat indication systems.............................................................................. 123

HCC.1327 Magnetic direction indicator.............................................................................. 123

HCC.1329 Automatic pilot system ...................................................................................... 123

HCC.1330 Electronic flight instrument system (EFIS) ....................................................... 124
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HCC.1331 Instruments using a power supply...................................................................... 124

HCC.1333 Instrument systems............................................................................................. 124

HCC.1335 Flight director systems....................................................................................... 125

HCC.1337 Powerplant instruments...................................................................................... 125

ELECTRICAL SYSTEMS AND EQUIPMENT.................................................................... 126

HCC.1351 General............................................................................................................... 126

HCC.1353 Electrical equipment and installations ............................................................... 127

HCC.1355 Distribution system ............................................................................................ 128

HCC.1357 Circuit protective devices................................................................................... 129

HCC.1360 Precautions against injury .................................................................................. 129

HCC.1361 Master switch arrangement ................................................................................ 129

HCC.1362 Electricity supplies for emergency conditions................................................... 130

HCC.1363 Electrical system tests........................................................................................ 130

HCC.1367 Switches............................................................................................................. 130

LIGHTS................................................................................................................................... 130

HCC.1381 Instrument lights ................................................................................................ 130

HCC.1383 Ground proximity and landing lights................................................................. 131

HCC.1385 Position light system installation ....................................................................... 131

HCC.1387 Position light system dihedral angles................................................................. 132

HCC.1389 Position light distribution and intensities........................................................... 132

HCC.1391 Minimum intensities in the horizontal plane of bow, forward, rearward and stern 

position lights....................................................................................................................... 133

HCC.1393 Minimum intensities in any vertical plane of bow, forward, rearward and stern 

position lights....................................................................................................................... 133

HCC.1395 Maximum intensities in overlapping beams of bow and forward, forward and 

stern, respectively rearward and stern position light............................................................ 133

HCC.1397 Color specifications............................................................................................ 134

HCC.1401 Anticollision light system .................................................................................. 134

SAFETY EQUIPMENT.......................................................................................................... 135

HCC.1411 General............................................................................................................... 135

HCC.1413 Safety belts......................................................................................................... 136

HCC.1414 Electrical bonding and protection against static electricity ............................... 136

HCC.1415 Ditching equipment............................................................................................ 136

HCC.1417 Icing Detection................................................................................................... 137

HCC.1419 Ice and snow protection ..................................................................................... 137

HCC.1421 Megaphones....................................................................................................... 138

HCC.1422 Lifting gas detector and alarm ........................................................................... 138

MISCELLANEOUS EQUIPMENT........................................................................................ 138

HCC.1423 Public address system ........................................................................................ 138

HCC.1431 Electronic equipment ......................................................................................... 139

HCC.1435 Hydraulic systems.............................................................................................. 139

HCC.1436 Pneumatic systems - high pressure .................................................................... 141

HCC.1437 Engine-driven accessories.................................................................................. 143

HCC.1438 Pneumatic systems- low pressure ...................................................................... 143

HCC.1439 Protective breathing equipment ......................................................................... 143
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HCC.1455 Draining of fluids subject to freezing ................................................................ 144

HCC.1457 Cockpit voice recorders ..................................................................................... 144

HCC.1459 Flight recorders.................................................................................................. 145

HCC.1461 Equipment containing high energy rotors.......................................................... 146

HCC.1499 Domestic services and appliances...................................................................... 147

Subpart G - Operating Limitations and Information ........................................................... 148

GENERAL............................................................................................................................... 148

HCC.1501 General............................................................................................................... 148

OPERATING LIMITATIONS................................................................................................ 148

HCC.1503 Airspeed limitations: general ............................................................................. 148

HCC.1505 Maximum operating speed limits....................................................................... 148

HCC.1515 ACLS speeds...................................................................................................... 148

HCC.1516 Other speed limitations ...................................................................................... 148

HCC.1519 Mass and center of gravity and mass distribution.............................................. 148

HCC.1521 Powerplant limitations ....................................................................................... 148

HCC.1522 Auxiliary power unit limitations........................................................................ 150

HCC.1523 Minimum flight crew ......................................................................................... 150

HCC.1524 Systems and equipment limitations.................................................................... 150

HCC.1525 Kinds of operation.............................................................................................. 150

HCC.1526 Maximum rates of climb and descent ................................................................ 150

HCC.1527 Ambient air temperature and operating altitude ................................................ 150

HCC.1528 Envelope, lifting gas and ballonet pressures...................................................... 150

HCC.1529 Instructions for continued airworthiness............................................................ 150

HCC.1530 Engine or propeller vectoring ............................................................................ 151

HCC.1533 Additional operating limits ................................................................................ 151

MARKINGS AND PLACARDS ............................................................................................ 151

HCC.1541 General............................................................................................................... 151

HCC.1543 Instrument markings: general............................................................................. 151

HCC.1544 Operating pressure limitations........................................................................... 151

HCC.1545 Airspeed limitation information......................................................................... 151

HCC.1547 Magnetic direction indicator.............................................................................. 151

HCC.1549 Powerplant and APU instruments...................................................................... 152

HCC.1551 Oil quantity indicator ......................................................................................... 152

HCC.1553 Fuel quantity indicator ....................................................................................... 152

HCC.1555 Control markings ............................................................................................... 152

HCC.1557 Miscellaneous markings and placards................................................................ 153

HCC.1559 Operating limitations placard............................................................................. 154

HCC.1561 Safety equipment................................................................................................ 154

HCC.1563 Airspeed/ Altitude/ Attitude placard .................................................................. 154

AIRSHIP FLIGHT MANUAL................................................................................................ 154

HCC.1581 General............................................................................................................... 154

HCC.1583 Operating limitations.......................................................................................... 155

HCC.1585 Operating procedures......................................................................................... 156

HCC.1587 Performance information ................................................................................... 158

HCC.1589 Loading information .......................................................................................... 160
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HYBRID FUNCTION AND RELIABILITY TESTING ....................................................... 160

HCC.2135 Function and reliability testing .......................................................................... 160

Subpart J - Powerplant (Auxiliary Power Unit (APU)) ........................................................ 161

GENERAL............................................................................................................................... 161

HCC.J901 Installation .......................................................................................................... 161

HCC.J903 Engines............................................................................................................... 161

HCC.J907 Vibration............................................................................................................. 162

HCC.J908 Cooling fans........................................................................................................ 162

HCC.J909 Turbochargers..................................................................................................... 163

HCC.J917 APU drive system............................................................................................... 163

HCC.J918 Shafting critical speed ........................................................................................ 163

HCC.J919 Shafting joints..................................................................................................... 164

HCC.J923 APU drive system and control mechanism tests ................................................ 164

HCC.J939 Powerplant operating characteristics.................................................................. 165

HCC.J943 Negative acceleration ......................................................................................... 166

FUEL SYSTEM ...................................................................................................................... 166

HCC.J951 General ............................................................................................................... 166

HCC.J952 Fuel system analysis and test.............................................................................. 166

HCC.J953 Fuel system independence.................................................................................. 167

HCC.J954 Fuel System lightning protection........................................................................ 167

HCC.J955 Fuel Flow............................................................................................................ 167

HCC.J961 Fuel system hot weather operation ..................................................................... 167

HCC.J975 Carburetor vapor vents....................................................................................... 168

HCC.J977 Fuel tank outlet................................................................................................... 168

FUEL SYSTEM COMPONENTS .......................................................................................... 169

HCC.J991 Fuel pumps ......................................................................................................... 169

HCC.J993 Fuel system lines and fittings............................................................................. 169

HCC.J994 Fuel system components .................................................................................... 169

HCC.J995 Fuel valves.......................................................................................................... 169

HCC.J997 Fuel strainer or filter........................................................................................... 170

HCC.J999 Fuel system drains.............................................................................................. 170

OIL SYSTEM.......................................................................................................................... 170

HCC.J1011 General ............................................................................................................. 170

HCC.J1013 Oil tanks............................................................................................................ 171

HCC.J1015 Oil tank tests..................................................................................................... 172

HCC.J1017 Oil lines and fittings ......................................................................................... 172

HCC.J1019 Oil strainer or filter........................................................................................... 172

HCC.J1021 Oil system drains.............................................................................................. 173

HCC.J1023 Oil radiators...................................................................................................... 173

HCC.J1025 Oil valves.......................................................................................................... 173

COOLING ............................................................................................................................... 173

HCC.J1041 General ............................................................................................................. 173

HCC.J1043 Cooling tests..................................................................................................... 174

HCC.J1045 Cooling test procedures.................................................................................... 174

LIQUID COOLING ................................................................................................................ 176
Document Number: 1008D0122

Revision: C

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HCC.J1061 Installation ........................................................................................................ 176

HCC.J1063 Coolant tank tests ............................................................................................. 177

INDUCTION SYSTEM .......................................................................................................... 177

HCC.J1091 Air intake .......................................................................................................... 177

HCC.J1093 Air intake system de-icing and anti-icing provisions....................................... 178

HCC.J1101 Carburetor air preheater design ........................................................................ 179

HCC.J1103 Induction system ducts..................................................................................... 179

HCC.J1105 Air intake system screens................................................................................. 179

HCC.J1107 Inter-coolers and after-coolers.......................................................................... 180

HCC.J1108 Induction system filters .................................................................................... 180

HCC.J1111 Turbine engine bleed-air system ...................................................................... 180

EXHAUST SYSTEM.............................................................................................................. 180

HCC.J1121 General ............................................................................................................. 180

HCC.J1123 Exhaust piping.................................................................................................. 181

HCC.J1125 Exhaust heat exchangers................................................................................... 181

APU CONTROLS AND ACCESSORIES.............................................................................. 181

HCC.J1141 APU controls: general ...................................................................................... 181

HCC.J1143 APU Engine controls........................................................................................ 182

HCC.J1145 Ignition switches............................................................................................... 182

HCC.J1147 Mixture controls ............................................................................................... 183

HCC.J1157 Carburetor air temperature controls.................................................................. 183

HCC.J1163 APU Powerplant accessories............................................................................ 183

HCC.J1165 Engine ignition systems.................................................................................... 184

APU POWERPLANT FIRE PROTECTION.......................................................................... 184

HCC.J1181 Designated fire zones: regions included........................................................... 184

HCC.J1182 Areas behind firewalls, and engine pod attaching structures containing 

flammable fluid lines............................................................................................................ 185

HCC.J1183 Flammable fluid-carrying components............................................................. 185

HCC.J1185 Flammable fluids.............................................................................................. 185

HCC.J1187 Drainage and ventilation of fire zones.............................................................. 186

HCC.J1188 Ventilation ........................................................................................................ 186

HCC.J1189 Shut-off means.................................................................................................. 186

HCC.J1191 Firewalls........................................................................................................... 187

HCC.J1192 Engine accessory compartment diaphragm...................................................... 188

HCC.J1193 APU Engine compartment................................................................................ 188

HCC.J1195 Fire extinguishing systems............................................................................... 188

HCC.J1197 Fire extinguishing agents.................................................................................. 188

HCC.J1199 Extinguishing agent containers ........................................................................ 189

HCC.J1201 Fire extinguishing system materials................................................................. 189

HCC.J1203 Fire detector system.......................................................................................... 189

HCC.J1207 Compliance....................................................................................................... 190

APPENDICES........................................................................................................................... 191

APPENDIX A Tables and data................................................................................................ 191

APPENDIX B Tearing strength test ....................................................................................... 199

APPENDIX C Definitions and abbreviations......................................................................... 200
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General Definitions and Acronyms......................................................................................... 200

Abbreviations and Symbols..................................................................................................... 205

List of Tables

Table 1 - Design maneuver conditions ....................................................................................... 191

Table 2 - Pilot Forces.................................................................................................................. 192

Table 3 - Takeoff and landing conditions................................................................................... 193

Table 4 – Mooring and handling conditions............................................................................... 194

Table 5 - General tolerances during flight testing ...................................................................... 194

Table 6 - Maximum pilot forces ................................................................................................. 195

Table 7 - Ultimate inertia forces in units of gravity.................................................................... 195

Table 8 – Noncritical castings..................................................................................................... 195

Table 9 – Motion and effect of cockpit controls......................................................................... 196

Table 10 – Minimum intensities in the horizontal plane position lights..................................... 196

Table 11 – Minimum intensities in any vertical plane position lights........................................ 196

Table 12 – Maximum intensities in overlapping beams............................................................. 197

Table 13 – Minimum effective intensities for anti-collision lights............................................. 197

Table 14 – Strength values for high pressure pneumatic systems .............................................. 198
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Hybrid Certification Criteria (HCC) for Transport Category Hybrid Airships 

Subpart A - General 

HCC.1 Applicability 

This Criteria is applicable to the Lockheed Martin model LMZ1M hybrid airship and constitutes 

the airworthiness part of the Certification Basis.
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Subpart B - Flight 

GENERAL 

HCC.21 Proof of compliance 

(a) Each requirement of these criteria must be met at each appropriate combination of total 

mass, static heaviness and lightness and center of gravity within the range of loading 

conditions that may occur during the operations for which certification is requested. This must 

be shown by tests upon an Airship of the type for which certification is requested, or by 

calculations based on, and equal in accuracy to the results of testing or a combination of each. 

(b) Systematic investigation is required of each probable combination of mass and center of 

gravity, if compliance cannot be reasonably inferred from combinations investigated. 

(c) The controllability, stability, trim, and stalling characteristics, where relevant, of the 

Airship must be shown at all airspeeds with various ballonet or gas cell levels. 

(d) The following general tolerances from specified values are allowed during flight testing: 

The manner and extent to which variations of other relevant data of the Airship are to be taken 

into account in establishing compliance with the performance requirement, and in scheduling 

performance data, must be established for the product. 

(e) If compliance with the flight characteristics requirements is dependent upon a stability 

augmentation system or upon any other automatic or power-operated system, compliance 

must be shown with HCC.672. 

(f) For take-off, landing and ground handling the wind and gust velocity must be measured at 

the height of hull axis when parked, or corrected for the height at which the wind velocity is 

measured. 

HCC.23 Load distribution limits 

(a) Ranges of mass, static heaviness and lightness and lift and corresponding centers of 

gravity and lift must be established, within which the Airship may be safely operated. 

(b) The load distribution limits may not exceed the: 

(1) selected limits; 

Item Tolerance

Mass +5%, -10%

Critical items affected 

by mass

+5%, -1%

Center of gravity ±7%

Airspeed ±3 knots or ±3% 

whichever is higher
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(2) limits at which the structure is proven; or: 

(3) limits at which compliance with each applicable flight requirement of this Subpart is 

shown. 

(c) The flight crew must have means to determine the static heaviness / lightness of the 

Airship at any time. 

HCC.25 Mass limits 

(a) Maximum mass: the maximum mass is the highest mass at which compliance with each 

applicable requirement of these criteria is shown. The maximum mass must be established so 

that it is: 

(1) not more than: 

(i) the highest mass selected for the product, 

(ii) the design maximum mass, which is the highest mass at which compliance with 

each applicable structural loading condition of these criteria is shown, or 

(iii)The highest mass at which compliance with each applicable flight requirement is 

shown;

(2) not less than that which can be achieved with the payload-car or keel loaded to its 

maximum design mass 

(b) Minimum mass: the minimum selected mass (the lowest mass at which compliance with 

each applicable requirement is shown) must be established so that it is not less than: 

(1) the lowest mass selected for the product; 

(2) the design minimum mass (the lowest mass at which compliance with each structural 

loading condition is shown); or 

(3) the lowest mass at which compliance with each applicable flight requirement is shown. 

HCC.27 Center of gravity limits 

The horizontal, vertical and lateral center of gravity limitations must be established for each 

practicably separable operating condition. 

HCC.29 Empty mass and corresponding center of gravity 

(a) The empty mass and corresponding center of gravity must be determined from the mass of 

all items, including the structure, and: 

(1) the mass of the deflated gas cells and envelope; 

(2) Fixed ballast; 

(3) Unusable fuel determined under HCC.959; and: 

(4) Full operating fluids, including 

(i) Oil; 
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(ii) Hydraulic fluid; 

(iii) other fluids required for normal operation of the Airship systems. 

(b) The condition of the Airship at the time of determining empty mass must be one that is 

well defined and repeatable. 

(c) A means of accounting for empty mass and center of gravity changes during the life of the 

Airship, other than by calculation only, must be established. 

HCC.31 Removable ballast 

Removable ballast as defined in Appendix C may be used in showing compliance with the flight 

requirements of this subpart, if: 

(a) the place for carrying ballast is properly designed and installed, and is marked under 

HCC.1557; 

(b) instructions are published in the Airship Flight Manual, approved manual material, or 

markings and placards, for the proper placement of the removable ballast under each loading 

condition for which removable ballast is necessary. 

(c) distribution of removable ballast in terms of inertia must be considered, beside basic mass 

and center of gravity effects, as this may be a significant factor on handling characteristics 

such as oscillatory behavior and/or stabilities. 

HCC.33 Propeller speed and pitch limits 

(a) General: The propeller speed and pitch must be limited to values that will assure safe 

operation under normal operating conditions. 

(b) Propellers not controllable in flight: for each propeller, the pitch of which cannot be 

controlled in flight, during take-off and initial climb at best rate of climb speed, the propeller 

must limit the engine rpm., at full throttle or at maximum allowable take-off manifold 

pressure, to a speed not greater than the maximum allowable take-off rpm.

(c) Controllable pitch propellers without constant speed controls: each propeller that can be 

controlled in flight, but that does not have constant speed controls, must have a means to limit 

the pitch range or an indication of the propeller pitch angle or thrust so that the lowest 

possible pitch allows compliance with subparagraph (b) of this paragraph. 

(d) The means used to limit the low pitch position of the propeller blades must be set so that 

the engine does not exceed 103% of the maximum allowable engine rpm or 99% of an 

approved maximum overspeed, whichever is greater, with: 

(1) the propeller blades at the low pitch limit and governor inoperative; 

(2) the Airship stationary under standard atmospheric conditions with no wind; and 

(3) the engines operating at the maximum take-off torque limit for turboprop enginepowered Airships. 

(e) controllable pitch propellers with constant speed controls: each controllable pitch propeller 

with constant speed controls must have: 
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(1) with the speed control in operation, a means at the speed control to limit the maximum 

engine speed to the maximum allowable takeoff rpm; 

(2) with the speed control inoperative, a means to limit the maximum engine speed to 

103% of the maximum allowable takeoff rpm with the propeller blades at the lowest 

possible pitch and with takeoff manifold pressure, the Airship stationary, and no wind. 

PERFORMANCE

HCC.45 General 

(a) Unless otherwise prescribed, the performance requirements of this subpart must be met for 

still air; and ambient atmospheric conditions defined for the product. 

(b) The performance data must correspond to the vectored, propulsive thrust available under 

the particular ambient atmospheric conditions, the particular flight condition, and the relative 

humidity specified in subparagraph (d) of this paragraph. 

(c) The available propulsive thrust must correspond to engine power or thrust, not exceeding 

the approved power or thrust, less: 

(1) installation losses; 

(2) the power or equivalent thrust absorbed by the accessories and services appropriate to 

the particular ambient atmospheric conditions and the particular flight condition. 

(d) The performance, also as affected by engine power or thrust, must be based on a relative 

humidity selected for the product or as a minimum of: 

(1) 80% at or below standard temperature; 

(2) 34% at and above standard temperature plus 50°F (28°C); 

(3) Between the two temperatures listed in subparagraphs (d)(1) and (d)(2) of this 

paragraph, the relative humidity must vary linearly. 

(e) The following also apply: 

(1) Unless otherwise prescribed, the applicant must select the takeoff, en route, approach, 

and landing configurations for the Airship; 

(2) The Airship configuration may vary with mass, static heaviness and lightness, altitude, 

and temperature, to the extent they are compatible with the operating procedures required 

by subparagraph (e)(3) of this paragraph; 

(3) Unless otherwise prescribed, in determining take-off performance, take-off flight path, 

take-off distance, and landing distance; changes in the Airship's configuration, speed, 

power, and thrust must be made in accordance with procedures established for the product 

for operation in service; 

(4) Procedures for the execution of missed approaches and balked landings associated with 

the conditions prescribed in HCC.65, 67 and 77 must be established; 

(5) The procedures established under subparagraphs (e)(3) and (e)(4) of this paragraph 

must: 
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(i) be such that they can be executed consistently by a crew of average skill, 

(ii) use methods or devices that are safe and reliable, 

(iii) include allowance for any reasonably expected time delays in the execution of the 

procedures.

(6) The performance data established shall be the minimum performance of an Airship or 

group of Airships being tested by an acceptable method in the specified conditions. 

(7) For the determination of takeoff performance: 

(i) the starting point shall be the point on the takeoff surface from which a stationary 

Airship commences the takeoff maneuver, and 

(ii) the decision point airspeed shall be the latest point at which, as a result of power 

unit failure, the pilot is assumed to decide to continue or discontinue a take-off. 

HCC.49 Performance at minimum operating speed 

(a) The hovering performance must be determined over the ranges of static heaviness, 

altitude, and temperature for which takeoff data are published in the Airship Flight Manual

with:

(1) Takeoff power;

(2) The ACLS extended; and

(3) At a height consistent with the procedure used in establishing the takeoff, climb out, 

and rejected takeoff paths.

(b) The steady rate of climb at the minimum operating speed must be determined over the 

ranges of static heaviness, altitude, and temperature for which certification is requested with:

(1) Takeoff power; and

(2) The ACLS extended.

HCC.51 Takeoff 

(a) The takeoff performance data and procedures for Airships, equipped with ACLS and 

requiring a horizontal takeoff when operating statically heavy, the distance*required to 

takeoff and clear a 50-ft obstacle must be determined and published in the Airship Flight 

Manual: 

(1) For each appropriate combination of total mass, static heaviness and the most 

unfavorable center of gravity within the range of loading conditions for which certification 

is requested, and for ambient atmospheric temperature and wind conditions within the 

operational limits selected for the product; 

(2) For the selected configuration for takeoff; 

(3) For the most unfavorable center of gravity position; 
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(4) With the engines and vectored thrusters (if so equipped) operated within approved 

operating limits. 

*The takeoff distance shall be measured from the tailpoint of the Airship to 50 feet above the 

takeoff surface. 

(b) For each takeoff technique published in the Airship Flight Manual, the horizontal distance 

from the starting point to the point at which 50 feet above the takeoff surface is attained shall 

be measured when taking off at maximum static heaviness:

(1) with all engines operating throughout, and 

(2) with all engines operating up to the decision point airspeed then with the critical engine 

inoperative from the decision point onward. 

In both cases the speed at the 50 foot height must be not less than the initial steady climb 

speed appropriate to the number of operating engines and to the static heaviness. 

(c) For each takeoff technique published in the Airship Flight Manual, the horizontal distance 

to accelerate from the starting point to the decision point with all engines operating then to 

come to a complete stop with the critical engine inoperative shall be established. 

(d) The established techniques for takeoff shall include the recommended pitch attitudes 

appropriate to the initial steady climb and the associated speeds appropriate to the number of 

operating engines and the static heaviness (or lightness). The initial climb speed shall be not 

less than: 

(1) the speed at which the climb performance minimum of HCC.65 and HCC.67 

appropriate to the number of engines can be met, and 

(2) 1.10 times the minimum speed at which the requirements of HCC.149 can be met with 

a transient heading change of no more than 20° and with the ability to subsequently regain 

and maintain the original heading. 

The all engines operating initial climb speed may not be less than the one engine inoperative 

steady initial climb speed.

(e) The minimum space required for takeoff shall be: 

(1) a circle of diameter not less than the length of the Airship plus whichever is the greater 

of: 

(i) 328 ft (100 m) plus the measured takeoff distance with all engines operating 

established in accordance with (b)(1), 

(ii) 1.33 times the measured takeoff distance with all engines operating established in 

accordance with (b)(1), 

(iii) 197 ft (60 m) plus the measured takeoff distance with one engine inoperative 

established in accordance with (b)(2), 
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(iv) 1.15 times the measured takeoff distance with one engine inoperative established in 

accordance with (b)(2) and, where the decision point is later than the point where the 

ship is released by the ground crew, 

(v) the accelerate-stop distance determined in accordance with (c), or 

(2) a rectangle of length equal to the diameter of the circle defined in (e)(1) and a width not 

less than the width of the Airship plus 656 ft (200 m). 

(f) Where the minimum space required for take-off, as published in the Airship Flight 

Manual, is a rectangle, in accordance with (e)(2), the maximum permitted wind component at 

right angles to the major axis of the rectangle must be published in the Airship Flight Manual. 

(g) Takeoffs made to determine the data required by this paragraph must not require 

exceptional piloting skill or favorable conditions. 

HCC.65 Climb: all engines operating 

(a) Each Airship, at maximum mass, static heaviness and at ambient atmospheric temperature 

within the operational limits established for the Airship and with the most unfavorable center 

of gravity for each configuration, and when the Airship is operated in accordance with the 

takeoff techniques established in accordance with HCC.51, must have a steady rate of climb 

at the airfield altitude of at least 400 ft/min (2.0 m/s) and a steady angle of climb of at least 

1:12 with: 

(1) thrust and lift controls in their normal position for climb; 

(2) the landing gear or device retracted, if applicable; and 

(3) not more than Maximum Takeoff Power and at the initial all-engines-operating climb 

speed of HCC.51(d). 

(b) It must be demonstrated that envelope and gas cell pressures remain within the maximum 

and minimum approved pressures during climbs and descents at rates of ascent and descent of 

at least 1200 ft/min (7 m/s). 

(c) For Airships in which the primary supply of air to the Ballonets is dependent upon engine 

power, the maximum Rate of Descent shall be established and published in the Airship Flight 

Manual both for the all-engines-operating condition and with the Critical Engine inoperative. 

The latter case may be demonstrated either with the Critical Engine inoperative or with the air 

supply from the Critical Engine shut-off. 

(d) Performance data must be determined for variations in mass, static heaviness, altitude and 

temperature at the most unfavorable center of gravity for which approval is requested. 

HCC.67 Climb: critical engine inoperative 

(a) Each Airship, with the most critical engine inoperative and with or without vectored 

thrust, at various combinations of mass, static heaviness and at ambient atmospheric 

temperature within the operational limits established for the Airship and with the most 

unfavorable center of gravity for each configuration, and when the Airship is operated in 

accordance with the takeoff techniques established in accordance with HCC.51, must have a 

steady rate of climb at the airfield altitude of at least 150 ft/min (0.76 m/s) with: 
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(1) thrust and lift controls in their normal position for climb; 

(2) the landing gear or device retracted, if applicable; and 

(3) the operating engines operating at not more than Maximum Takeoff Power and at the 

initial one-engine-inoperative climb speed of HCC.51(d). 

(b) Performance data must be determined for variations in mass, static heaviness, altitude and 

temperature at the most unfavorable center of gravity for which approval is requested. 

HCC.68 En-route flight path 

(a) For the en-route configuration, the flight paths prescribed in (b) and (c) of this paragraph 

must be determined at each mass, altitude, and ambient temperature, within the operating 

limits established for the Airship. The variation of mass along the flight path, accounting for 

the progressive consumption of fuel and oil by the operating engines, and also accounting for 

accumulation of water or snow onto the envelope of the Airship must be included in the 

computation. The flight path must be determined at the associated climb speed and 

recommended pitch attitude, with: 

(1) the most unfavorable center of gravity; 

(2) the most critical engine inoperative (except for the flight path prescribed in (d) of this 

paragraph; 

(3) the operating engines at the available maximum continuous power or thrust, and; 

(4) the means for controlling the engine cooling air supply in the position that provides 

adequate cooling in the hot day condition 

(b) The most critical engine inoperative net flight path data must be established; 

(c) Reserved

(d) The measured rate and gradient of climb with all engines operating must be established. 

(e) The maximum level flight speed shall be not less than VBmin (see HCC.311) in the 

following conditions: 

(1) Buoyancy. Maximum permitted Static Heaviness or Static Lightness, whichever affects 

speed more adversely. 

(2) Power. All engines operating at not more than Maximum Continuous Power. 

HCC.75 Landing 

(a) For Airships equipped with ACLS and capable of making horizontal landings the 

horizontal distance* necessary to land and come to a complete stop from clearing a point 50 ft 

(15 m) above the landing surface must be determined for each technique published in the 

Airship Flight Manual, with the Airship in the most critical configuration for landing. If any 

device is used that depends on the operation of any engine(s), and if the landing distance 

would be noticeably increased when a landing is made with the most critical engine 

inoperative, the landing distance must be determined with that engine inoperative unless the 

use of compensating means will result in a landing distance not more than that with all 

engines operating.
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*The distance shall be measured from the obstacle to the bow of the stopped Airship.

(b) For Airships which are capable of vertical landings, performance data must be established 

for each technique published in the Airship Flight Manual with the Airship in the most critical 

configuration for landing.

(c) Landing performance and data must be determined and published in the Airship Flight 

Manual: 

(1) for standard temperatures at each mass and static heaviness, altitude and wind condition 

within the operational limits established for the product; 

(2) for the selected configuration for landing; 

(3) for the most unfavorable center of gravity position; 

(4) with the engines operated within approved operating limits 

HCC.76 Engine failure 

The Airship must be capable of maintaining level flight and zero rate of descent following failure 

of the most critical engine. Ballast may be dropped or helium vented to achieve these conditions. 

Only disposable ballast may be dropped. 

HCC.77 Balked landing 

Each Airship must demonstrate the ability to transition to a balked landing climb from a descent 

and approach to landing in accordance with established procedures in the Airship Flight Manual, 

at maximum landing mass and static heaviness without excessive sink or requiring excessive 

pilot skill. The Airship configuration will include: 

(a) the Airship trimmed for descent and landing; 

(b) the ACLS extended; and 

(c) thrust and lift controls initially in the position normally used for landing. 

HCC.80 Loading/Unloading 

(a) For Airships intended to load and unload cargo or other ballast when the Airship is in 

flight, hovering, or on the ground, operating limits must be established with the Airship in the 

most critical configuration. 

(b) Loading/Unloading operating limits must be determined and published in the Airship 

Flight Manual: 

(1) for standard temperatures at each weight and static heaviness, altitude, and wind 

condition within the operational limits established for the product; 

(2) for the selected configuration for loading/ unloading; 

(3) for the most unfavorable center of gravity position; 

(4) with the engines operated within approved operating limits. 

(c) During any cargo exchange or reballasting operation the Airship must be capable of 

achieving a safe free flight condition within a time period short enough to recover from a 

potentially hazardous condition.
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FLIGHT CHARACTERISTICS 

HCC.141 General 

(a) The Airship must meet the requirements of HCC.143 through 261 at all approved 

operating altitudes and ambient atmospheric conditions without exceptional piloting skill, 

alertness, or strength. 

(b) In the course of establishing compliance with the requirements of HCC.143 through .261, 

a general qualitative assessment of the handling qualities shall be made. If this assessment 

reveals any unusual features not specifically covered by the Requirements then the handling 

qualities in this respect shall be satisfactory to the Administrator. 

(c) Although the requirements as detailed in HCC.143 through .261 are, in general, associated 

with no appreciable atmospheric turbulence, a qualitative check shall be made to ensure that 

there is no undue deterioration in the handling characteristics in turbulent air. 

CONTROLLABILITY AND MANEUVERABILITY

HCC.143 General 

(a) The Airship must be safely controllable and maneuverable during:

(1) Takeoff; 

(2) Climb; 

(3) Level flight; 

(4) Descent; 

(5) Landing; 

(6) Level flight with the most critical engine inoperative and remaining engines vectored in 

any allowable position. 

(7) in flight cargo exchange and reballasting operations and during passenger or cargo 

loading and unloading with the Airship on the ground.

Dynamic response due to modes of motion must be considered to ascertain that no abnormal 

modes of motion, flight attitudes and accelerations will occur on account of the maneuvers 

induced. 

(b) It must be shown that without engine power descent and landing under the conditions of 

HCC.561 can be made. 

(c) It must be possible to make a smooth transition from one flight condition to any other 

flight condition without exceptional piloting skill, alertness, or strength and without danger of 

exceeding the limit-load factor under any probable operating condition, including the sudden 

failure of any engine, and:

(1) for airships with three or more engines the sudden failure of the second critical engine 

when the airship is in the en-route, approach, or landing configuration and is trimmed with 

the critical engine inoperative. If the airship does not have the ability to maintain altitude,

the airship must be capable of maintaining a safe descent rate and control during landing 

per HCC.153; and: 
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(2) configuration changes, including use of deceleration devices. 

(d) If, during the testing required by subparagraph (c) of this paragraph, marginal conditions 

exist with regard to required pilot strength, the pilot forces may not exceed the limits 

prescribed in Table 6 of Appendix A. For the purpose of complying with prolonged control 

force limitations the Airship must be trimmed for buoyancy and pitch as close to neutral as 

possible. 

HCC.145 Longitudinal control 

With all engines operating at maximum continuous power, appropriate lift control settings, the 

Airship trimmed and without exceeding the pilot forces of Table 6 in Appendix A, it must be 

possible to produce a reasonably sudden: 

(a) nose-down pitch change out of a stabilized climb with 30° nose-up deck angle at the most 

critical airspeed.

(b) nose-up pitch change out of a stabilized descent with 30° nose-down deck angle at the 

most critical airspeed.

HCC.147 Directional control 

There must be enough rudder control to enter and recover any turns appropriate to the conditions 

for which certification is requested with pilot forces not exceeding the values given in Table 6 of 

the Appendix A. Additionally it must be demonstrated that directional control can be maintained 

with and against asymmetric engine thrust due to the failure of the most critical engine.

HCC.149 Minimum control speed 

(a) VMC is the calibrated airspeed at which, when the most critical engine is suddenly made 

inoperative, it is possible to maintain control of the Airship, with that engine still inoperative, 

and thereafter maintain straight flight at the same speed. 

The method used to simulate the most critical engine failure must represent the most critical 

mode of powerplant failure with respect to controllability expected in service. 

(b) For Airships equipped with ACLS and capable of making horizontal landings the 

requirements of sub-paragraph (a) must also be met for the landing configuration with: 

(1) Maximum available takeoff power initially on each engine; 

(2) The Airship trimmed for an approach with all engines operating at an approach gradient 

equal to the steepest used in the landing distance demonstration of HCC.75; 

(3) ACLS extended; and 

(4) All propeller controls throughout in the position recommended for approach with all 

engines operating.

(c) At VMC, the temporary control forces specified in Table 6 of Appendix A must not be 

exceeded and it must not be necessary to reduce power of the operative engine. During the 

maneuver the Airship must not assume any dangerous attitude and it must be possible to 

prevent a heading change of more than 20°. 
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HCC.150 Minimum aerodynamic control speed 

The minimum aerodynamic control speed VAM is the minimum airspeed at which it is possible to 

maintain directional and longitudinal control and zero rate of descent of the Airship with 

aerodynamic means for various combinations of mass and static heaviness during takeoff, flight 

and landing. 

HCC.153 Control during landings 

(a) Sufficient pitch and yaw control authority must exist under all appropriate approach and 

landing conditions defined in the Airship Flight Manual to permit the pilot to achieve the 

desired attitude and position. The means, technique and limits for such control must be 

published in the Airship Flight Manual. 

(b) It shall be possible to make a landing without assistance from ground personnel in the 

maximum surface wind speed established in accordance with HCC.237. This requirement 

shall be met with all engines operating and with the Critical Engine inoperative. Satisfactory 

techniques for such a landing, which shall include procedures for securing the Airship to the 

ground, shall be determined and published in the Airship Flight Manual. 

(c) A technique shall be determined and published in the Airship Flight Manual for making an 

emergency landing with all engines inoperative in wind speeds up to the permitted maximum 

for operation. The technique shall make reference to the emergency evacuation technique as 

established in accordance with HCC.803 and shall include procedures for securing the Airship 

on the ground. If the use of a grapnel, or other device for bringing the Airship to rest, is 

prescribed, procedures for its deployment shall be given. 

TRIM 

HCC.161 Trim 

It shall be possible to trim the Airship by means of static or aerodynamic trim, in all conditions 

of loading, configuration, speed and power, to ensure that the pilot will not be unduly fatigued or 

distracted by actions necessary for the safe handling of the Airship. This applies both in normal 

operation and, if applicable, in the conditions associated with the failure of one engine, or with 

any likely single failure or malfunction of the Ballonet air supply system. 

STABILITY 

HCC.171 General 

It shall be demonstrated that the Airship is sufficiently stable in both pitch and yaw axes in 

steady unaccelerated flight during climb, descent, and level flight when trimmed at the 

appropriate operating speeds and with consistent use of auxiliary thrust and lift controls to ensure 

that the crew will not be unduly fatigued and distracted from their normal duties. 

HCC.181 Dynamic stability 

Any oscillation within the operating envelope of the Airship must be controllable with normal 

use of the primary flight controls without requiring exceptional pilot skills. 
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MISCELLANEOUS FLIGHT REQUIREMENTS 

HCC.201 Loss of aerodynamic lift demonstration 

Loss of aerodynamic lift characteristics, where relevant, shall be investigated in straight flight 

and turns; and with the ACLS and deceleration devices in any likely combination of positions 

approved for operation.

HCC.203 Loss of aerodynamic lift characteristics 

It must be possible to produce and to correct pitch and yaw by unreversed use of the controls, up 

to the time the Airship is stalled. No abnormal pitching may occur. The longitudinal control 

force must be positive up to and throughout the loss of aerodynamic lift. In addition, it must be 

possible to prevent stalling promptly and to recover from a stall by normal use of the controls. 

HCC.207 Loss of aerodynamic lift warning 

A loss of aerodynamic lift warning must be installed: 

(a) if the Airship can be stalled and then requires pilot action to recover; and, 

(b) the loss of aerodynamic lift of the Airship cannot be detected by the inherent aerodynamic 

qualities of the Airship. 

(c) The warning shall be furnished by a device that will give clearly distinguishable 

indications under expected conditions of flight. However, a visual stall warning device that 

requires the attention of the flight crew within the cockpit is not acceptable by itself. If a 

warning device is used, it shall provide a warning in each of the airship configurations 

prescribed in paragraph HCC.201. The stall warning for flight in icing conditions shall be 

provided by the same means as the stall warning for flight in non-icing conditions. In 

addition, a stall warning system, if required, shall provide an appropriate warning that is 

clearly audible to the flight crew under all foreseeable operating conditions.

HCC.231 Operations on Water

(a) A hybrid airship may not have dangerous or uncontrollable porpoising characteristics at 

any normal operating speed on the water.

(b) Hybrid airships must demonstrate satisfactory directional stability and control for water 

operations up to the maximum wind velocity specified in HCC.237.

(c) A wave height, demonstrated to be safe for operation, and any necessary water handling 

procedures for hybrid airships must be established.

(d) Spray may not dangerously obscure the vision of the pilots or damage the propellers or 

other parts of a hybrid airship at any time during taxiing, takeoff, and landing.

HCC.237 Wind velocities 

A maximum surface wind speed in which the Airship is allowed to operate shall be established 

and published in the Airship Flight Manual and in the Ground Handling Manual. This speed 

shall not be greater than the lesser of: 
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(a) 75% of the maximum still air speed of which the Airship is capable with the critical engine 

inoperative and the remaining engines operating at not more than maximum continuous 

power, or, 

(b) The maximum surface winds in which the Airship may be serviced by the ground crew. 

HCC.251 Vibration and buffeting 

(a) Each part of the Airship must be free from excessive vibration under any appropriate 

speed and power condition up to VCD as defined in HCC.311(c). In addition, buffeting must 

not occur in any normal flight condition severe enough to interfere with the control of the 

Airship, cause excessive fatigue to the crew, or result in loading beyond the limit load. 

(b) The requirements of (a) shall be met when the Airship is flown with normal use of the 

controls (including deliberate small, sharp inputs) and in all permitted conditions of 

buoyancy. 

HCC.253 Envelope pressure and distortion 

It must be shown that envelope or hull distortion and/or deflection will not interfere with flight 

path control throughout the range of speed, power and envelope pressure, if applicable, to be 

used in normal flight. For non-rigid Airships the following apply: 

(a) A means must be provided for the pilot to determine and control the envelope pressure 

within the design pressure range if applicable. 

(b) Improper use of the procedure and the controls necessary to comply with paragraph (a) 

must not damage the envelope or the structure attached to it. 

HCC.255 Ground handling characteristics 

(a) Satisfactory ground handling procedures must be developed assuming the specified 

minimum flight and ground crew, all anticipated Airship mass, buoyancy, failure and the 

wind conditions specified in HCC.237. 

(b) Mooring procedures must be developed. 

(c) Towing with mechanical means such as tractors and/or winches must strictly avoid line 

snapping or whipping by using appropriate means of pre-tensioning and controlled yield in 

case of suddenly incurred forces. 

(d) Ground handling equipment must be able to counteract ground gust conditions and wind 

shifts safely. 

(e) The Ground Handling Manual shall define the wind conditions addressed in (d) 

HCC.261 Flight in rough air 

(a) Procedures and performance information of the Airship at various levels of turbulence 

must be established for combinations of mass and static heaviness and be published in the 

Airship Flight Manual. 

(b) The lifting gas pressure must remain within its limits during flight in rough air. 
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Subpart C - Structure 

GENERAL 

HCC.301 Loads 

(a) Strength requirements are specified in terms of limit loads (the maximum loads expected 

in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). Unless 

otherwise provided, prescribed loads are limit loads. 

(b) Unless otherwise provided, the lifting gas-, air and ground loads must be placed in 

equilibrium with inertia forces and moments, considering each item of mass in the Airship, 

and, where appropriate, taking into account the effects of virtual inertia of the Airship (see 

definition of virtual inertia in Appendix C). Methods used to determine load intensities and 

distribution must be validated by flight load measurements unless the methods used for 

determining those loading conditions are shown to be conservatively approximate to or to 

closely represent actual conditions.

(c) Compliance with the structural requirements must be shown at critical combination of 

static and aerodynamic (where significant) lift and mass, from the design minimum to the 

design maximum and the most adverse combination of center of static and aerodynamic 

(where significant) lift and center of gravity position within the range for which certification 

is sought. 

(d) An enhancement factor of 1.33 must be used to establish limit loads where aerodynamic 

loads or load distributions are not reliably predictable, for example, empennages. 

(e) If deflections under load would significantly change the distribution of external or internal 

loads, this redistribution must be taken into account. 

(f) Loads and deflections as a function of static and aerodynamic (where significant) lift and 

mass distribution throughout the Airship's structure shall be considered. Procedures and 

placarding shall be used when necessary to prevent static and aerodynamic (where significant) 

lift and load distributions which would cause deflections and stresses above the maxima 

allowed. 

HCC.303 Factors of safety 

Unless otherwise specified, a factor of safety (FS) of 1.5 must be used. FS ULT=1.5*LIM.

HCC.305 Strength and deformation 

(a) The structure must be able to support limit loads without detrimental permanent 

deformation. At any load up to limit loads, the deformation must not interfere with safe 

operation. 

(b) The structure must be able to support ultimate loads without failure for at least 3 seconds. 

However, when proof of strength is shown by dynamic tests simulating actual load conditions, 

the 3 second limit does not apply. 

HCC.307 Proof of structure 

(a) Compliance with the strength and deformation requirements must be shown for each 

critical load condition. Structural analysis may be used only if the structure conforms to those 
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for which experience has shown this method to be reliable. In other cases, substantiating load 

tests must be made. Where substantiating load tests are made these must cover loads up to 

ultimate load, unless it is agreed with the Administrator that in the circumstances of the case, 

equivalent substantiation can be obtained from tests to agreed lower levels. Dynamic tests, 

including structural flight tests, are acceptable if the design load conditions have been 

simulated 

(b) Certain parts of the structure must be tested as specified in Subpart D of this HCC. 

HCC.309 Design mass 

The mass of the Airship is its mass with the envelope deflated plus the mass of the gas used to 

inflate the envelope. (See list of masses in App. C.). 

(a) Maximum design masses: the maximum masses at which compliance is shown with each 

applicable structural and flight requirement are defined below: 

(1) Maximum design equilibrium mass W0; 

(2) Maximum static heaviness Wsh (the amount by which the mass of an Airship exceeds 

the displacement buoyancy); 

(3) Maximum landing mass Wl; 

(4) Maximum takeoff mass Wt = W0 + Wtoh; 

(5) Maximum takeoff static heaviness Wtoh, (the amount by which the weight of the 

Airship exceeds the displacement buoyancy during takeoff); 

(b) Minimum design masses: the minimum masses at which compliance is shown with each 

applicable requirement are defined below: 

(1) Minimum design equilibrium mass Wm; 

(2) Maximum static lightness Wsl (The amount by which the mass of an Airship is less 

than the displacement buoyancy); 

(c) Static lift is the difference between the weight of air displaced by the Airship and the 

weight of the lifting gas. 

HCC.311 Design airspeeds 

The selected design airspeeds are equivalent airspeeds (EAS) except as provided in specific 

requirements. 

(a) Design maximum level flight airspeed VH is the maximum speed obtainable in level flight 

with all engines operating at maximum continuous power and the Airship loaded to 

equilibrium buoyancy or to loading which will produce minimum drag, whichever is greater. 

(b) Design airspeed for maximum gust intensity VB shall not be less than 35 knots or 0.65 VH, 

whichever is higher. 

(c) Design climb/dive airspeed VCD may not be less than the greater of: 

(1) VH; or the 
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(2) maximum airspeed obtainable in a climb with all (forward thrust) engines at maximum 

take-off power and the Airship in the minimum drag configuration and with maximum 

static lightness, or the

(3) maximum airspeed obtainable in a dive with all engines at maximum continuous power 

and the Airship in the minimum drag configuration and with maximum static heaviness.

(d) Design maneuvering speed VA: Speed at which, with full displacement of control (surface 

or engine), you will not exceed LIM load factor on airship.

(e) Design wind speed VWG is the maximum wind speed expected to occur during takeoff, 

landing, ground handling and grip mode. It is selected for the product but may not be less than 

10 knots. 

(f) Design wind speed VWT is the maximum wind speed to be expected with the Airship in 

grip mode during freight loading and unloading and passenger boarding and unboarding. 

(g) Design wind speed VWM, for airship in grip mode and/or secured by mooring, should meet 

the expected values but may not be less than specified in Table 4 of Appendix A.

FLIGHT LOADS 

HCC.321 General 

Compliance with the flight load requirements of this Subpart must be shown: 

(a) at each lift from the minimum design lift to the maximum design lift (static lift, 

aerodynamic lift, vectored thrust); 

(b) at each mass from the minimum design mass to the maximum design mass, also taking 

into account static heaviness as well as lightness; 

(c) at each critical altitude within the range in which the Airship may be selected to operate; 

(d) at each critical temperature at which the Airship is selected to be operated; 

(e) for each required lift, mass, altitude and temperature, at any practicable distribution of 

disposable load within the operating limitations specified in HCC.1583 through 1589; 

(f) when determining the loads, the influence of precipitation consistent with the operating 

condition sought must be accounted for. 

HCC.333 Design maneuvering loads

(a) The Airship, including control surfaces and thrusters, is considered to be subjected to the 

loads resulting from the maneuvering conditions listed in Table 1 of Appendix A. Steady state 

and transient effects during checked and unchecked maneuver must be taken into account.

(b) Consideration of the maneuvering conditions must include the investigation of both the 

separate and the combined effects of the rudder and elevator control surfaces plus other 

related means of control as (but not limited to) lift- and mass-shift.

(c) Consideration of the maneuvering conditions must include the investigation of the effect 

of the vectored thrust.
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HCC.341 Gust and turbulence loads 

The loads resulting from gusts and turbulence may either be determined by an analytical 

simulation of flight through random turbulence and discrete gusts with the results compared with 

values derived from the equation in subparagraph (c); or by applying subparagraph (a) and (b). 

(a) The Airship is assumed to be subjected to the loads resulting from encounters with the 

following atmospheric gusts in level flight: 

(1) discrete gust of Um=25 ft/s (7.6 m/s) while flying at speed v=VH (ft/s); 

(2) discrete gust of Um=35 ft/s (10.6 m/s) while flying at speed v=VB (ft/s).

Gust shapes and intensities u are defined as follows: 

u = Um/2 [1 - cos(X/H)] {ft/sec}

where: 

Um gust velocity specified above (ft/s), 

X penetration distance (ft), 0 < X < 2 H,

H gust gradient length (ft), L/4 < H < 800 ft (244 m), (a sufficient number of gust gradient length 

must be investigated to find the critical response of the Airship)

L length of the Airship (ft).

The dynamic response of the Airship to the design gusts as well as the steady state loads must be 

taken into account.

(b) The gusts are applied in any direction, including parallel to the Airship longitudinal axis, 

with the control surfaces in both the neutral position and the maximum effective angles 

required to counteract the gust. 

(c) In the absence of a more rational analysis, the maximum aerodynamic bending moment M 

(lb×ft), applied to the envelope, must be computed as follows: 

M = 0.058 V (L/2)1/4 [1 + (f-4) (0.5624 L0.02 -0.5)] qUm/v {ft-lb}

where: 

f envelope ratio, f= (equivalent) envelope ratio = L/Dequivalent. Deq = sqrt(Volume/L),

Um gust velocity from subparagraph (a) of this paragraph (ft/s), 

q dynamic pressure (lb/ft2) at the velocity v (ft/s) under consideration, q=rv2/2, 

L length of the Airship (ft), 

D Dequivalent. Deq = sqrt(Volume/L), 

r density of air (slugs/ft3), 

v Airship equivalent speed (ft/s) from subparagraph (a) of this paragraph, 

V total envelope volume (ft3). 

(d) The empennage is assumed to be subjected to the discrete gusts defined in subparagraph 

(a) applied under the following conditions. 

(1) The Airship is in straight and level flight; 

(2) The gust is applied at 90° to either side of tail surfaces; 

(3) Control surfaces must be considered to be in both the neutral position and at the 

maximum effective angles required to counteract the gust; 

(4) The effective angle of attack is assumed to be: α = 1.25 tan-1(Um/1.689 V)
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(5) Control surface loads plus stern aerodynamic forces in the hull induced by the 

empennage must be placed in equilibrium with opposing inertia forces and/or mooring 

point forces in a rational or conservative manner with the Airship at its design mass.

HCC.361 Engine and propeller and APU torque 

(a) Each engine mount and its supporting structure must be designed for the effects of: 

(1) A limit engine torque corresponding to maximum power and propeller speed acting 

simultaneously with 75% of the limit loads from the design maneuver conditions of 

HCC.333, or from the design gust conditions of HCC.341 and the landing impact loads of 

HCC.473(b); 

(2) A limit engine torque corresponding to the maximum continuous power and propeller 

speed acting simultaneously with the limit loads from the design maneuver conditions of 

HCC.333, or the limit loads from the design gust conditions of HCC.341 and the landing 

impact loads of HCC.473(b); 

(3) For turbopropeller installations: in addition to the conditions specified in subparagraphs 

(a)(1) and (a)(2) of this paragraph, a limit engine torque corresponding to maximum power 

and propeller speed, multiplied by a factor accounting for propeller control system 

malfunction, including quick feathering, acting simultaneously with 1 g level flight loads. 

In the absence of a rational analysis, a factor of 1.6 must be used.

(b) For turbopropeller installations, the engine mounts and supporting structure must be 

designed to withstand each of the following.

(1) A limit engine torque load imposed by sudden engine stoppage due to malfunction or 

structural failure (such as compressor jamming); 

(2) A limit engine torque load imposed by the maximum acceleration of the engine. 

(c) The limit engine torque, to be considered under subparagraph (a) of this paragraph, must 

be obtained by multiplying the mean torque by a factor of: 

(1) 1.25 for turbopropeller installations, unless power transients can cause a higher limit 

torque;

(2) and: 

(i) For four stroke engines with equal intervals between power strokes: 

(A) 1.33 for engines with five or more cylinders; 2, 3, 4 or 8 for engines with 4, 3, 2 

or 1 cylinders, respectively

(ii) For two stroke engines with equal intervals between power strokes: 

(A) 1.33 for engines with five or more cylinders;

(B) 1.5, 2.25, 3 or 6 for engines with 4, 3, 2 or 1 cylinders, respectively
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(iii) For discrete firing engines of configurations other than represented by (i) and (ii) 

above, the Authority must be consulted. 

(d) For diesel engine installations, the engine mounts and supporting structure must be 

designed to withstand the following:

(1) A limit engine torque load imposed by sudden engine stoppage due to malfunction or 

structural failure.

(i) The effects of sudden engine stoppage may alternatively be mitigated to an 

acceptable level by utilization of isolators, dampers clutches, and similar provisions, so 

unacceptable load levels are not imposed on the previously certificated structure.

(2) The limit engine torque to be considered under HCC.361(a) must be obtained by 

multiplying the mean torque by a factor of four for diesel cycle engines.

(i) If a factor of less than four is used, it must be shown that the limit torque imposed on 

the engine mount is consistent with the provisions of HCC.361(c). In other words, it 

must be shown that the use of the factors listed in HCC.361(c)(3) will result in limit 

torques on the mount that are equivalent to or less than those imposed by a conventional 

gasoline reciprocating engine.

(e) When the airflow through the propeller is not symmetrical, due to Airship yawing and 

pitching, engine vectoring or interaction from other thruster flow fields, the additional forces 

must be considered. 

HCC.363 Side load on engine and APU mounts 

(a) Each propulsive engine and auxiliary power unit mount and its supporting structure must 

be designed, in combination with maximum continuous forward or reverse thrust, for a limit 

load factor in a lateral direction, for the side load on the engine mount, at least equal to the 

maximum load factor in the yawing or gust condition but not less than

(1) 1.33; or: 

(2) One-third of the limit vertical load factor for design maneuver conditions specified in 

HCC.333. 

(b) The side load prescribed in subparagraph (a) of this paragraph may be assumed to be 

independent of other flight conditions. 

HCC.367 Unsymmetrical loads due to engine failure 

For turbopropeller powered Airships, the engine mount and support structure must be designed 

for the loads resulting from the failure of any one engine in combination with a single 

malfunction of the propeller drag limiting system. The following conditions apply.

(a) The loads resulting from power failure because of fuel flow interruption are considered to 

be limit loads. 

(b) The loads resulting from the disconnection of the engine compressor from the turbine or 

from loss of the turbine blades are considered to be ultimate loads. 
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HCC.371 Gyroscopic loads 

Each engine mount and its supporting structure must be designed for the gyroscopic loads 

resulting from pitch, yaw or roll rates induced from the maneuver or gust loads whichever is 

higher, acting in combination with the maximum rate of angular change in vectored thrust with 

the engines at maximum continuous rpm. 

CONTROL SURFACE AND SYSTEM LOADS 

HCC.391 Control surface loads: general 

(a) Control surfaces must be designed for the control surface loads resulting from the 

conditions described in HCC.333 and 341. 

(b) In the flight loading conditions, the airloads on movable surfaces and the corresponding 

deflections need not exceed those that would result in flight from the application of any pilot 

force within the ranges specified in HCC.397(b). However, these pilot forces may not be less 

than the actual maximum pilot forces determined when complying with HCC.143(c). In 

applying this requirement, the effects of control system boost and servo-mechanisms, and the 

effects of control surface inertia moments must be considered. The automatic pilot effort or 

any powered control system effort must be used for design if it alone can produce higher

control surface loads than the human pilot.

(c) Loads due to the accumulation of snow and ice to show compliance with HCC.505 have to 

be taken into account. A snow density of 31 lb/ft3(500 kg/m3) should be used to determine 

the loads. The maximum icing conditions that operation is requested for should be utilized to 

establish the ice loads.

HCC.395 Control system 

(a) Each flight control system and its supporting structure must be designed for limit loads 

corresponding to at least 1.25 of the computed hinge moments of the movable control surface 

in the conditions prescribed in HCC.333 and 341. However, these loads except the loads 

resulting from ground gusts need not exceed the higher of the loads that can be produced by 

the pilot, by the autopilot or any powered control system. 

(b) The system must be designed for the maximum effort of the pilot or autopilot, whichever 

is higher. In addition, the system should be designed for the case that the pilot and the 

autopilot act in opposition. Pilot forces used for design need not exceed the maximum forces 

prescribed in HCC.397(b). 

(c) The design must, in any case, provide a rugged system for service use. Compliance with 

this paragraph may be shown by designing for loads resulting from application of the 

minimum forces prescribed in HCC.397 (b).

HCC.397 Control system loads 

(a) Pilot forces used for design are assumed to act at the appropriate control grips or pads as 

they would in flight, and to be reacted at the attachments of the control system to the control

surface horns. 

(b) The pilot forces and torques to be applied are presented in Table 2 of the Appendix A. 
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HCC.399 Dual control system 

(a) Each dual control system must be designed for the pilots operating in opposition, using 

individual pilot forces not less than: 

(1) 0.75 times those obtained under HCC.391; or 

(2) The minimum forces specified in HCC.397(b). 

(b) The control system must be designed for pilot forces applied in the same direction, using 

individual pilot forces not less than 0.75 times those obtained under HCC.391.

HCC.405 Secondary control system 

Secondary controls, such manually operated air or lifting gas valves as well as freight loading 

system controls, must be designed for the maximum forces that a pilot or crew member is likely 

to apply to those controls. The required design forces for one-hand operation of secondary 

controls are as listed in Table 2 (c) of Appendix A. If two hands are needed the forces must be 

increased to 150%. The forces must be multiplied by the number of the people necessary for the 

operation, if applicable. If the actual forces for the operation of secondary controls are lower, 

they may be reduced, but not to be less than 200% of the actual forces.

HCC.407 Trim tabs effects 

The effects of trim tabs on the control surface design conditions must be accounted for. 

Where the surface loads are limited by maximum pilot effort the tabs are considered to be 

deflected in the direction that would assist the pilot. 

HCC.409 Tabs 

Control surface tabs must be designed for the most severe combination of airspeed and tab 

deflection likely to be obtained within the flight envelope for any useable combination of center 

of gravity position, heaviness or lightness.

HCC.411 Supplementary conditions for control surfaces 

For Airships with control surfaces having appreciable angles with respect to the horizontal and 

vertical axes or having inter surface supports, the surfaces and supporting structure must be 

designed for the combined surface loads prescribed for the separate systems. 

HCC.415 Tail-to-wind loads 

(a) The control system from the control surfaces to the stops, or when installed, the gust locks 

must be designed for limit loads corresponding to hinge moments calculated from the 

expression: 

MR = k⋅lR⋅SR⋅q [Nm] 

where: 

MR limit hinge moment [Nm], 

lR mean chord of control surface aft of the hinge line [m], 

SR area of the control surface aft of the hinge line [m2], 

q dynamic pressure corresponding to an air speed of 42.7 ft/s (13 m/s),

k limit hinge moment factor due to ground gust 1.40. 
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(b) In the absence of a more rational analysis, the load distribution on the movable control 

surface must be computed as varying linearly from zero at the hinge to a maximum value at 

the trailing edge. 

(c) The Airship structure shall be designed to withstand the limit loads resulting from a 25 

knot wind from dead astern or from any angle within a cone of 20° apex angle with its axis 

parallel to the longitudinal axis of the Airship while the Airship is parked. 

GROUND LOADS 

HCC.471 General 

The limit ground loads in this Subpart are considered to be external loads that act upon the 

ACLS and supporting structure. In each specified ground load condition, the external loads must 

be placed in equilibrium with the linear and angular inertia forces in a rational and conservative 

manner. 

HCC.473 Ground load conditions and assumptions 

(a) The ground load requirements of this subpart must be complied with for the following 

take-off and landing conditions:

(1) During a level take-off where the vehicle mass is Wt and the vertical ACLS load is 

1.5Wsh. Wt is the maximum takeoff mass and Wsh is the maximum design static heaviness.

(2) During a level landing with the ACLS in hover mode where the vehicle mass is Wl and 

the vertical ACLS load is the greater of nWl or 1.5Wsh. Wl is the maximum landing mass 

and n is the limit vertical inertia load factor at the C.G. of the airship selected under 

HCC.473(b).

(3) During a level landing with the ACLS in grip mode where the vehicle mass is Wl, the 

vehicle ground speed is at the grip mode landing limit in any direction, and the worst case 

vertical and horizontal ACLS loads are accounting for plenum suction, friction, and vehicle 

inertia.

(b) The selected limit vertical inertia load factor at the center of gravity of the Airship for the 

landing load conditions prescribed in this subpart may not be less than that which would be 

obtained when landing with an ACLS and the airship in heavy taxi/landing mode, at the 

maximum descent velocity expected to occur in service but may not be less than 3 ft/sec 

(0.914 m/sec). Proper consideration may be given to the distribution of the landing energy 

on the envelope and/or the surrounding structure. No allowance shall be made for dynamic lift 

throughout the landing impact. The limit vertical inertia load factor n represents the ratio of 

the externally applied vertical forces to the mass of the Airship. 

(c) Energy absorption tests (to determine the limit load factor n corresponding to the required 

limit descent velocities) must be made under HCC.723(a). 

(d) Except for Airships for which the structural flexibility effects are negligible, the effect of 

dynamic response of the structure must be covered by an analysis for the complete flight 

structure. The method of analysis must take into account at least the following elements: 

(1) the structural flexibility including the ACLS and supporting structure;

(2) the aerodynamic conditions assumed to be constant, and; 
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(3) an analytical model of the ACLS dynamic characteristics substantiated by an 

appropriate subscale test. 

HCC.479 ACLS loading condition 

The ACLS and supporting structure are considered to be subjected to the loads resulting from the 

takeoff and landing conditions as detailed in HCC.473(a). In determining the ground loads at the 

ACLS and affected support structure, the following apply:

(a) When investigating landing conditions, the drag components due to the ACLS must be 

properly combined with the corresponding instantaneous vertical ground reactions assuming 

an appropriate sliding coefficient of friction. The contact speed must be appropriate to landing 

the Airship at the maximum selected forward landing speed. 

(b) If the ACLS allows for landing in a sideslip condition, the ACLS and supporting structure 

must be designed to withstand the loads from a sideslip angle acting in the critical direction 

with respect to the ACLS and supporting structure.

(c) Auxiliary landing gear and/or supporting structure (e.g. wheels mounted on tail fin or 

cargo bay) must be designed to withstand the loads resulting from expected service. 

HCC.481 Mooring conditions 

The limit loads specified in this paragraph are considered to be external loads that act upon the 

Airship structure and mooring lines. The Airship must be designed for all loads arising from 

mooring under the conditions of Appendix A, Table 4 (Symmetrical and Unsymmetrical 

Mooring), and, separately, the loads arising on the moored Airship when operating one engine at 

maximum power. For these conditions, the Airship is considered in the landing configuration. In 

addition the following has to be shown:

(a) Reserved

(b) If tether points on the ground are used all values necessary for their design must be listed 

in the Ground Handling or Operating Manual. All static and dynamic loads must be 

determined considering the wind conditions to be expected during mooring. These values 

must be published in the Airship Flight Manual. The determination by analytical means is 

only acceptable if a procedure is used warranting reliable results. Otherwise appropriate 

ground tests have to be performed. Loads provided to the Airship by other ground support 

equipment, such as a tail down retaining ring, lateral guidance equipment or maintenance 

platforms need to be considered; 

(c) Reserved

(d) The investigation of service conditions must include validated field weather conditions 

while the Airship is moored during various gust and ambient conditions.

(e) Limit loads must be established for load exchange phase of flight when cargo, fuel and 

ballast are exchanged with the Airship in a hovering mode wherein its position is or is not 

maintained by vectored thrust and/or tethering to the ground. 
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OTHER LOADS 

HCC.505 Precipitation conditions 

(a) The design shall be such that the stability and control of the Airship is unlikely to be 

critically affected by such ice accretion as may occur during flight in anticipated operating 

conditions. 

(b) It must be shown by analysis that snow layers and partially sliding snow areas do not 

result in structural damage and/or uncontrollable conditions during flight. 

(c) Fine snow crystals penetrating into the Airship through crevices and openings must not 

accumulate to an extent that renders mechanisms or other parts of the Airship inoperative. 

(d) The limit load of precipitated snow on the parked Airship's surface must be established. A 

snow density of 31 lb/ft3should be used in determining the load limit.

HCC.507 Jacking loads 

The Airship must be designed for loads developed when supported by jacks or suspended from 

the hangar ceiling. Jacking points for the cars or the keel and attachment points for hangar 

ceiling suspension must be identified. The maximum mass and configuration of the Airship 

structure that can be supported in this manner must be determined. Appropriate load factors must 

be applied in the design and substantiated. 

HCC.509 Servicing access loads 

(a) Parts of the structure that may be used for supporting personnel during the rigging 

procedure, loading/unloading, boarding/unboarding, inspection, maintenance or repair on the 

ground must have the limit load multiplied by a load factor of 1.35 in addition to the factor of 

safety.

(b) If the parts mentioned under (a) must support personnel for servicing access in flight the in

flight n-factors must be applied. 

EMERGENCY LANDING CONDITIONS 

HCC.561 General 

(a) The Airship, including its propulsion system, although it may be damaged in emergency 

landing conditions, must be designed as prescribed in this paragraph to protect each occupant 

under those conditions. 

(b) The structure must be designed to give each occupant every reasonable chance of escaping 

serious injury in a minor crash landing when: 

(1) proper use is made of seat belts provided for in the design for designated flight seats; 

(2) the occupant experiences the ultimate inertia forces shown in Table 7 of the Appendix 

A. 
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(3) A demonstration is completed showing the airship has a powered off descent rate less 

than or equal to 20 feet/second (1,200 ft/min) at no more than 25 knots forward velocity 

true airspeed;

(4) An analysis is completed for the airship design showing the descent rate in (3) with a 

1.5 factor of safety cannot exceed the ultimate inertia forces shown in Table 7 of Appendix 

A for a minor crash landing.

(c) The supporting structure must be designed to restrain, under loads up to those specified in 

subparagraph (b)(2) of this paragraph, each item of mass that could injure an occupant if it 

came loose in a minor crash landing. 

(d) In addition to c) the following apply: 

(1) Engines and propellers which would pass through any part of the normal passenger or 

crew accommodation if they moved forward within a cone of 30° apex angle, the apex of 

the cone being at the engine c.g. and its axis parallel to the longitudinal axis of the Airship, 

shall have attachments sufficient to withstand an ultimate acceleration of 6 g forwards as 

defined by the cone. 

(2) In addition, each engine and propeller shall be secured in a manner which will ensure 

that it will not pass through such accommodation when subject to any combination of 

forward acceleration up to 6 g and downward acceleration up to 6 g. 

FATIGUE EVALUATION 

HCC.571 General 

The structure must be designed, as far as practical, to avoid points of stress concentration where 

cyclic stresses above the fatigue limit are likely to occur in normal service. An evaluation of the 

strength, detail design, and fabrication must show that catastrophic failure due to fatigue, 

corrosion, or accidental damage, will be avoided throughout the operational life of the Airship. 

This evaluation must be conducted in accordance with the provisions of subparagraphs (a)(1), (b) 

and (d) of HCC.573, except as specified in subparagraph (a)(2) of this HCC.573, for each part of 

the structure which could contribute to a catastrophic failure (such as, but not limited to, 

envelope or structure, the failure of which could affect buoyancy and dynamic lift, structure 

supporting aerodynamic form of envelope, empennage, control surfaces and their systems, the 

car or keel, cabin and cargo system structure, engine mounting, ACLS or device and their related 

primary attachments). For turbopropeller powered Airships those parts which could contribute to 

a catastrophic failure must also be evaluated under HCC.573(c).

In addition, the following apply:

(a) Each evaluation required by this paragraph must include: 

(1) The typical loading spectra, temperatures, humidity and corrosive and degrading agents 

expected in service; 

(2) The identification of principal structural elements and detail design points, the failure 

of which could cause catastrophic failure of the Airship; and 

(3) An analysis, supported by test evidence, of the principal structural elements and detail 

design points identified in HCC.573(a)(2). 
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(b) The service history of Airships of similar structural design, taking due account of 

differences in operating conditions and procedures, may be used in the evaluations required 

by this paragraph. 

(c) Based on the evaluations required by this paragraph, inspections or other procedures must 

be established as necessary to prevent catastrophic failure, (such as, but not limited to, 

envelope or structure, the failure of which could affect buoyancy and dynamic lift, structure 

supporting aerodynamic form of envelope, empennage, control surfaces and their systems, the 

car or keel, cabin and cargo system structure, engine mounting, ACLS or device and their 

related primary attachments), and must be included in the "Airworthiness Limitations Section 

of the Instructions for Continued Airworthiness" required by HCC.1529. 

(d) Reserved

(e) Damage-tolerance (discrete source) evaluation. 

The Airship must be capable of successfully completing a flight during which likely structural 

damage occurs as a result of: 

(1) Impact with a 10 pound (4.5 kg) bird (see HCC.631); 

(2) Uncontained fan blade impact; 

(3) Uncontained engine failure; or 

(4) Uncontained high energy rotating machinery failure. The damaged structure must be 

able to withstand the static loads (considered as ultimate loads) which are reasonably 

expected to occur on the flight. Dynamic effects on these static loads need not be 

considered. Corrective action to be taken by the pilot following the incident, such as 

limiting maneuvers, avoiding turbulence, and reducing speed, must be considered. If 

significant changes in structural stiffness or geometry, or both, follow from a structural 

failure or partial failure, the effect on damage tolerance must be further investigated. 

HCC.573 Damage tolerance and fatigue evaluation 

(a) Metallic structures: 

(1) Damage-tolerance (fail-safe) evaluation: the evaluation must include a determination of 

the probable locations and modes of damage due to fatigue, corrosion, or accidental 

damage. The determination must be shown by analysis supported by test evidence and (if 

available) service experience. Damage at multiple sites due to prior fatigue exposure must 

be included where the design is such that this type of damage can be expected to occur. 

The evaluation must incorporate repeated load and static analysis supported by test 

evidence. The extent of damage for residual strength evaluation at any time within the 

operational life must be consistent with the initial detectability and subsequent growth 

under repeated loads. The residual strength evaluation must show that the remaining 

structure is able to withstand loads (considered as static ultimate loads) corresponding to 

the following conditions: 

(i) The limit symmetrical maneuvering conditions specified in HCC.333 up to VH.

(ii) The limit gust conditions specified in HCC.341 at the specified speeds up to VH
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(iii)The limit asymmetrical conditions specified in HCC.367 at speeds up to VH

(iv)The limit yaw maneuvering conditions specified in HCC.333 at the specified speeds 

up to VH.

(v) For ACLS and directly-affected airframe structure, the limit ground loading 

conditions specified in HCC.473, 479 and 481 will apply. If significant changes in 

structural stiffness or geometry, or both, follow from a structural failure, or partial 

failure, the effect on damage tolerance must be further investigated. The residual 

strength requirements of this subparagraph (a) apply, where the critical damage is not 

readily detectable. On the other hand, in the case of damage which is readily detectable 

within a short period, smaller loads than those of subparagraphs (1)(i) to (1)(v) inclusive 

may be used by agreement with the Administrator. A probability approach may be used 

in these latter assessments, substantiating that catastrophic failure is extremely 

improbable.

(2) Fatigue (safe-life) evaluation: Compliance with the damage-tolerance requirements of 

subparagraph (1) of this HCC.573 (a) is not required if it is established for the product that 

their application for particular structure is impractical. This structure must be shown by 

analysis, supported by test evidence, to be able to withstand the repeated loads of variable 

magnitude expected during its service life without detectable cracks. Appropriate safe-life 

scatter factors must be applied. 

(b) Non-metallic structures: composite airframe structures must be evaluated under this 

subparagraph instead of HCC.573 (a). The applicant must evaluate the composite airframe 

structure, the failure of which would result in catastrophic loss of the Airship, in each 

structure related to buoyancy and static lift, empennage, their carry through and attaching 

structure, movable control surfaces and their attaching structure, car or keel, cabin, cargo 

system, engine mounting, ACLS and their related primary structures, using the damagetolerance criteria prescribed in subparagraphs (1) to (4) of this paragraph unless shown to be 

impractical. If the applicant establishes that damage-tolerance criteria are impractical for a 

particular structure, the structure must be evaluated in accordance with subparagraphs (1) and 

(6) of this paragraph. Where bonded joints are used, the structure must also be evaluated in 

accordance with subparagraph (5) of this paragraph. The effects of material variability and 

environmental conditions on the strength and durability properties of the composite materials 

must be accounted for in the evaluations required by this paragraph.

(1) It must be demonstrated by test, or by analysis supported by tests or, if available, 

service experience that the structure is capable of carrying ultimate load with damage up to 

the threshold of detectability of the inspection procedures employed. 

(2) The growth rate or no-growth of damage that may occur from fatigue, corrosion, 

manufacturing flaws or impact damage under repeated loads expected in service, must be 

established by tests or analysis supported by tests. 

(3) The structure must be shown by residual strength tests, or analysis supported by 

residual strength tests, to be able to withstand critical limit flight loads (considered as 

ultimate loads) with the extent of detectable damage consistent with the results of the 

damage tolerance evaluations. 
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(4) The damage growth, between initial detectability and the value selected for residual 

strength demonstrations, factored to obtain inspection intervals, must allow development 

of an inspection program suitable for application by operation and maintenance personnel.

(5) The limit load capacity of each bonded joint, the failure of which would result in 

catastrophic loss of the Airship, must be substantiated by one of the following methods: 

(i) The maximum disbonds of each bonded joint consistent with the capability to 

withstand the loads in subparagraph (3) of this paragraph must be determined by 

analysis, tests, or both. Disbonds of each bonded joint greater than this must be 

prevented by design features; or

(ii) Proof testing must be conducted on each production article that will apply the 

critical limit design load to each critical bonded joint; or 

(iii) Repeatable and reliable non-destructive inspection techniques must be established 

which assure the strength of each joint. 

(6) Structural components for which the damage tolerance method is shown to be 

impractical must be shown by component fatigue tests or analysis supported by tests to be 

able to withstand the repeated loads of variable magnitude expected in service. Sufficient 

component, sub-component, element, or coupon tests must be done to establish the fatigue 

scatter factor and the environmental effects. Damage up to the threshold of detectability 

and ultimate load residual strength capability must be considered in the demonstration. 

(c) Sonic fatigue strength: it must be shown by analysis, supported by test evidence, or by the 

service history of Airships of similar structural design and sonic excitation environment, that: 

(1) Sonic fatigue cracks are not probable in any part of the flight structure subject to sonic 

excitation; or: 

(2) Catastrophic failure caused by sonic cracks is not probable assuming that the loads 

prescribed in subparagraph (a)(1) of this paragraph are applied to all areas affected by 

those cracks. 

(d) Damage-tolerance (discrete source) evaluation: the Airship must be capable of continuing 

safe flight and landing after likely single structural damage occurs during a flight as a result of 

separately either one of: 

(1) Lightning (see also HCC.581) 

(2) Icing 

(3) Hail 

(4) Propeller and uncontained fan blade impact, 

(5) Uncontained engine failure, 

(6) Uncontained high energy rotating machinery failure 

(7) Whiplashing of cables breaking under load 
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(8) The damaged structure must be able to withstand the static loads (considered as 

ultimate loads) which are reasonably expected to occur at the time of the occurrence and 

during the completion of the flight. Dynamic effects on these static loads need not be 

considered. Corrective action to be taken by the pilot following the incident, such as 

limiting maneuvers, avoiding turbulence, and reducing speed, may be considered. If 

significant changes in structural stiffness or geometry, or both, follow from a structural 

failure or partial failure, the effect on damage tolerance must be further investigated. 

LIGHTNING PROTECTION 

HCC.581 Lightning protection 

a) The Airship must be protected against catastrophic effects from lightning. 

b) For metallic components, compliance with subparagraph (a) of this paragraph may be 

shown by bonding the components properly to the airframe.

c) For non-metallic components, compliance with subparagraph (a) of this paragraph may be 

shown by incorporating acceptable means of diverting the resulting electrical current. 

d) All components should be designed to minimize the effects of a strike such, that a strike 

will not endanger the Airship.
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Subpart D - Design and Construction

GENERAL

HCC.601 General 

The Airship may not have design features or details that experience has shown to be hazardous 

or unreliable. The suitability of each questionable design detail and part having an important 

bearing on safety must be established by tests. 

HCC.603 Materials 

The suitability and durability of materials used for parts, the failure of which could adversely 

affect safety, must be established on the basis of experience or test. In addition, the materials 

must conform to approved specifications (such as industry or military specifications, or 

Technical Standard Orders) that ensure their having the strength and other properties assumed in 

the design data; and take into account the effects of environmental conditions, such as 

temperature, UV-light and humidity, expected in service. 

HCC.605 Fabrication methods 

(a) The methods of fabrication used must produce a consistently sound structure. If a 

fabrication process (such as gluing, spot welding, or heat treating) requires close control to 

reach this objective, the process must be performed under an approved process specification.

(b) Each new Airship fabrication method must be substantiated by a test program.

HCC.607 Fasteners 

(a) Each removable bolt, screw, nut, pin or other removable fastener must incorporate two 

separate locking devices if: 

(1) its loss could preclude continued flight and landing within the design limitations of the 

Airship using normal pilot skill and strength; or 

(2) its loss could result in reduction in pitch or yaw control capability or response below 

that required by Subpart B of this HCC. 

(b) The fasteners specified in subparagraph (a) of this paragraph and their locking devices 

may not be adversely affected by the environmental conditions associated with the particular 

installation. 

(c) No self-locking nut may be used on any bolt subject to rotation in operation unless a nonfriction locking device is used in addition to the self-locking device. 

HCC.609 Protection of structure 

Each part of the Airship structure must: 

(a) be suitably protected against deterioration or loss of strength in service due to any cause, 

including: 

(1) Weathering; 

(2) Corrosion; and 

(3) Abrasion 
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(b) have adequate provisions for ventilation and drainage where necessary for protection 

against the hazards listed at subparagraphs (a)(1) and (a)(2). 

HCC.611 Accessibility provisions 

Means must be provided to allow inspection (including inspection of principal structural 

elements, control systems, envelope and ballonets, gas cells), replacement of parts normally 

requiring replacement, adjustment, and lubrication as necessary for continued airworthiness. The 

inspection means for each item must be practicable for the inspection interval for the item. Nondestructive inspection aids may be used to inspect structural elements where it is impracticable to 

provide means for direct visual inspection if it is shown that the inspection is effective and the 

inspection procedures are specified in the maintenance manual required by HCC.1529. 

HCC.613 Material strength properties and design values 

(a) Material strength properties must be based on enough tests of material meeting 

specifications to establish design values on a statistical basis. 

(b) The design values must be chosen to minimize the probability of structural failure due to 

material variability. Except as provided in subparagraph (e) of this paragraph, compliance 

with this subparagraph must be shown by selecting design values which assure material 

strength with the following probability: 

(1) Where applied loads are eventually distributed through a single member within an 

assembly, the failure of which would result in loss of structural integrity of the component; 

99% probability with 95% confidence. 

(2) For redundant structure, in which the failure of individual elements would result in 

applied loads being safely distributed to other load carrying members; 90% probability 

with 95% confidence. 

(c) The effects of temperature on allowable stresses used for design in an essential component 

or structure must be considered where thermal effects are significant under normal operating 

conditions. 

Accumulation of humidity in composite parts and ageing of fabric materials under UV light 

have to be taken into account for the same reason. 

(d) The strength, detail design, and fabrication of the structure must minimize the probability 

of disastrous fatigue failure, particularly at points of stress concentration.

(e) Greater design values may be used if a "premium selection" of the material is made in 

which a specimen of each individual item is tested before use to determine that the actual 

strength properties of that particular item will equal or exceed those used in design. 

HCC.619 Special factors 

The factor of safety prescribed in HCC.303 must be multiplied by the highest pertinent special 

factors of safety determined in HCC.621 through 628 for each part of the structure, the strength 

of which is: 

(a) Uncertain; or 

(b) Likely to deteriorate in service before normal replacement; or 
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(c) Subject to appreciable variability because of uncertainties in manufacturing processes or 

inspection methods. 

HCC.621 Casting factors 

(a) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this 

section must be applied in addition to those necessary to establish foundry quality control. 

The inspections must meet approved specifications. Paragraphs (c) and (d) of this section 

apply to any structural castings except castings that are pressure tested as parts of hydraulic or 

other fluid systems and do not support structural loads.

(b) Bearing stresses and surfaces. The casting factors specified in paragraphs (c) and (d) of 

this section—

(1) Need not exceed 1.25 with respect to bearing stresses regardless of the method of 

inspection used; and

(2) Need not be used with respect to the bearing surfaces of a part whose bearing factor is 

larger than the applicable casting factor.

(c) Critical castings. For each casting whose failure would preclude continued safe flight and 

landing of the airship or result in serious injury to occupants, the following apply:

(1) Each critical casting must—

(i) Have a casting factor of not less than 1.25; and

(ii) Receive 100 percent inspection by visual, radiographic, and magnetic particle or 

penetrant inspection methods or approved equivalent nondestructive inspection 

methods. 

(2) For each critical casting with a casting factor less than 1.50, three sample castings must 

be static tested and shown to meet—

(i) The strength requirements of HCC.305 at an ultimate load corresponding to a casting 

factor of 1.25; and

(ii) The deformation requirements of HCC.305 at a load of 1.15 times the limit load.

(3) Examples of these castings are structural attachment fittings, parts of flight control 

systems, control surface hinges and balance weight attachments, seat, berth, safety belt, 

and fuel and oil tank supports and attachments, and cabin pressure valves.

(d) Noncritical castings. For each casting other than those specified in paragraph (c) of this 

section, the following apply:

(1) Except as provided in paragraphs (d)(2) and (3) of this section, the casting factors and 

corresponding inspections must meet the following table:
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Casting factor Inspection

2.0 or more 100 percent visual.

Less than 2.0 but

more than 1.5

100 percent visual, and magnetic particle or penetrant or 

equivalent nondestructive inspection methods.

1.25 through 1.50 100 percent visual, magnetic particle or penetrant, and 

radiographic, or approved equivalent nondestructive 

inspection methods.

(2) The percentage of castings inspected by nonvisual methods may be reduced below that 

specified in paragraph (d)(1) of this section when an approved quality control procedure is 

established.

(3) For castings procured to a specification that guarantees the mechanical properties of the 

material in the casting and provides for demonstration of these properties by test of 

coupons cut from the castings on a sampling basis—

(i) A casting factor of 1.0 may be used; and

(ii) The castings must be inspected as provided in paragraph (d)(1) of this section for 

casting factors of “1.25 through 1.50” and tested under paragraph (c)(2) of this section.

HCC.623 Bearing factors 

(a) Except as provided in subparagraph (b) of this paragraph, each part that has clearance (free 

fit), and that is subject to pounding or vibration, must have a bearing factor large enough to 

provide for the effects of normal relative motion. 

(b) No bearing factor need be used for a part for which any larger special factor is prescribed 

HCC.625 Fitting factors 

For each fitting (a part or terminal used to join one structural member to another), the following 

apply. 

(a) For each fitting, the strength of which, is not proven by limit and ultimate load tests in 

which actual stress conditions are simulated in the fitting and surrounding structures, a fitting 

factor of at least 1.15 must be applied to each part of 

(1) The fitting; 

(2) The means of attachment, and, 

(3) The bearing on the joined members. 

(b) No fitting factor needs to be used for joints made under approved practices and based on 

comprehensive test data (such as continuous joints in metal plating, welded joints, and scarf 

joints in wood). 

(c) For each integral fitting, the part must be treated as a fitting up to the point at which the 

section properties become typical of the member. 

(d) For each designated flight seat, berth and safety belt and harness, its attachment to the 

structure must be shown, by analysis, tests or both, to be able to withstand the inertia forces 

prescribed in HCC.561 multiplied by a fitting factor of 1.33. 
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HCC.628 Rope, wire, cable and chain factors 

(a) For tethers and mooring ropes, wires or cables that are not passed through pulleys, the 

following factors apply for limit loads:

(1) 3 for calculated breaking strength;

(2) 2.5 for breaking strength established by tests.

(b) For ropes, wires or cables of hoists and winches etc. the factors must be established in 

accordance with HCC.603. Load collectives and kinds of operation are to be considered.

(c) For ropes, wires or cables which are stressed at low level as shown by calculation and for 

which the factors are not established in (b), a factor of 3.4 against tested ultimate load applies.

HCC.631 Birdstrike

If VH is greater than 100 kts, the Airship must be designed to assure capability of continued safe 

flight and landing after impact with a 10 pound (4.5 kg) bird, when the velocity of the Airship 

(relative to the bird along the flight path of the Airship) is equal to VH. Compliance may be 

shown by analysis based on tests carried out on sufficiently representative structures of similar 

design.

CONTROL SURFACES 

HCC.651 Proof of strength 

(a) Limit load tests of control surfaces are required. These tests must include the horn or 

fitting to which the control system is attached. 

(b) Compliance with the special factors requirements of HCC.619 through HCC.628 and 

HCC.657 for control surface hinges must be shown by analysis or individual load tests. 

(c) In structural analyses, rigging loads due to wire bracing must be accounted for in a rational 

or conservative manner. 

HCC.655 Installation 

(a) Movable tail surfaces must be installed so that there is no interference between any 

surfaces or their bracing when one surface is held in its extreme position and the others are 

operated through their full angular movement.

(b) If an adjustable stabilizer is used, it must have stops that will limit its range of travel to 

that allowing safe flight and landing. 

HCC.657 Hinges 

(a) Control surface hinges, except ball and roller bearing hinges, must have a factor of safety 

of not less than 6.67 with respect to the ultimate bearing strength of the softest material used 

as a bearing. 

(b) For ball or roller bearing hinges, the approved rating of the bearing may not be exceeded. 

(c) Hinges must have enough strength and rigidity for loads parallel to the hinge line. 
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HCC.659 Mass balance 

The supporting structure and the attachment of concentrated mass balance mass used on control 

surfaces must be designed for 

(a) 24 g normal to the plane of the control surface; 

(b) 12 g fore and aft; 

(c) 12 g parallel to the hinge line. 

CONTROL SYSTEMS

HCC.671 General 

(a) Each control and control system must operate with ease, smoothness and positiveness 

appropriate to its functions. 

(b) Controls must be arranged and identified to provide for convenience in operation and to 

prevent the possibility of confusion and subsequent inadvertent operation. 

(c) The airship must be shown by analysis, test, or both, to be capable of continued safe flight 

and landing after any of the following failures or jamming in the flight control system and 

surfaces (including trim, lift, drag and artificial feel systems) within the normal flight 

envelope, without requiring exceptional piloting skill or strength. Probable malfunctions must 

have only minor effects on airship operation and must be capable of being readily 

counteracted by the pilot:

(1) Any single failure not shown to be extremely improbable, excluding jamming, (for 

example, disconnection or failure of mechanical elements, or structural failure of hydraulic 

components, such as actuators, control spool housing, and valves). 

(2) Any combination of failures not shown to be extremely improbable, excluding 

jamming (for example dual electrical or hydraulic system failures, or any single failure in 

combination with any probable hydraulic or electrical failure).

(3) Any jam in a control position normally encountered during cargo loading/unloading, 

passenger boarding/unboarding, take-off, climb, cruise, normal turns, descent and landing 

unless the jam is shown to be extremely improbable or can be alleviated. A runaway of a 

flight control to an adverse position and jam must be accounted for if such runaway and 

subsequent jamming is not extremely improbable.

(d) As required by HCC.143 the Airship must be capable of maintaining a statically stable 

condition and have sufficient control of attitude and altitude to allow a safe descent if all 

propulsive engines fail. Compliance with this requirement may be shown by analysis where 

that method has been shown to be reliable. 

(e) Components of the gas and air system, and control surfaces, including valves, 

mechanisms, cables, actuators, hinges, bearings and any other related moving component of 

these systems, will be shown to operate normally in the environmental conditions requested 

for operation, this could include but not limited to rain, frost, icing and dust in the extreme 

that is possible to be encountered in operation.
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HCC.672 Stability augmentation and automatic and power-operated systems 

If the functioning of stability augmentation or other automatic or power-operated system is 

necessary to show compliance with flight characteristics requirements, the system must comply 

with HCC.671 and the following: 

(a) A warning which is clearly distinguishable to the pilot under expected flight conditions 

must be provided for any failure in the stability augmentation system or in any other 

automatic or power-operated system which could result in an unsafe condition if the pilot is 

unaware of the failure. Warning systems must not activate the control systems.

(b) The design of the stability augmentation system or of any other automatic or poweroperated system must allow initial counteraction of failures without requiring exceptional 

pilot skill or strength, by overriding the failure by moving the flight controls in the normal 

sense, and by deactivating the failed system. 

(c) It must be shown that after any single failure of the stability augmentation system or any 

other automatic or power-operated system: 

(1) The Airship is safely controllable when the failure or malfunction occurs at any speed 

or altitude within the approved operating limitations; and: 

(2) The controllability and maneuverability requirements are met within a practical 

operational flight envelope (for example, speed, altitude and normal acceleration 

configurations) which is described in the Airship Flight Manual.

HCC.675 Stops 

(a) Each control system must have stops that positively limit the range of motion of each 

movable aerodynamic surface controlled by the system. 

(b) Each stop must be located so that wear, slackness, or take-up adjustments will not 

adversely affect the control characteristics of the Airship because of a change in the range of 

surface travel. 

(c) Each stop must be able to withstand any loads corresponding to the design conditions for 

the control system. 

HCC.677 Trim Systems 

(a) Trim systems include ballonets, ballast transfer, trim tabs on aerodynamic control surfaces 

or any other system which directly affects the long-term, in-flight, attitude of the Airship. 

Proper precautions must be taken to prevent inadvertent, improper, or abrupt trim operation. 

(b) Static trim 

(1) When ballonets are used for trimming, the pilot must have means for determining the 

fullness of all ballonets. In addition a means in accordance with HCC.1322 must be 

provided, alerting if the ballonets are completely empty or full. There must be means to 

determine the intermediate conditions of the ballonets. 

(2) When ballast transfer is used for trimming, the pilot must be capable of determining 

any intermediate condition of the ballast transfer system.

(c) Aerodynamic trim: 
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(1) When trim tabs are used, there must be means near the trim control to indicate to the 

pilot the direction of trim control movement relative to Airship motion. In addition, there 

must be means to indicate to the pilot the position of the trim device with respect to the 

range of adjustment. This means must be visible to the pilot and must be located and 

designed to prevent confusion. 

(2) Tab controls must be irreversible unless the tab is properly balanced and has no unsafe 

flutter characteristics. Irreversible tab systems must have adequate rigidity and reliability in 

the portion of the system from the tab to the attachment of the irreversible unit to the 

Airship structure.

HCC.679 Control system gust locks 

If there is a device to prevent damage to the control surfaces (including tabs), and to the control 

system, from gusts striking the Airship while it is on the ground and moored and if the device, 

when engaged, prevents normal operation of the control surfaces by the pilot, it must: 

(a) Give unmistakable warning to the pilot when the lock is engaged; 

(b) Prevent the lock from inadvertently engaging in flight. 

HCC.681 Limit load static tests 

(a) Compliance with the limit load requirements of this HCC must be shown by tests in 

which: 

(1) The direction of the test loads produces the most severe loading in the control system, 

and; 

(2) Each fitting, pulley, and bracket used in attaching the system to the main structure is 

included. 

(b) Compliance must be shown (by analysis or individual load tests) with the special factor 

requirements for control system joints subject to angular motion. 

HCC.683 Operation tests 

(a) It must be shown by operation tests that, when the controls are operated from the crew 

compartment or another control station with the system loaded as prescribed in subparagraph 

(b) of this paragraph, the system is free from: 

(1) Jamming; 

(2) Excessive friction; 

(3) Excessive deflection. 

(b) The prescribed test loads are: 

(1) For the entire system, loads corresponding to the limit airloads on the appropriate 

surface, or the limit pilot forces, whichever are less;

(2) For secondary controls, loads not less than those corresponding to the maximum pilot 

effort established under HCC.405. 
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HCC.685 Control system details 

(a) Each detail of each control system must be designed and installed to prevent jamming, 

chafing, and interference from cargo, passengers, loose objects, or the freezing of moisture. 

(b) There must be means to prevent the entry of foreign objects into places where they would 

jam a control system. 

(c) There must be means to prevent the rubbing of cables or tubes against other parts. 

(d) Each element of a control system must have design features, or, where impractical, must 

be distinctively and permanently marked, to minimize the possibility of incorrect assembly 

that could result in malfunctioning of the control system.

HCC.693 Joints

Control system joints (in push-pull systems) that are subject to angular motion, except those in 

ball and roller bearing systems, must have a special factor of safety of not less than 3.33 with 

respect to the ultimate bearing strength of the softest material used as a bearing. This factor may 

be reduced to 2.0 for joints in cable control systems. For ball or roller bearings, the approved 

ratings may not be exceeded. 

HCC.697 Lift and Drag Devices, Controls

Each lift and drag device control must be designed and located to make inadvertent operation 

improbable. Lift and drag devices intended for ground operation only must have means to 

prevent the inadvertent operation of their controls in flight if that operation could be hazardous.

HCC.699 Lift and Drag Device Indicator

Lift and drag devices (other than flaps and leading edge devices) must have a device to warn the 

pilot that the control is operated, unless it is demonstrated that operation of the control is not 

hazardous.

AIR CUSHION LANDING SYSTEM (ACLS)

HCC.721 General 

(a) For Hybrid Airships equipped with ACLS and designed for running takeoff and landing 

the requirements of this subparagraph and HCC.723 for the ACLS apply:

(1) The main ACLS must be designed so that if it fails due to overloads during takeoff and 

landing the failure mode is not likely to cause the spillage of enough fuel from any part of 

the fuel system to constitute a fire hazard.

(2) Each Airship must be designed so that, with the Airship under control, it can be landed 

with any one or more ACLS pad not extended without sustaining a structural component 

failure that is likely to cause the spillage of enough fuel to constitute a fire hazard.

(b) Compliance with the provisions of this paragraph may be shown by analysis or tests, or 

both.
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HCC.723 Shock absorption tests 

(a) The ACLS dynamic characteristics used for design must be validated by energy absorption 

tests. The dynamic characteristics must be substantiated for the range of landing conditions, 

Airship configurations, and service variations expected in operation. 

(1) The configurations subjected to energy absorption tests must include at least the 

maximum static landing weight or the maximum static takeoff weight, whichever produces 

the greater value of landing impact energy.

(2) The test attitude of the ACLS unit and the application of appropriate drag loads during 

the test must simulate the Airship landing conditions in a manner consistent with the 

development of rational or conservative limit loads.

(3) Changes in previously approved design weights and minor changes in design may be 

substantiated by analysis based on previous tests conducted on the same basic ACLS that 

has similar energy absorption characteristics.

(b) The ACLS must not fail, but may yield, in the test showing its reserve energy absorption 

capacity, simulating a descent velocity of 1.2 times the limit descent velocity. The elastic 

behavior of the Airship may be taken into account.

HCC.729 Retraction mechanism 

(a) General: for Hybrid Airships designed for running take-off and landing and equipped with 

retractable ACLS, the following apply.

(1) Each ACLS retracting mechanism and its supporting structure must be designed for 

maximum flight-load factors with the pad retracted and must be designed for the 

combination of friction, inertia, and air loads, occurring during retraction at any airspeed 

up to VLO, selected for the product;

(2) The ACLS and retracting mechanism must withstand flight loads, including loads 

resulting from all yawing conditions specified in the structure subpart with the ACLS 

extended at any speed up to VLO.

(b) Emergency operation: unless it can be demonstrated that a safe landing can be made with 

the pads retracted, there must be a means to extend the ACLS in the event of either:

(1) Any reasonably probable failure in the normal ACLS operation system; or

(2) Any reasonably probable failure in a power source that would prevent the operation of 

the normal ACLS operation system.

(c) Operational test: the proper functioning of the retracting mechanism must be shown by 

operational tests.

(d) Position indicator: there must be a ACLS position indicator (as well as necessary devices 

to actuate the indicator) or other means to inform the pilot that the ACLS is secured in the 

extended (or retracted) position. If switches are used, they must be located and coupled to the 

ACLS pneumatic system in a manner that prevents an erroneous indication of fully deployed 

if the ACLS is not in the fully deployed position, or retracted if the ACLS is not in the fully 

retracted position. The switches must be of a type and location which cannot be affected by 

the freezing of atmospheric water vapor on to the switch system.
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(e) ACLS warning: an aural or equally effective device that functions continuously when the 

ACLS is not fully deployed and the altitude of the Airship is less than 100 ft above ground 

level. If the altitude sensor portion of the warning system fails, the warning system must be 

designed to activate until the ACLS is fully deployed.

(f) If the ACLS retraction system uses a cable system: 

(1) Each cable, cable fitting, turnbuckle, splice, and pulley use in ACLS retraction system 

must be approved. In addition: 

(i) No cable smaller than 0.125 in (3.2 mm) diameter may be used in the retraction 

system; and

(ii) Each cable system must be designed so that there will be no hazardous change in 

cable tension throughout the range of travel under operating conditions and temperature 

variations.

(2) Each kind and size of pulley must correspond to the cable with which it is used. Pulleys 

and sprockets must have closely fitted guards to prevent the cables and chains from being 

displaced or fouled. Each pulley must lie in the plane passing through the cable so that the 

cable does not rub against the pulley flange.

(3) Fairleads must be installed so that they do not cause a change in cable direction of more 

than three degrees.

(4) Clevis pins subject to load or motion and retained only by cotter pins may not be used 

in the retraction system. 

(5) Turnbuckles must be attached to parts having angular motion in a manner that will 

positively prevent binding throughout the range of travel.

(6) There must be provisions for visual inspection of fairleads, pulleys, terminals, and 

turnbuckles.

PERSONNEL AND CARGO ACCOMMODATIONS 

HCC.771 Pilot compartment 

(a) The compartment and its equipment must allow each pilot to perform his duties without 

unreasonable concentration or fatigue; 

(b) Where the flight crew is separated from the passengers there must be means for 

communication between flight crew and the passengers; 

(c) The combined probability of propeller failure and time a propeller could be positioned 

where its spin plane is +/- 5 degrees to the controls referenced in HCC.779 (excluding cables 

and control rods) or minimum flight crew (established under HCC.1523) is extremely 

improbable (and when in the non-transition positions for vectored thrust). 

(d) If provision is made for a second pilot, the Airship must be controllable with equal safety 

from either pilot seat. 

(e) The pilot compartment must be constructed so that, when flying in rain or snow, it will not 

leak in a manner that will distract the crew or harm the structure. 
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(f) Vibration and noise characteristics of the flightdeck equipment may not interfere with safe 

operation of the Airship.

HCC.772 Flight crew compartment doors 

Reserved

HCC.773 Pilot compartment view 

(a) Non-precipitation conditions: for non-precipitation conditions, the following apply:

(1) Each pilot compartment must be arranged to give the pilots a sufficiently extensive, 

clear, and undistorted view, to enable them to safely perform any maneuvers within the 

operating limitations of the Airship, including ground maneuvering, takeoff, approach and 

landing.

(2) Each pilot compartment must be free of glare and reflection that could interfere with 

the normal duties. This must be shown in day and night flight tests under non-precipitation 

conditions. 

(b) Precipitation conditions: for precipitation conditions, the following apply: 

(1) The Airship must have a means to maintain a clear portion of the windshield during 

precipitation conditions, sufficient for the crew to have a sufficiently extensive view along 

the flight path in normal flight attitudes of the Airship. This means must be designed to 

function, without continuous attention on the part of the crew, in: 

(i) Heavy rain at speeds up to VH

(ii) The icing conditions specified in HCC.1419 if certification with ice protection 

provisions is requested. 

(2) No single failure of the systems used to provide the view required by sub-paragraph 

(b)(1) of this paragraph must cause the loss of that view by the crew in the specified 

precipitation conditions. 

(3) The pilot must have a window that is openable under the conditions prescribed in subparagraph (b)(1) of this paragraph and gives sufficient protection from the elements against 

impairment of the pilot's vision; 

(c) Internal windshield and window fogging: the Airship must have a means to prevent 

fogging to the internal portions of the windshield and window panels over an area which 

would provide the visibility specified in sub-paragraph (a) of this paragraph under all internal 

and external ambient conditions, including precipitation conditions, in which the Airship is 

intended to be operated. 

(d) On Airships designed for running takeoff and landing fixed markers or other guides must 

be installed at each pilot station to enable the pilots to position themselves in their seats for an 

optimum combination of outside visibility and instrument scan. If lighted markers or guides 

are used they must comply with the requirements specified in HCC.1381. 

HCC.775 Windshields and windows 

(a) Windshields and windows must be made of non-splintering material. 
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(b) Windshields and windows must have a luminous transmittance value of not less than 70% 

when used for: 

(1) Operating crews view when seated in the normal flight position 

(2) Propeller and empennage inspection during flight 

(3) Loading or unloading 

(4) Mooring 

(5) Rigging 

(c) An openable window at the pilot and co-pilot station must be provided.

HCC.777 Cockpit controls 

(a) Each cockpit control must be located and (except where its function is obvious) identified 

to provide convenient operation and to prevent confusion and inadvertent operation. 

(b) Controls must be located and arranged so that the crew members, when seated and 

wearing harness, have full and unrestricted movement of each control without interference. 

(c) Identical engine and thruster controls for each engine/thruster must be located to prevent 

confusion as to the engines/thrusters they control. Grouped controls per engine/thruster must 

be clearly distinguishable and recognizable by size, shape and color. 

(d) On Airships designed for running takeoff and landing, the ACLS control must be located 

forward of the throttles. 

(e) Identical controls for gas (cells), ballast, ballonets and fuel must be located and arranged 

so that the pilot can see and reach it without moving any seat or primary flight control. 

(f) All control knobs for a particular function must be so shaped and colored that there is a 

clear contrast with control knobs for a different function and with the surrounding flight deck. 

Control knobs that are utilized for the same functions as utilized for airplanes will comply 

with the shape and color provisions of 14 CFR parts 23.777(g) and 25.781.

HCC.779 Motion and effect of cockpit controls 

Cockpit controls must be designed so that they operate in accordance with the movement and 

actuation in Table 9 of Appendix A. Wherever practicable, the sense of motion involved in the 

operation of other controls must correspond to the sense of the effect of the operation upon the 

Airship or upon the part operated. 

HCC.783 Doors 

(a) Each closed cabin with passenger accommodations must have at least one adequate and 

easily accessible external door.

(b) Passenger doors must not be located with respect to any propeller disk or any other 

potential hazard so as to endanger persons using the door.

(c) Each external passenger or crew door must comply with the following requirements:

(1) There must be a means to lock and safeguard the door against inadvertent opening 

during flight by persons, by cargo, or as a result of mechanical failure.
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(2) The door must be openable from the inside and the outside when the internal locking 

mechanism is in the locked position.

(3) There must be a means of opening which is simple and obvious and is arranged and 

marked inside and outside so that the door can be readily located, unlocked, and opened, 

even in darkness.

(4) The door must meet the marking requirements of HCC.811.

(5) The door must be reasonably free from jamming as a result of fuselage deformation in 

an emergency landing.

(6) Auxiliary locking devices that are actuated externally to the airship may be used but 

such devices must be overridden by the normal internal opening means.

(d) In addition, each external passenger or crew door, for airships having a seating capacity of 

19 or less excluding pilots, must comply with the following requirements:

(1) Each door must be openable from both the inside and outside, even though persons 

may be crowded against the door on the inside of the airship.

(2) If inward opening doors are used, there must be a means to prevent occupants from 

crowding against the door to the extent that would interfere with opening the door.

(3) Auxiliary locking devices may be used.

(e) Each external door for airships having a seating capacity of 19 or less excluding pilots, 

must comply with the following requirements:

(1) There must be a means to lock and safeguard each external door, including cargo and 

service type doors, against inadvertent opening in flight, by persons, by cargo, or as a 

result of mechanical failure or failure of a single structural element, either during or after 

closure.

(2) There must be a provision for direct visual inspection of the locking mechanism to 

determine if the external door, for which the initial opening movement is not inward, is 

fully closed and locked. The provisions must be discernible, under operating lighting 

conditions, by a crewmember using a flashlight or an equivalent lighting source.

(3) There must be a visual warning means to signal a flight crewmember if the external 

door is not fully closed and locked. The means must be designed so that any failure, or 

combination of failures, that would result in an erroneous closed and locked indication is 

improbable for doors for which the initial opening movement is not inward. 

(f) In addition, for airships having a seating capacity of 19 or less excluding pilots, the 

following requirements apply:

(1) Each passenger entry door must qualify as a floor level emergency exit. This exit must 

have a rectangular opening of not less than 24 inches wide by 48 inches high, with corner 

radii not greater than one-third the width of the exit.

(2) If an integral stair is installed at a passenger entry door, the stair must be designed so 

that, when subjected to the inertia loads resulting from the ultimate static load factors in 
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HCC.561(b)(2) and following the collapse of one or more ACLS pads, it will not reduce 

the effectiveness of emergency egress through the passenger entry door.

(g) If lavatory doors are installed, they must be designed to preclude an occupant from 

becoming trapped inside the lavatory. If a locking mechanism is installed, it must be capable 

of being unlocked from outside of the lavatory.

HCC.784 Passenger compartment windows 

Each openable passenger compartment window must comply with the following requirements: 

(a) there must be a means to lock and safeguard each openable window against inadvertent 

opening in flight, by persons or failure of a single structural element, either during or after 

closure; and: 

(b) there must be adequate provisions to prevent persons falling out or items being thrown out 

of an opened window. 

HCC.785 Seats, berths, safety belts and harnesses 

There must be a seat or berth for each occupant. 

(a) Each seat, berth, designated as occupiable during take-off, landing, ground maneuvers and 

mooring and emergency situations, its supporting structure, its safety belt, and harness must 

be designed for occupants weighing at least 215 pounds (98 kg) and for the maximum load 

factors corresponding to the specified flight and ground load conditions, including emergency 

landing conditions.

(b) Each seat, berth, safety belt and harness must be approved against appropriate 

requirements depending on function. 

(c) Each pilot seat must be designed for the reactions resulting from the application of pilot 

forces to the primary flight controls prescribed in Table 2 of Appendix A. 

(d) Each crew member seat at a flight compartment station and each passenger compartment 

crew member seat designated for use during takeoff and landing shall have a shoulder 

harness. 

(e) Each berth installed parallel to the longitudinal axis of the Airship must be designed so 

that the forward part has a padded end-board, canvas diaphragm, or equivalent means that can 

withstand the static load reaction of the occupant when the occupant is subjected to the 

forward inertia forces prescribed in HCC.561. In addition each berth must have an approved 

safety belt and may not have corners or other parts likely to cause serious injury to a person 

occupying it during emergency conditions. 

(f) Proof of compliance with the strength and deformation requirements of this paragraph for 

seats, berths, and safety belts, approved as part of the type design and for their installation, 

may be shown by:

(1) Structural analysis, if the structure conforms to conventional aircraft types for which 

existing methods of analysis are known to be reliable; or 

(2) A combination of structural analysis and static load tests to limit loads; or 

(3) Static load tests to ultimate loads. 
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(g) Each occupant must be protected from serious head injury when subjected to the inertia 

loads resulting from these load factors by a safety belt. Each Safety belt must be equipped 

with a metal to metal latching device. Each safety belt must incorporate a lap belt and 

shoulder harness.

(h) Each seat located in the passenger compartment and designated for use during takeoff and 

landing by a flight attendant must be: 

(1) Near a required floor level emergency exit, except that another location is acceptable if 

the emergency egress of passengers would be enhanced with that location. A flight 

attendant seat must be located adjacent to each floor level exit. Other flight attendant seats 

must be evenly distributed among the required floor level emergency exits to the extent 

feasible. 

(2) To the extent possible, without compromising proximity to a required floor level 

emergency exit, located to provide a direct view of the cabin area for which the flight 

attendant is responsible. 

(3) Positioned so that the seat will not interfere with the use of a passageway or exit when 

the seat is not in use. 

(4) Located to minimize the probability that occupants would suffer injury by being struck 

by items dislodged from service areas, stowage compartments, or service equipment.

(5) Either forward or rearward facing with an energy absorbing rest that is designed to 

support the arms, shoulders, head and spine. 

(6) Equipped with a restraint system consisting of a combined safety belt and shoulder 

harness unit with a single point release. There must be means to secure each restraint 

system when not in use to prevent interference with rapid egress in an emergency. 

(i) There must be a means to secure each safety belt, when not in use, so as to prevent 

interference with the operation of the Airship and with rapid egress in an emergency. 

(j) The compartment area surrounding each seat, bed or bunk, including the structure, interior 

walls, instrument panel, control wheel, pedals, and seats, within striking distance of the 

occupants head or torso (with the safety belt fastened), must be free of potentially injurious 

objects, sharp edges, protuberances, and hard surfaces. If energy absorbing designs or devices 

are used to meet this requirement, they must protect the occupant from serious injury when 

the occupant experiences the ultimate inertia forces prescribed in HCC.561. 

(k) Each seat track must be fitted with stops to prevent the seat from sliding off the track. 

(l) All compartments and areas accessible in flight must be free of potentially injurious 

objects, sharp edges, protuberances and hard surfaces. If energy absorbing designs or devices 

are used to meet this requirement, they must protect the occupant from serious injury when 

the occupant experiences inertia forces due to normal gusts. 

(m) In turbulence conditions it must be impossible for an unrestrained person to fall through 

large openings in the structure (e.g. sightseeing windows).

(n) There must be means installed for crew members acting in areas not accessible to 

untrained persons to carry out their tasks safely. During internal/external inspection, 
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maintenance or repair catwalks, rails, hatches and ladders it must be possible to become 

quickly linked-up to a restrain system. 

(o) When stressing seat attachments, seat rails etc. the mass of the seat in addition to that of 

the passengers shall be taken into account. The fitting factors of HCC.625 shall be applied. 

(p) All other seats and compartment areas must be equipped with retention means (seat belts, 

seat back handholds, grips, rails) to ensure that persons be retained during reasonably 

expectable in-flight occurrences (refer to AFM), unless it can be shown that persons can 

steady themselves without difficulty. 

HCC.786 Areas accessible during flight 

For crew members patrolling the interior of the Airship and working outside the passenger or 

flight compartments, even outside the hull, safety provisions must be provided, such as access 

(doors, safe catwalks and ladders), handrails and grips, escape routes, fire detection and 

extinguishers, emergency lighting, axes, knives and onboard communication. 

HCC.787 Baggage and cargo compartment 

Each compartment for the stowage of cargo, baggage, ballast, carry-on articles and equipment 

(such as life rafts) and any other stowage compartment: 

(a) must be designed for its placarded maximum mass of contents and the critical load 

distribution at the maximum load factors corresponding to the flight limit loads determined in 

HCC.321 through HCC.371 and ground limit loads determined in HCC.471 through 

HCC.481.

(b) must contain provisions to prevent shifting of contents and to protect any controls, wiring 

lines, equipment or accessories during flight and ground conditions. 

(c) under the emergency landing conditions of HCC.561, baggage and cargo compartments 

must: 

(1) Be positioned such that if the contents break loose they are unlikely to cause injury to 

the occupants, cause damage to fuel tanks, or restrict any of the escape facilities provided 

for use after an emergency landing; or: 

(2) Have sufficient strength to withstand the conditions specified in HCC.561, including 

the means of restraint and their attachments required by subparagraph (b) of this paragraph. 

Sufficient strength must be provided for the maximum authorized mass of cargo and 

baggage at the critical loading distribution.

(d) If cargo compartment lamps are installed, each lamp must be installed so as to prevent 

contact between lamp bulb and cargo. 

HCC.789 Retention of items of mass in passenger and crew compartments and galleys 

(a) Means must be provided to prevent each item of mass (that is part of the Airship type 

design) in a passenger or crew compartment or galley from becoming a hazard by shifting 

under the appropriate maximum load factors corresponding to the specified flight and ground 

load conditions, and to the emergency landing conditions of HCC.561 (b).
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(b) Each interphone restraint system must be designed so that when subjected to the load 

factors specified in HCC.561 (b), the interphone and megaphone, if installed, will remain in 

its stowed position. 

HCC.791 Passenger information signs and placards 

(a) If smoking is to be prohibited, there must be at least one placard so stating that is legible to 

each person seated in the cabin. If smoking is to be allowed, and if the crew compartment is 

separated from the passenger compartment, there must be at least one sign notifying when 

smoking is prohibited. Signs which notify when smoking is prohibited must be installed so as 

to be operable from either pilot's seat and, when illuminated, must be legible under all 

probable conditions of cabin illumination to each person seated in the cabin. 

(b) Signs that notify when occupants are to return to their designated flight seats and seat belts 

are to be fastened must be installed so as to be operable from either pilot's seat and, when 

illuminated, must be legible under all probable conditions of illumination to each person in 

the cabin and to crew members when performing duties in normally occupiable areas. A 

placard must be located on or adjacent to the door of each receptacle used for the disposal of 

flammable waste materials to indicate that use of the receptacle for disposal of cigarettes, etc., 

is prohibited.

(c) Lavatories must have "NO SMOKING" or "NO SMOKING IN LAVATORY" placards 

positioned adjacent to each ashtray. The placards must have red letters at least 0.5 in (12.7 

mm) high on a white background of at least 1 in (25.4 mm) high. (a "NO SMOKING" symbol 

may be included on the placard.) 

HCC.793 Floor surfaces 

The floor surface of all areas which are likely to become wet in service must have slip resistant 

properties. 

HCC.801 Ditching 

(a) If certification with ditching provisions is requested, the Airship must meet the 

requirements of this paragraph and HCC.1411 and 1415(a). 

(b) Each practicable design measure, compatible with the general characteristics of the 

Airship, must be taken to minimize the probability that in an emergency landing on water, the 

behavior of the Airship would cause immediate injury to the occupants or would make it 

impossible for them to escape.

(c) The probable behavior of the Airship in a water landing must be investigated in a model 

test or by comparison with similar configurations for which the ditching characteristics are 

known. Different configurations, heaviness and center of gravity have to be considered. 

(d) It must be shown that under reasonably probable water conditions, the flotation time of the 

Airship will allow the occupants to leave the Airship and enter the liferafts required by 

HCC.1415. If compliance with this provision is shown by buoyancy and trim computations, 

appropriate allowances must be made for probable structural damage and leakage.
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HCC.803 Emergency evacuation 

(a) Each crew and passenger compartment must have easy access to at least two independent 

means to allow rapid evacuation in emergency such as crash landings, with the ACLS (if 

applicable) extended or retracted, considering the possibility of the Airship on fire. 

(b) A technique shall be established and published in the Airship Flight Manual for rapid 

evacuation of the Airship on land and on water by all occupants in such an emergency, 

considering the possibility of (still) running engines/propellers. 

(c) The technique shall include the crew procedures for controlling passenger evacuation. 

(d) When following this technique, the operation of the Airship's controls, including the 

emergency deflation means shall be such that, during the evacuation, the Airship will not 

leave the ground to an extent that would prevent the occupants leaving the Airship, and the 

envelope must not deflate at a rate that would permit the envelope to entrap any occupant. 

(e) The technique shall include any special precautions to be taken in surface wind speeds 

between zero and the maximum in which operation is permitted. 

(f) If the occurrence of fire hazard for the passenger and crew compartments in crash landings 

cannot be considered extremely improbable, it must be shown that the maximum passengers 

capacity, including the number of crew members required by the operating rules for which 

certification is requested, can be evacuated from the Airship to the ground under simulated 

emergency conditions within 90 seconds. Compliance with this requirement must be shown 

by actual demonstration under simulated night conditions using only the emergency exits on 

the most critical side of the Airship. The participants must be representative of average airline 

passengers with no prior practice or rehearsal for the demonstration, although standard 

briefings are permissible. 

HCC.807 Emergency exits 

(a) Number and location. Emergency exits must be located to allow escape without crowding 

in any probable crash attitude. The airship must have at least the following emergency exits: 

(1) For all airships with a seating capacity of two or more at least one emergency exit on 

the opposite side of the cabin from the main door specified in HCC.783. 

(2) Reserved.

(3) If the pilot compartment is separated from the cabin by a door that is likely to block the 

pilot's escape in a minor crash, there must be an exit in the pilot's compartment. The 

number of exits required by paragraph (a)(1) of this section must then be separately 

determined for the passenger compartment, using the seating capacity of that compartment. 

(4) Emergency exits must not be located with respect to any propeller disk or any other 

potential hazard so as to endanger persons using that exit.

(b) Type and operation. Emergency exits must be movable windows, panels, or external 

doors, openable from both inside and outside the airship, that provide a clear and unobstructed 

opening large enough to admit a 19-by-26-inch ellipse. Auxiliary locking devices used to 

secure the airship must be designed to be overridden by the normal internal opening means. 
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The inside handles of emergency exits that open outward must be adequately protected 

against inadvertent operation. In addition, each emergency exit must--

(1) Be readily accessible, requiring no exceptional agility to be used in emergencies; 

(2) Have a method of opening that is simple and obvious; 

(3) Be arranged and marked for easy location and operation, even in darkness; 

(4) Have reasonable provisions against jamming by fuselage deformation.

(c) Tests. The proper functioning of each emergency exit must be shown by tests. 

(d) Doors and exits. In addition, for airships having a seating capacity of 19 or less excluding 

pilots, the following requirements apply:

(1) In addition to the passenger-entry door--

(i) For an airship with a total passenger seating capacity of 15 or fewer, an emergency 

exit, as defined in paragraph (b) of this section, is required on each side of the cabin; 

and 

(ii) For an airship with a total passenger seating capacity of 16 through 19, three 

emergency exits, as defined in paragraph (b) of this section, are required with one on 

the same side as the passenger entry door and two on the side opposite the door.

(2) A means must be provided to lock each emergency exit and to safeguard against its 

opening in flight, either inadvertently by persons or as a result of mechanical failure. In 

addition, a means for direct visual inspection of the locking mechanism must be provided 

to determine that each emergency exit for which the initial opening movement is outward 

is fully locked. 

(3) Each required emergency exit, except floor level exits, if not less than six feet from the 

ground, must be provided with an acceptable means to assist the occupants to descend to 

the ground. Emergency exits must be distributed as uniformly as practical, taking into 

account passenger seating configuration. 

(4) Unless the applicant has complied with paragraph (d)(1) of this section, there must be 

an emergency exit on the side of the cabin opposite the passenger entry door, provided 

that--

(i) For an airship having a passenger seating configuration of nine or fewer, the 

emergency exit has a rectangular opening measuring not less than 19 inches by 26 

inches high with corner radii not greater than one-third the width of the exit with a step 

up inside the airship of not more than 29 inches and a step down outside the airship of 

not more than 36 inches; 

(ii) For an airship having a passenger seating configuration of 10 to 19 passengers, the 

emergency exit has a rectangular opening measuring not less than 20 inches wide by 36 

inches high, with corner radii not greater than one-third the width of the exit, and with a 

step up inside the airship of not more than 20 inches. The step down outside the airship

may not exceed 27 inches; and
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(iii) The airship complies with the additional requirements of HCC.561(b)(2),

HCC.803(b), HCC.811(c), HCC.812, HCC.813(b), and HCC.815.

(e) For multiengine airships, ditching emergency exits must be provided in accordance with 

the following requirements, unless the emergency exits required by paragraph (a) or (d) of this 

section already comply with them: 

(1) One exit above the waterline on each side of the airship having the dimensions 

specified in paragraph (b) or (d) of this section, as applicable; and

(2) If side exits cannot be above the waterline, there must be a readily accessible overhead 

hatch emergency exit that has a rectangular opening measuring not less than 20 inches 

wide by 36 inches long, with corner radii not greater than one-third the width of the exit. 

(3) In lieu of paragraph (e)(2) of this section, if any side exit(s) cannot be above the 

waterline, a device may be placed at each of such exit(s) prior to ditching. This device 

must slow the inflow of water when such exit(s) is opened with the airship ditched. For 

airships having a seating capacity of 19 or less excluding pilots, the clear opening of such 

exit(s) must meet the requirements defined in paragraph (d) of this section.

HCC.810 Emergency egress assist means and escape routes 

Each emergency exit must have an approved means to assist the occupants in descending to the 

ground under all probable Airship attitudes to be encountered in the moored position and in a 

minor crash landing. 

HCC.811 Emergency exit marking 

(a) Each emergency exit and external door in the passenger compartment must be externally 

marked and readily identifiable from outside the airship by—

(1) A conspicuous visual identification scheme; and

(2) A permanent decal or placard on or adjacent to the emergency exit which shows the 

means of opening the emergency exit, including any special instructions, if applicable.

(b) In addition, for airships having a seating capacity of 19 or less excluding pilots, these exits 

and doors must be internally marked with the word "exit" by a sign which has white letters 1 

inch high on a red background 2 inches high, be self-illuminated or independently, internallyelectrically illuminated, and have a minimum brightness of at least 160 microlamberts. The 

color may be reversed if the passenger compartment illumination is essentially the same.

(c) In addition, when certification to the emergency exit provisions of Sec. 23.807(d)(4) is 

requested, the following apply:

(1) Each emergency exit, its means of access, and its means of opening, must be 

conspicuously marked;

(2) The identity and location of each emergency exit must be recognizable from a distance 

equal to the width of the cabin;

(3) Means must be provided to assist occupants in locating the emergency exits in 

conditions of dense smoke;
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(4) The location of the operating handle and instructions for opening each emergency exit 

from inside the airship must be shown by marking that is readable from a distance of 30 

inches;

(5) Each passenger entry door operating handle must—

(i) Be self-illuminated with an initial brightness of at least 160 microlamberts; or

(ii) Be conspicuously located and well illuminated by the emergency lighting even in 

conditions of occupant crowding at the door;

(6) Each passenger entry door with a locking mechanism that is released by rotary motion 

of the handle must be marked—

(i) With a red arrow, with a shaft of at least three-fourths of an inch wide and a head 

twice the width of the shaft, extending along at least 70 degrees of arc at a radius 

approximately equal to three-fourths of the handle length;

(ii) So that the center line of the exit handle is within ± one inch of the projected point 

of the arrow when the handle has reached full travel and has released the locking 

mechanism; and

(iii) With the word "open" in red letters, one inch high, placed horizontally near the 

head of the arrow; and

(7) In addition to the requirements of paragraph (a) of this section, the external marking of 

each emergency exit must—

(i) Include a 2-inch colorband outlining the exit; and

(ii) Have a color contrast that is readily distinguishable from the surrounding fuselage 

surface. The contrast must be such that if the reflectance of the darker color is 15 

percent or less, the reflectance of the lighter color must be at least 45 percent. 

"Reflectance" is the ratio of the luminous flux reflected by a body to the luminous flux 

it receives. When the reflectance of the darker color is greater than 15 percent, at least a 

30 percent difference between its reflectance and the reflectance of the lighter color 

must be provided.

HCC.812 Emergency lighting 

When certification to the emergency exit provisions of HCC.807(d)(4) is requested, the 

following apply:

(a) An emergency lighting system, independent of the main cabin lighting system, must be 

installed. However, the source of general cabin illumination may be common to both the 

emergency and main lighting systems if the power supply to the emergency lighting system is 

independent of the power supply to the main lighting system.

(b) There must be a crew warning light that illuminates in the cockpit when power is on in the 

airship and the emergency lighting control device is not armed.
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(c) The emergency lights must be operable manually from the flightcrew station and be 

provided with automatic activation. The cockpit control device must have "on", "off," and 

"armed" positions so that, when armed in the cockpit, the lights will operate by automatic 

activation.

(d) There must be a means to safeguard against inadvertent operation of the cockpit control 

device from the "armed" or "on" positions.

(e) The cockpit control device must have provisions to allow the emergency lighting system 

to be armed or activated at any time that it may be needed.

(f) When armed, the emergency lighting system must activate and remain lighted when—

(1) The normal electrical power of the airship is lost; or

(2) The airship is subjected to an impact that results in a deceleration in excess of 2g and a 

velocity change in excess of 3.5 feet-per-second, acting along the longitudinal axis of the 

airship; or

(3) Any other emergency condition exists where automatic activation of the emergency 

lighting is necessary to aid with occupant evacuation.

(g) The emergency lighting system must be capable of being turned off and reset by the 

flightcrew after automatic activation.

(h) The emergency lighting system must provide internal lighting, including—

(1) Illuminated emergency exit marking and locating signs, including those required in 

HCC.811(b);

(2) Sources of general illumination in the cabin that provide an average illumination of not 

less than 0.05 foot-candle and an illumination at any point of not less than 0.01 foot-candle 

when measured along the center line of the main passenger aisle(s) and at the seat armrest 

height; and

(3) Floor proximity emergency escape path marking that provides emergency evacuation 

guidance for the airship occupants when all sources of illumination more than 4 feet above 

the cabin aisle floor are totally obscured.

(i) The energy supply to each emergency lighting unit must provide the required level of 

illumination for at least 10 minutes at the critical ambient conditions after activation of the 

emergency lighting system.

(j) If rechargeable batteries are used as the energy supply for the emergency lighting system, 

they may be recharged from the main electrical power system of the airship provided the 

charging circuit is designed to preclude inadvertent battery discharge into the charging circuit 

faults. If the emergency lighting system does not include a charging circuit, battery condition 

monitors are required.

(k) Components of the emergency lighting system, including batteries, wiring, relays, lamps, 

and switches, must be capable of normal operation after being subjected to the inertia forces 

resulting from the ultimate load factors prescribed in HCC.561(b)(2).
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(l) The emergency lighting system must be designed so that after any single transverse 

vertical separation of the gondola during a crash landing:

(1) At least 75 percent of all electrically illuminated emergency lights required by this 

section remain operative; and

(2) Each electrically illuminated exit sign required by HCC.811(b) and (c) remains 

operative, except those that are directly damaged by the gondola separation.

HCC.813 Emergency exit access 

(a) For airships having a seating capacity of 19 or less excluding pilots, access to windowtype emergency exits may not be obstructed by seats or seat backs.

(b) In addition, when certification to the emergency exit provisions of HCC.807(d)(4) is 

requested, the following emergency exit access must be provided:

(1) The passageway leading from the aisle to the passenger entry door must be 

unobstructed and at least 20 inches wide.

(2) There must be enough space next to the passenger entry door to allow assistance in 

evacuation of passengers without reducing the unobstructed width of the passageway 

below 20 inches.

(3) If it is necessary to pass through a passageway between passenger compartments to 

reach a required emergency exit from any seat in the passenger cabin, the passageway must 

be unobstructed; however, curtains may be used if they allow free entry through the 

passageway.

(4) No door may be installed in any partition between passenger compartments unless that 

door has a means to latch it in the open position. The latching means must be able to 

withstand the loads imposed upon it by the door when the door is subjected to the inertia 

loads resulting from the ultimate static load factors prescribed in HCC.561(b)(2).

(5) If it is necessary to pass through a doorway separating the passenger cabin from other 

areas to reach a required emergency exit from any passenger seat, the door must have a 

means to latch it in the open position. The latching means must be able to withstand the 

loads imposed upon it by the door when the door is subjected to the inertia loads resulting 

from the ultimate static load factors prescribed in HCC.561(b)(2).

HCC.815 Width of aisle 

The passenger aisle width at any point between seats must equal or exceed the values in the 

following table: 
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* A narrower width not less than 9 in (229 mm) may be approved when substantiated by 

appropriate tests. 

HCC.831 Ventilation 

(a) Each passenger and crew compartment must be ventilated and each crew compartment 

must have enough fresh air (but not less than 10 cubic ft (0.283 m3) per minute per crew 

member) to enable crew members to perform their duties without undue discomfort: 

(b) Air in crew and passenger compartments and all areas accessible in flight must be free 

from harmful or hazardous concentrations of gases or vapors. In meeting this requirement, the 

following apply:

(1) Carbon monoxide concentrations in excess of one part in 20,000 parts of air are 

considered hazardous. For test purposes, any acceptable carbon monoxide detection 

method may be used. 

(2) Reserved. 

(3) Helium concentrations must be established that are considered non-hazardous for 

occupants. Higher concentrations of Helium may be allowed in crew compartments and all 

areas accessible during flight if appropriate protective breathing equipment is available. 

(c) There must be provisions made to ensure that the conditions prescribed in subparagraph 

(b) of this paragraph are met after reasonably probable failures or malfunctioning of the 

ventilating, heating, or other systems and equipment. 

(d) If accumulation of hazardous quantities of smoke in the cockpit area is reasonably 

probable, smoke evacuation must be readily accomplished. 

(e) Except as provided in subparagraph (f) of this paragraph, means must be provided to 

enable the occupants of the following compartments and areas to control the temperature and 

quantity of ventilating air supplied to their compartment or area independently of the 

temperature and quantity of air supplied to other compartments and areas: 

(1) The flight-crew compartment. 
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(2) Crew-member compartments and areas other than the flight-crew compartment unless 

the crew-member compartment or area is ventilated by air interchange with other 

compartments or areas under all operating conditions. 

(f) Means to enable the flight crew to control the temperature and quantity of ventilating air 

supplied to the flight-crew compartment independently of the temperature and quantity of 

ventilating air supplied to other compartments are not required if all of the following 

conditions are met: 

(1) The total volume of the flight-crew and passenger compartments is 800 cubic ft (22.7 

m

3

) or less. 

(2) The air inlets and passages for air to flow between flight-crew and passenger 

compartments are arrange to provide compartment temperatures within 5oF (2.8°C) of each 

other and adequate ventilation to occupants in both compartments. 

(3) The temperature and ventilation controls are accessible to the flight crew. 

FIRE PROTECTION EVALUATION 

HCC.833 Combustion heating systems

Combustion heaters must be approved.

HCC.851 Fire extinguishers 

(a) Hand fire extinguishers 

(1) The following minimum number of hand fire extinguishers must be conveniently 

located and evenly distributed in passenger compartments: 

(2) At least one hand fire extinguisher must be conveniently located in the pilot 

compartment. 
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(3) At least one readily accessible hand fire extinguisher must be available for use in each 

Class A or Class B cargo or baggage compartment and in each Class E cargo or baggage 

compartment that is accessible to crew members in flight. 

(4) At least one hand fire extinguisher must be located in, or readily accessible for use in, 

each galley located above or below the passenger compartment. 

(5) Each hand fire extinguisher must be approved. 

(6) Hand fire extinguishers are required in all areas accessible in flight where fires are 

likely to occur. 

(7) The type of extinguishing agent used in the extinguishers required by this paragraph 

must be appropriate for the kinds of fires likely to occur where used. 

(8) The quantity of extinguishing agent used in each extinguisher required by this 

paragraph must be appropriate for the kinds of fires likely to occur where used. 

(9) Each extinguisher intended for use in a personnel compartment must be designed to 

minimize the hazard of toxic gas concentration.

(b) Built-in fire extinguishers: If a built-in fire extinguisher is provided: 

(1) Each built in fire extinguishing system must be installed so that: 

(i) No extinguishing agent likely to enter personnel compartments will be hazardous to 

the occupants; and 

(ii) No discharge of the extinguisher can cause structural damage. 

(2) The capacity of each required built-in fire extinguishing system must be adequate for 

any fire likely to occur in the compartment where used, considering the volume of the 

compartment and the ventilation rate. 

HCC.853 Compartment interiors 

For each compartment occupied by the crew or passengers, the following apply: 

(a) Materials (including finishes or decorative surfaces applied to the materials) must meet the 

applicable test criteria prescribed in 14 CFR part 25 Appendix F Part I, or other approved 

equivalent methods, regardless of the passenger capacity of the airship.

(b) Reserved

(c) In addition to meeting the requirements of paragraph (a) of this section, seat cushions, 

except those on flight crewmember seats, must meet the test requirements of 14 CFR part 25 

Appendix F Part II, or other equivalent methods, regardless of the passenger capacity of the 

airship.

(d) Except as provided in paragraph (e) of this section, the following interior components of 

airships with passenger capacities of 20 or more must also meet the test requirements of 14 

CFR part 25 Appendix F Parts IV and V, or other approved equivalent method, in addition to 

the flammability requirements prescribed in paragraph (a) of this section:

(1) Interior ceiling and wall panels, other than lighting lenses and windows;
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(2) Partitions, other than transparent panels needed to enhance cabin safety;

(3) Galley structure, including exposed surfaces of stowed carts and standard containers 

and the cavity walls that are exposed when a full complement of such carts or containers is 

not carried; and

(4) Large cabinets and cabin stowage compartments, other than underseat stowage 

compartments for stowing small items such as magazines and maps.

(e) The interiors of compartments, such as pilot compartments, galleys, lavatories, crew rest 

quarters, cabinets and stowage compartments, need not meet the standards of paragraph (d) of 

this section, provided the interiors of such compartments are isolated from the main passenger 

cabin by doors or equivalent means that would normally be closed during an emergency 

landing condition.

(f) Smoking is not allowed in lavatories. If smoking is allowed in any area occupied by the 

crew or passengers, an adequate number of self-contained, removable ashtrays must be 

provided in designated smoking sections for all seated occupants.

(g) Regardless of whether smoking is allowed in any other part of the airship, lavatories must 

have self-contained, removable ashtrays located conspicuously on or near the entry side of 

each lavatory door, except that one ashtray may serve more than one lavatory door if the 

ashtray can be seen readily from the cabin side of each lavatory served.

(h) Each receptacle used for the disposal of flammable waste material must be fully enclosed, 

constructed of at least fire resistant materials, and must contain fires likely to occur in it under 

normal use. The capability of the receptacle to contain those fires under all probable 

conditions of wear, misalignment, and ventilation expected in service must be demonstrated 

by test.

HCC.854 Lavatory fire protection 

For Airships with a passenger capacity of 20 or more: 

(a) Each lavatory must be equipped with a smoke detector system or equivalent that provides 

a warning light in the cockpit, or provides a warning light or audible warning in the passenger 

cabin that would be readily detected by a flight attendant; and 

(b) Each lavatory must be equipped with a built-in fire extinguisher for each disposal 

receptacle for towels, paper, or waste, located within the lavatory. The extinguisher must be 

designed to discharge automatically into each disposal receptacle upon occurrence of a fire in 

that receptacle. 

HCC.855 Cargo or baggage compartments 

For each cargo or baggage compartment not occupied by crew or passengers, the following 

apply: 

(a) The compartment must meet one of the class requirements of HCC.857. 

(b) Class B through Class C cargo or baggage compartments, as defined in HCC.857, must 

have a liner, and the liner must be separate from (but may be attached to) the Airship 

structure. 
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(c) Ceiling and sidewall liner panels of Class C compartments must meet the test requirements 

of 14 CFR part 25 Appendix F Part III or other approved equivalent methods. 

(d) All other materials used in the construction of the cargo or baggage compartment must 

meet the applicable test criteria prescribed in 14 CFR part 25 Appendix F Part I, or other 

approved equivalent methods. 

(e) No compartment may contain any controls, wiring, lines, equipment, or accessories, the 

damage or failure of which would affect safe operation, unless those items are protected so 

that: 

(1) They cannot be damaged by the movement of cargo in the compartment; and 

(2) Their breakage or failure will not create a fire hazard. 

(f) There must be means to prevent cargo or baggage from interfering with the functioning of 

the fire protective features of the compartment. 

(g) Sources of heat within the compartment must be shielded and insulated to prevent igniting 

the cargo or baggage. 

(h) Flight tests must be conducted to show compliance with the provisions of HCC.857 

concerning: 

(1) Compartment accessibility; 

(2) The entry of hazardous quantities of smoke or extinguishing agent into compartments 

occupied by the crew or passengers; and 

(3) The dissipation of the extinguishing agent in Class C compartments. 

During the above tests, it must be shown that no inadvertent operation of smoke or fire detectors 

in any compartment would occur as a result of fire contained in any other compartment, either 

during or after extinguishment, unless the extinguishing system floods each such compartment 

simultaneously. 

HCC.856 Thermal/Acoustic Insulation materials

(a) Thermal/acoustic insulation material installed in the gondola must meet the flame 

propagation test requirements of 14 CFR part 25 Appendix F part VI, or other approved 

equivalent test requirements. This requirement does not apply to "small parts," as defined in 

14 CFR part 25 Appendix F part I.

HCC.857 Cargo compartment classification 

(a) Class A: A Class A cargo or baggage compartment is one in which: 

(1) The presence of a fire would be easily discovered by a crew member while at his 

station; and 

(2) Each part of the compartment is easily accessible in flight. 

(b) Class B: A Class B cargo or baggage compartment is one in which:

(1) There is sufficient access in flight to enable a crew member to effectively reach any 

part of the compartment with the contents of a hand fire extinguisher; 
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(2) When the access provisions are being used no hazardous quantity of smoke, flames or 

extinguishing agent will enter any compartment occupied by the crew or passengers; and 

(3) There is a separate approved smoke detector or fire detector system to give warning to 

the pilot or flight engineer station. 

(c) Class C: A Class C cargo or baggage compartment is one not meeting the requirements for 

either a Class A or B compartment but in which: 

(1) There is a separate approved smoke detector or fire detector system to give warning at 

the pilot or flight engineer station; 

(2) There is an approved built-in fire extinguishing system controllable from the pilot or 

flight engineer stations;

(3) There are means to exclude hazardous quantities of smoke, flames, or extinguishing 

agent, from any compartment occupied by the crew or passengers; and 

(4) There are means to control ventilation and draughts within the compartment so that the 

extinguishing agent used can control any fire that may start within the compartment. 

HCC.858 Cargo compartment fire detection systems 

If certification with cargo compartment fire detection provisions is requested, the following must 

be met for each cargo compartment with those provisions: 

(a) The detection system must provide a visual indication to the flight crew within one minute 

after the start of a fire. 

(b) The system must be capable of detecting a fire at a temperature significantly below that at 

which the structural integrity of the Airship is substantially decreased. 

(c) There must be means to allow the crew to check in flight, the functioning of each fire 

detector circuit. 

(d) The effectiveness of the detection system must be shown for all approved operating 

configurations and conditions. 

HCC.859 Combustion heater fire protection

(a) Combustion heater fire zones: the following combustion heater fire zones must be 

protected from fire in accordance with the applicable provisions of HCC.1181 to HCC.1191 

and HCC.1195 to HCC.1203:

(1) The region surrounding the heater, if this region contains any flammable fluid system 

components (excluding the heater fuel system), that could:

(i) Be damaged by heater malfunctioning; or: 

(ii) Allow flammable fluids or vapors to reach the heater in case of leakage.

(2) The region surrounding the heater, if the heater fuel system has fittings that, if they 

leaked, would allow fuel or vapors to enter this region.

(3) The part of the ventilating air passage that surrounds the combustion chamber. 

However, no fire extinguishment is required in cabin ventilating air passages.
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(b) Ventilating air ducts: each ventilating air duct passing through any fire zone must be 

fireproof. In addition:

(1) Unless isolation is provided by fireproof valves or by equally effective means, the 

ventilating air duct downstream of each heater must be fireproof for a distance great 

enough to ensure that any fire originating in the heater can be contained in the duct; and

(2) Each part of any ventilating duct passing through any region having a flammable fluid 

system must be constructed or isolated from that system so that the malfunctioning of any 

component of that system cannot introduce flammable fluids or vapors into the ventilating 

airstream.

(c) Combustion air ducts: each combustion air duct must be fireproof for a distance great 

enough to prevent damage from backfiring or reverse flame propagation. In addition:

(1) No combustion air duct may have a common opening with the ventilating airstream 

unless flames from backfires or reverse burning cannot enter the ventilating airstream 

under any operating condition, including reverse flow or malfunctioning of the heater or its 

associated components; and

(2) No combustion air duct may restrict the prompt relief of any backfire that, if so 

restricted, could cause heater failure.

(d) Heater controls; general: provision must be made to prevent the hazardous accumulation 

of water or ice on or in any heater control component, control system tubing, or safety control.

(e) Heater safety controls: for each combustion heater there must be the following safety 

control means:

(1) Means independent of the components provided for the normal continuous control of 

air temperature, airflow, and fuel flow must be provided, for each heater, to automatically 

shut-off the ignition and fuel supply to that heater at a point remote from that heater when 

any of the following occurs:

(i) The heat exchanger temperature exceeds safe limits.

(ii) The ventilating air temperature exceeds safe limits.

(iii) The combustion airflow becomes inadequate for safe operation.

(iv) The ventilating airflow becomes inadequate for safe operation.

(2) The means of complying with subparagraph (e)(1) of this paragraph for any individual 

heater must:

(i) Be independent of components serving any other heater, the heat output of which is 

essential for safe operation; and

(ii) Keep the heater off until restarted by the crew.
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(3) There must be means to warn the crew when any heater, the heat output of which is 

essential for safe operation has been shut-off by the automatic means prescribed in 

subparagraph (e)(1) of this paragraph.

(f) Air intakes: Each combustion and ventilating air intake must be located so that no 

flammable fluids or vapors can enter the heater system under any operating condition:

(1) During normal operation; or:

(2) As a result of the malfunctioning of any other component.

(g) Heater exhaust: heater exhaust systems must meet the provisions of HCC.1121 and 

HCC.1123. In addition, there must be provisions in the design of the heater exhaust system to 

safely expel the products of combustion to prevent the occurrence of:

(1) Fuel leakage from the exhaust to surrounding compartments;

(2) Exhaust gas impingement on surrounding equipment or structure;

(3) Ignition of flammable fluids by the exhaust, if the exhaust is in a compartment 

containing flammable fluid lines; and

(4) Restriction by the exhaust of the prompt relief of backfires that, if so restricted, could 

cause heater failure.

(h) Heater fuel systems: each heater fuel system must meet each powerplant fuel system 

requirement affecting safe heater operation. Each heater fuel system component within the 

ventilating airstream must be protected by shrouds so that no leakage from those components 

can enter the ventilating airstream.

(i) Drains: there must be means to safely drain fuel that might accumulate within the 

combustion chamber or the heater exchanger. In addition:

(1) Each part of any drain that operates at high temperatures must be protected in the same 

manner as heater exhausts; and

(2) Each drain must be protected from hazardous ice accumulation under any operating 

conditions.

HCC.863 Flammable fluid fire protection 

(a) In each area where flammable fluids or vapors might escape by leakage of a fluid system, 

there must be means to minimize the probability of ignition of the fluids and vapors, and the 

resultant hazard if ignition does occur.

(b) Compliance with subparagraph (a) of this paragraph must be shown by analysis or tests, 

and the following factors must be considered: 

(1) Possible sources and paths of fluid leakage, and means of detecting leakage; 

(2) Flammability characteristics of fluids, including effects of any combustible or 

absorbing materials; 

(3) Possible ignition sources, including electrical faults, overheating of equipment, and 

malfunctioning of protective devices; 
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(4) Means available for controlling or extinguishing a fire, such as stopping flow of fluids, 

shutting down equipment, fireproof containment, or use of extinguishing agents; 

(5) Ability of Airship components that are critical to safety of flight to withstand fire and 

heat. 

(c) If action by the flight crew is required to prevent or counteract a fluid fire (e.g., equipment 

shutdown or actuation of a fire extinguisher), quick acting means must be provided to alert the 

crew. 

(d) Each area where flammable fluids or vapors might escape by leakage of a fluid system 

must be identified and defined.

HCC.865 Fire protection of flight controls, engine mounts and other flight structure 

Essential flight controls, engine mounts, and other flight structures located in designated fire 

zones or in adjacent areas which would be subjected to the effects of fire in the fire zone must be 

constructed of fireproof material or shielded so that they are capable of withstanding the effects 

of fire. 

HCC.869 Fire protection: systems 

(a) Electrical system components: 

(1) Components of the electrical system must meet the applicable fire and smoke 

protection requirements of HCC.831 (b) and 863.

(2) Electrical cables, terminals, and equipment in designated fire zones that are used during 

emergency procedures, must be at least fire resistant.

(3) Main power cables (including generator cables) must be designed with flexibility in the 

routing to minimize the amount of deformation and stretching to prevent failure and must 

be: 

(i) Isolated from flammable fluid lines; or 

(ii) Shrouded by means of electrically insulated, flexible conduit, or equivalent, which 

is in addition to the normal cable insulation. 

(4) Insulation on electrical wire and electrical cable installed in any area of the Airship 

must be self-extinguishing when tested in accordance with the applicable portions of 14 

CFR part 25 Appendix F Part I(a)(3). 

(b) Each vacuum air system line and fitting on the discharge side of the pump that might 

contain flammable vapors or fluids must meet the requirements of HCC.1183 if the line or 

fitting is in a designated fire zone. Other vacuum air systems components in designated fire 

zones must be at least fire resistant.

MISCELLANEOUS 

HCC.871 Leveling means

There must be means for determining when the Airship is in a level position on the ground. 
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HCC.875 Protection near propellers 

(a) Design precautions must be taken to avoid damage to the Airship by the effect of vibration 

induced by passing propeller tips and to minimize the hazards to the Airship in the event of 

ice thrown from unducted propellers. The hazards which must be considered include damage 

to structure and critical systems.

(b) For vectored thrusters every possible inclination must be considered under (a). 

(c) No window may be near the propeller tips unless it can withstand the most severe ice 

impact likely to occur. 

AIRSHIP SPECIFICS 

HCC.883 Non-rigid Airship envelope 

For the envelope of non-rigid Airships the following shall apply: 

(a) The envelope must be designed to be pressurized and maintain sufficient superpressure 

(amount of envelope pressure in excess of ambient pressure) to remain in tension while 

supporting the limit design loads for all flight conditions and ground conditions, except for 

mooring and handling conditions, where wrinkling at the ends of the nose battens is permitted 

under loads larger than limit but should not occur to a level were damage to the envelope can 

happen. The effects of all local aerodynamic pressures (including thrust slipstream 

impingement) and pitch angles must be included in the determination of stresses to arrive at 

the limit-strength requirements for the envelope fabric. In determining limit design loads of 

the envelope the most critical areas with maximum envelope pressure-, aerodynamic-, 

structure- and suspension system loads must be considered if applicable.

(b) The envelope fabric must have an ultimate strength not less than 4 times the limit load 

determined by the maximum design internal pressure combined with the maximum load 

resulting from any of the requirements specified herein and taking into account the effects of 

environmental conditions such as temperature and humidity, expected in service. 

(c) Suspension system components made of fabric or non-metallic material must have an 

ultimate strength of not less than four times the prescribed limit loads. A minimum pitch 

angle of ±30° must be used in determining system suspension loads. 

(d) It must be demonstrated by test in accordance with the section Tearing Strength of the 

Appendix B that the envelope fabric (in both the warp and woof (fill) directions) can 

withstand limit design loads without further tearing. 

(e) Reserved

(f) Ballonets must be designed and installed such that their center of gravity of their combined 

volume will coincide longitudinally, within approved limits determined in HCC.27, with the 

center of buoyancy of the envelope. The ballonet system must be designed so that the static 

trim capabilities of the system about the center of buoyancy of the Airship are equally divided 

between the fore and aft ballonets, if provided. The effective trim capabilities of the ballonets 

must be maintained approximately equal between the limits of 0 to 100% ballonet fullness. 

Sufficient means must be provided to prevent trapping of air when partially deflated. 
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(g) Unless it is demonstrated that breaking away when the airship is parked or moored is 

extremely improbable, provisions must be installed to permit rapid envelope deflation should 

the Airship break away during parking or mooring. If the Airship is to be left unattended, 

automatic deflation must be provided. The system must be protected against inadvertent use 

and must be properly identified and available to crew members.

(h) A means must be provided to permit emergency deflation of the envelope on the ground 

during emergency evacuation of the occupants. Normal valving of lifting gas may be 

considered in meeting this requirement. 

(i) Internal and/or external suspension systems for supporting components and connecting 

them to the envelope, such as a keel, crew and passenger compartments and propulsion units, 

must be designed to transmit and distribute the resulting loads to the envelope in a uniform 

manner for all flight conditions. Fabric parts of such systems and their connection to the 

envelope must be designed and constructed such that the bonds are not subjected to peeling 

loads. Provisions must be made to prevent chafing between suspension system components 

and air system components. 

(j) The nose of the envelope must be designed to prevent wrinkling due to high speed flight. 

(k) Gas tight sleeves must be provided at locations where suspension cables penetrate the 

envelope. These must be of sufficient length to allow for envelope stretch and other 

dimensional changes and uncertainties. If suspension system cables must be adjustable to 

ensure proper load distribution throughout the service life of the Airship, the adjustable part 

must be located on the air side of the suspension system. 

(l) The envelope and ballonets must be protected from chafing with the suspension system 

cables and/or other solid elements. 

(m) Fire hazard to the envelope have to be investigated and must be minimized; and:

(1) it has to be demonstrated that the gas filled envelope has self-extinguishing capabilities; 

helium as a lifting gas along with a flash resistant material meets this criteria; or;

(2) the envelope material have self-extinguishing properties according to 14 CFR part 25, 

Appendix F Part I (a)(v).

(n) Acceptable envelope leakage rates and purity degradation values have to be established 

and published in the Airship Flight Manual.

(o) Reserved

(p) The envelope shall be protected from: 

(1) heat emanating from engines, heaters and the sun; 

(2) off-limit air pressures within the Airship cover; 

(3) ice thrown by propeller or debris. 

HCC.887 Lifting gas pressure system 

(a) Non-rigid Airships: 
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(1) A means shall be provided to control the internal pressure of the envelope and to 

provide air to the ballonets and must contain at least the following components: 

(i) Lifting gas Valves: at least two valves must be provided. The valves may be located 

either on or near the envelope but not higher than 10° above the equator. They must be 

designed for both manual and automatic operation, be operable at specified pressure 

settings at all attainable air speeds, and be designed to open and close positively and be 

prevented from sticking and/or freezing. The valves must not discharge lifting gas into 

spaces normally accessible to occupants, the engine intake system, or the ballonets. The 

valves must be of sufficient capacity to permit ascent above pressure height at the 

maximum design rate-of-climb but not less than 3000 ft/min (15 m/s) without exceeding 

lifting gas pressure of 1.25 times maximum operating pressure. 

(ii) Air Valve(s): at least one air valve must be provided to discharge air from each 

ballonet. The valves may be located in the envelope or connected to it by a suitable 

duct. The valve(s) must be capable of manual and automatic operation and be capable 

of operating at appropriate pressure settings at all attainable air speeds and must be 

designed to open and close positively and be prevented from sticking and/or freezing. 

The valve(s) must be of sufficient capacity to permit ascent below pressure height at the 

maximum design rate-of-climb without exceeding lifting gas pressure of 1.15 times 

maximum operating pressure. It must not be possible for the pilot to manually and 

simultaneously to lock all air valves closed to prevent envelope overpressure in the 

climb and a resultant automatic release of helium. If the Airship has only one valve per 

ballonet, then a system must be provided to prevent both fore and aft ballonet valves 

from being manually locked closed simultaneously. If the Airship has multiple valves 

per ballonet, then it must not be possible to manually lock one particular valve closed. 

This would normally be valve #1, the highest pressure valve, in the forward ballonet. 

(iii) Ballonet Air Induction System: scoops, ducts, blowers and dampers (air inlet 

valves) or combinations of these must be of sufficient capacity to permit descent at the 

maximum design rate but not less than 1500 ft/min (7.5 m/sec) with sufficient pressure 

to maintain envelope shape and control system functions. The effects of single or 

multiple engine failure if the system is dependent on engine functioning must be 

determined. 

(iv) Air supply source: A reliable means of supplying air to the ballonet, must be 

provided, and must have adequate capacity to enable the pressure in the envelope to be 

maintained during flight at low engine powers and forward speeds, and, if appropriate, 

when thrust vectoring reduces the effectiveness of the engines in supplying air. The 

means shall also be able to maintain envelope shape to permit operation of systems 

dependent upon that shape following the failure of all engines for a sufficient time to 

permit a landing to be made. 

(2) Provisions must be made to blow air into the lifting gas space to supplement the 

ballonet in case of excessive lifting gas loss. The control(s) for this system must be readily 

accessible and quickly operable by the crew. A lifting gas pressure sufficient to prevent 
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wrinkling of the envelope at a forward speed of 0.25 VH must be maintained with a descent 

rate of 300 ft/min (1.5 m/s). 

(b) Reserved

(c) Controls and instruments necessary for controlled release or transfer of lifting gas by the 

crew must be provided. Such controls and instruments shall be located and arranged so that 

they may be operated by the crew in the correct manner without undue concentration or 

fatigue. If remotely actuated lifting gas valves are used, a mechanical backup system must be 

provided. 

HCC.889 Ground handling provisions 

Provisions for ground handling must be provided as required by HCC.255. All fabric patches and 

fittings of ground handling lines must be designed with a breaking strength of not less than 1.15 

the specified breaking strength of the attached cable or line assembly strength. 

HCC.891 Flutter 

The envelope and all fixed and movable control surfaces must be shown to be free from flutter, 

up to VH plus Um, VCD or VMO whichever is greater, by analysis supported by flight test. 

HCC.893 Lifting gas 

The lifting gas must be non-flammable, non-toxic and non-irritant. The acceptable lifting gas 

and purity requirements upon inflation shall be specified as part of the airship design.

HCC.897 External load means of attachment 

For Airships carrying external loads or ballast the following apply: 

(a) The external load must not interfere with the Airship's ability to maintain safe flight and to 

be controllable during takeoff, landing, taxiing, parking and the load exchange process. 

(b) The mechanism for handling external loads must be designed for the maximum predicted 

inertia factors. 

(c) Loads must be applied to the load support structure in the directions and angles produced 

by pitch and roll of the Airship during all flight phases while carrying an external load. 

Angles of ±30° pitch and ± 20° roll are required by the Administrator as minimum values. 

(d) It must be shown by analysis or test or both that the load cannot be unintentionally 

released during flight.

HCC.898 Jettisonable external loads

(a) The external load attaching means, for jettisonable airship-load combinations, must 

include a quick-release system to enable the pilot to release the external load quickly during 

flight. The quick-release system must consist of a primary quick release subsystem and a 

backup quick release subsystem that are isolated from one another. The quick release system, 

and the means by which it is controlled, must comply with the following:

(1) A control for the primary quick release subsystem must be installed either on one of the 

pilot's primary controls or in an equivalently accessible location and must be designed and 

located so that it may be operated by either the pilot or a crewmember without hazardously 

limiting the ability to control the airship during an emergency situation.
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(2) A control for the backup quick release subsystem, readily accessible to either the pilot 

or another crewmember, must be provided.

(3) Both the primary and backup quick release subsystems must—

(i) Be reliable, durable, and function properly with all external loads up to and including 

the maximum external limit load for which authorization is requested.

(ii) Be protected against electromagnetic interference (EMI) from external and internal 

sources and against lightning to prevent inadvertent load release.

(A) The minimum level of protection required for jettisonable rotorcraft-load 

combinations used for nonhuman external cargo is a radio frequency field strength of 

20 volts per meter.

(iii) Be protected against any failure that could be induced by a failure mode of any 

other electrical or mechanical airship system.

(b) The critically configured jettisonable external loads must be shown by a combination of 

analysis, ground tests, and flight tests to be both transportable and releasable throughout the 

approved operational envelope without hazard to the airship during normal flight conditions. 

In addition, these external loads-must be shown to be releasable without hazard to the airship 

during emergency flight conditions.

(c) A placard or marking must be installed next to the external-load attaching means clearly 

stating any operational limitations and the maximum authorized external load as demonstrated 

under HCC.25 and this section.

(d) The fatigue evaluation of HCC.571 of this part does not apply to airship-load 

combinations to be used for nonhuman external cargo except for the failure of critical 

structural elements that would result in a hazard to the airship. 

HCC.899 Hoists and suspended loads 

(a) It must be shown by analysis and test that the hoisting/sling load system is designed for 

static limit loads derived from the maximum suspended masses, for which authorization is 

sought, multiplied by a factor of 2. The load is applied in the vertical direction and in any 

direction making an angle of 30° relative to the vertical. 

(b) It must be shown by analysis and test that any Airship mooring provisions and their 

supports used to hold a light airship in place during connection of external loads are designed 

for static limit static loads induced by the loading and unloading operation multiplied by a 

load factor of 3. 

(c) It must be shown by analysis and simulation, supported by test that oscillations of masses 

suspended from the hovering Airship will be manageable and will not damage the Airship.

(d) It must be shown by analysis supported by test that - during the cargo transfer - the kinetic 

energy of the suspended mass due to oscillations in combination with the dynamics of the 

hovering Airship and the lowering speed of the cargo hoist does not endanger the Airship's 

controllability.
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(e) Ropes, cables and/or other devices attached to the lowered suspended mass for 

longitudinal and lateral adjustment of the precise settling and positioning of the mass must be 

designed to absorb all inertial forces due to the dynamics addressed in (c). The rope, wire and 

cable factors in HCC.628 apply. 

(f) For the hoisting/sling load system, including all cables, winches, control equipment and 

ancillary components, proof must be furnished of the suitability, durability and reliability of 

the entire device. HCC.1309 applies. 
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Subpart E - Powerplant (Thrusters)

GENERAL 

HCC.901 Installation 

(a) For the purpose of this code, Airship powerplant installations include each component 

that: 

(1) Is necessary for propulsion in any direction; 

(2) Affects the safety and control of the major propulsion unit(s); or: 

(3) Affects the safety of the major propulsive units between normal inspections or 

overhauls. 

(b) For each powerplant: 

(1) The installation must comply with: 

(i) The installation instructions provided under 14 CFR part 33.5 (engine), and 14 CFR 

part 35.3 (propeller) or equivalent instructions; and: 

(ii) The applicable provisions of this Subpart. 

(2) The components of the installation must be constructed, arranged, and installed so as to 

ensure their continued safe operation between normal inspections or overhauls. 

(3) The installation must be accessible for necessary inspections and maintenance; and 

(4) The major components of the installation must be electrically bonded to the other parts 

of the Airship. 

(c) The powerplant installation must comply with HCC.1309. 

(d) Reserved

(e) The satisfactory functioning of the power unit must be demonstrated by ground and flight 

tests over the range of operating conditions for which certification is required and must 

include tests under hot climatic conditions, unless equivalent evidence can be produced. 

HCC.903 Engines 

(a) Engine type certification: 

(1) Each engine must be approved and have a type certificate. Alternately, the engine(s) 

may be certificated as part of the airship to the provisions of 14 CFR part 33.

(2) Each turbine engine not certificated to 14 CFR part 33 must be shown to comply with 

14 CFR part 33 or be shown to have a foreign object ingestion service history in similar 

installation locations which has not resulted in any unsafe condition or that the particular 

installation excludes ingestion. 

(b) Engine isolation: The powerplants must be arranged and isolated from each other to allow 

operation, in at least one configuration, so that the failure or malfunction of any engine, or the 

failure or malfunction (including destruction by fire in the engine compartment) of any system 
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that can affect an engine (other than a fuel tank, if only one fuel tank for two engines is 

installed), will not: 

(1) Prevent the continued safe operation of the remaining engines; or 

(2) Require immediate action by a crew member for continued safe operation of the 

remaining engines. 

(c) Control of engine rotation: There must be a means for stopping the rotation of any engine 

individually in flight, except that means for stopping the rotation of any engine need to be 

provided only where continued rotation could jeopardize the safety of the Airship:

(1) In particular, where no means are provided to prevent continued rotation, the safety of 

the Airship must be shown in the event of failure of the engine oil supply. (See 14 CFR 

part 33 for turbine engines)

(2) Each component of the stopping system on the engine side of the firewall that might be 

exposed to fire must be at least fire resistant. 

(3) If hydraulic propeller feathering systems are used for this purpose, the feathering lines 

must be at least fire-resistant under the operating conditions that may be expected to exist 

during feathering. 

(d) Turbine engine installations: For turbine engine installations 

(1) Design precautions must be taken to minimize the hazards to the Airship in the event of 

an engine-rotor failure or a fire originating inside the engine which burns through the 

engine casing;

(2) The powerplant systems associated with engine control devices, systems, and 

instrumentation must be designed to give reasonable assurance that those operating 

limitations that adversely affect turbine rotor structural integrity will not be exceeded in 

service. 

(e) Restart capability. 

(1) Means to restart any engine in flight must be provided. 

(2) An altitude and airspeed envelope must be established for the Airship for in-flight 

engine restarting, and each installed engine must have a restart capability within that 

envelope. 

(f) Starting and stopping (piston engine): the design of the installation must be such that risk 

of fire or mechanical damage to the engine or Airship, as a result of starting is reduced to a 

minimum. Any techniques and associated limitations for engine starting must be established 

and published in the Airship Flight Manual, approved manual material, or applicable 

operating placards. Means must be provided for stopping and restarting each engine in flight. 

In addition the following apply: 

(1) Each component of the stopping system on the engine side of the firewall that might be 

exposed to fire must be at least fire resistant; 
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(2) If hydraulic propeller feathering systems are used for this purpose, the feathering lines 

must be at least fire resistant under the operating conditions that may be expected to exist 

during feathering. 

HCC.905 Propellers 

(a) Each propeller must be approved and have a type certificate. Alternately, the propeller(s) 

may be certificated as part of the airship to the provisions of 14 CFR part 35.

(b) Engine power and propeller shaft rotational speed must not exceed the limits for which the 

propeller is certificated or approved for (See 14 CFR part 35). 

(c) Each component of the propeller blade pitch control system must meet the requirements of 

14 CFR part 35. 

(d) Design precautions must be taken to minimize the hazards to the Airship and occupants in 

the event a propeller blade fails or is released by a hub failure. The hazards which must be 

considered include damage to structure, gas cells, load carrying parts of envelope, suspensions 

and catenary (if installed) and critical systems due to impact of a failed or released blade and 

the unbalance created by such failure or release. 

(e) If a vectoring system is installed the combination of swiveling speed, airspeed, and engine 

power may not exceed the limits for which the propeller is designed for. 

HCC.907 Vibration 

(a) Propeller vibration: (See 14 CFR part 35) 

(b) Engine vibration: each engine must be installed to prevent the harmful vibration of any 

part of the engine or Airship. 

(c) Thrust vectoring: the thruster drive system and vectored operation of the thruster may not 

subject the propeller/gearbox and/or the principal rotating parts of the engine to excessive 

vibration stresses. This must be shown by a vibration investigation. 

(d) For diesel engines a flutter or vibration analysis shall be done that includes:

(1) the whirl mode degree of freedom which takes into account the stability of the plane of 

rotation of the propeller and significant elastic, inertial, and aerodynamic forces, and 

(2) propeller, engine, engine mount and structural stiffness and damping variations 

appropriate to the particular configuration, and 

(3) the flutter or vibration investigation will include showing the engine – attachment –

airship structure is free from flutter with one cylinder inoperative.

(e) Considering the vibration characteristics of diesel engines, the applicant must comply with 

the following:

(1) Each diesel engine installation must be constructed and arrange to result in vibration 

characteristics that—

(i) Do not exceed those established during the type certification of the engine; and
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(ii) Do not exceed vibration characteristics that a previously certificated airframe 

structure has been approved for –

(A) Unless such vibration characteristics are showing to have no effect on safety or 

continued airworthiness, or

(B) Unless mitigated to an acceptable level by utilization of isolators, dampers, 

clutches, and similar provisions, so that unacceptable vibration levels are not 

imposed on the previously certificated structure.

HCC.908 Cooling fans

For cooling fans that are a part of a powerplant installation the following apply: 

(a) For cooling fans installed in Airships, it must be shown that a fan blade failure will not 

prevent continued safe flight either because of damage caused by the failed blade or loss of 

cooling air. 

(b) Fatigue evaluation: Unless a fatigue evaluation under HCC.571 is conducted, it must be 

shown that cooling fan blades are not operating at resonant conditions within the operating 

limits of the Airship. 

HCC.909 Turbochargers 

(a) Each turbocharger must be approved under the engine type certificate. 

(b) Control system malfunctions, vibrations, and abnormal speeds and temperatures expected 

in service may not damage the turbocharger compressor or turbine. 

(c) Each turbocharger case must be able to contain fragments of a compressor or turbine that 

fails at the highest speed that is obtainable with normal speed control devices inoperative. 

(d) Each intercooler installation, where provided, must comply with the following. 

(1) The mounting provisions of the intercooler must be designed to withstand the loads 

imposed on the system; 

(2) It must be shown that, under the installed vibration environment, the intercooler will 

not fail in a manner allowing portions of the intercooler to be ingested by the engine; 

(3) Airflow through the intercooler must not discharge directly on any Airship component 

(e.g. windshield) unless such discharge is shown to cause no hazard to the Airship under 

all operating conditions. 

(e) Engine power, cooling characteristics, operating limits, and procedures affected by the 

turbocharger system installations must be evaluated. Turbocharger operating procedures and 

limitations must be published in the Airship Flight Manual in accordance with HCC.1581. 

HCC.917 Thruster drive system 

(a) General: the thruster drive system includes any part necessary to transmit power from the 

engines to the thruster or propeller. This includes gearboxes, shafting, universal joints, 

couplings, thruster brake assemblies, clutches, supporting bearings for shafting, any attendant 

accessory pads or drives, and any cooling fans that are a part of, attached to, or mounted on 

the thruster drive system. Paragraphs HCC.918 to HCC.924 will also apply.
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HCC.918 Shafting critical speed 

(a) The critical speeds of any shafting must be determined by demonstration except that 

analytical methods may be used if reliable methods of analysis are available for the particular 

design. 

(b) If any critical speed lies within, or close to, the operating ranges for idling, power-on, and 

autorotative conditions, the stresses occurring at that speed must be within safe limits. This 

must be shown by tests.

(c) If analytical methods are used and show that no critical speed lies within the permissible 

operating ranges, the margins between the calculated critical speeds and the limits of the 

allowable operating ranges must be adequate to allow for possible variations between the 

computed and actual values. 

HCC.919 Shafting joints 

Each universal joint, slip joint and other shafting joints which require lubrication for operation 

must have provision for lubrication.

HCC.921 Thruster brake 

If there is a means to control the rotation of the thruster drive system independently of the 

engine, any limitations on the use of that means must be specified, and the control for that means 

must be guarded to prevent inadvertent operation. 

HCC.923 Thruster drive system and control mechanism tests 

(a) Endurance tests, general: each thruster drive system and thruster control mechanism must 

be tested, as prescribed in subparagraphs (b) to (j) and (m) of this paragraph, for at least 50 

hours. These tests must be conducted as follows: 

(1) Five-hour test cycles must be used. 

(2) The tests must be conducted on the Airship or may be conducted on a representative 

bench test facility. The load, the frequency, and the methods of application to the affected 

thruster drive system components must be representative of Airship conditions. Test 

components must be those used for showing compliance with the remainder of this 

paragraph. 

(3) The test torque and rotational speed must be: 

(i) determined by the powerplant limitations; and 

(ii) absorbed by the thruster to be approved for the Airship. 

(b) Endurance tests, maximum thrust run: the maximum thrust run must be conducted as 

follows: 

The maximum thrust torque run must consist of 0.5 hour of alternate runs of 5 minutes at 

maximum thrust torque and the maximum speed for use with maximum thrust torque, and 5 

minutes at as low an engine idle speed as practicable. The engine must be declutched from the 

thruster drive system, and the thruster brake, if furnished and so intended, must be applied 

during the first minute of the idle run. During the remaining 4 minutes of the idle run, the 
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clutch must be engaged so that the engine drives the thruster at the minimum practical rpm. 

Acceleration of the engine and the thruster drive system must be done at the maximum rate. 

When declutching the engine, it must be decelerated rapidly enough to allow the operation of 

the overrunning clutch. 

(c) Endurance tests, maximum continuous vector thrust: 1.5 hours of continuous operation at 

maximum continuous torque and the maximum speed for use with maximum continuous 

torque must be conducted. 

The main thruster controls must be operated at a minimum of 15 times each hour through the 

main thruster pitch positions of maximum thrust and minimum thrust, except that the control 

movements need not produce loads or blade flapping motion exceeding the maximum loads of 

motions encountered in flight. 

(d) Endurance tests: 90% of maximum continuous run: 1 hour of continuous operation at 90% 

of maximum continuous torque and the maximum speed for use with 90% of maximum 

continuous torque must be conducted. 

(e) Endurance tests: 80% of maximum continuous run: 1 hour of continuous operation at 80% 

of maximum continuous torque and the minimum speed for use with 80% of maximum 

continuous torque must be conducted. 

(f) Endurance tests: 60% of maximum continuous run: 1 hour of continuous operation at 60% 

of maximum continuous torque and the minimum speed for use with 60% of maximum 

continuous torque must be conducted. 

(g) Endurance tests: engine malfunctioning run: It must be determined whether 

malfunctioning of components, such as the engine fuel or ignition systems, or whether 

unequal engine power can cause dynamic conditions detrimental to the drive system. If so, a 

suitable number of hours of operation must be accomplished under those conditions. 

(h) Endurance tests: overspeed run: One hour of continuous operation must be conducted at 

maximum continuous torque and the maximum power-on overspeed expected in service, 

assuming that speed and torque limiting devices, if any, function properly. 

(i) Endurance tests, clutch and brake engagements:

A total of at least 100 clutch and brake engagements, including the engagements of 

subparagraph (b) of this paragraph, must be made during the take-off torque runs and, if 

necessary, at each change of torque and speed throughout the test. The clutch engagements 

must be accomplished at the speed and by the method prescribed for the product.

(j) Any components that are affected by maneuvering and gust loads must be investigated for 

the same flight conditions as are the thrusters, and their service lives must be determined by 

fatigue tests or by other acceptable methods. In addition, a level of safety equal to that of the 

thrusters must be provided for each component in the thruster drive system, the failure of 

which would cause an uncontrolled hover or landing.

(k) Each part tested as prescribed in this paragraph must be in a serviceable condition at the 

end of the tests. No intervening disassembly which might affect test results may be conducted. 
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(l) Endurance tests; operating lubricants: To be approved for use in thruster drive and control 

systems, lubricants must meet the specifications of lubricants used during the tests prescribed 

by this paragraph. Additional or alternate lubricants may be qualified by equivalent testing or 

by comparative analysis of lubricant specifications and thruster drive and control system 

characteristics. In addition: 

(1) At least one 10-hour cycle required by this paragraph must be conducted with 

transmission and gearbox lubricant temperatures, at the location prescribed for 

measurement, not lower than the maximum operating temperature for which approval is 

requested; 

(2) For pressure lubricated systems, at least one 10-hour cycles required by this paragraph 

must be conducted with the lubricant pressure, at the location prescribed for measurement, 

not higher than the minimum operating pressure for which approval is requested. 

(m) The manufacturer may propose an alternate endurance test procedure if the thruster 

system differs in character from that in this part. This test plan must be approved by the 

Administrator.

HCC.924 Additional tests 

(a) Any additional dynamic, endurance, and operational tests, and vibratory investigations 

necessary to determine that the thruster drive mechanism is safe, must be performed. 

(b) Lubrication system failure. For lubrication systems required for proper operation of 

thruster drive systems, it must be shown that the thruster drive system is capable of operating 

under 75% of max. continuous power conditions for at least 15 minutes.

(c) The tests prescribed in subparagraphs (a) and (b) of this paragraph must be conducted on 

the Airship and the torque must be absorbed by the thrusters to be installed, except that other 

ground or flight test facilities with other appropriate methods of torque absorption may be 

used if the conditions of support and vibration closely simulate the conditions that would exist 

during a test on the Airship. 

HCC.925 Propeller clearance 

(a) Ground clearance: 

Propellers and shrouds must have positive ground clearance under most adverse conditions 

expected under normal operation. 

(b) Structural clearance: There must be: 

(1) sufficient clearance between the propeller blades or cuffs and stationary parts of the 

Airship, including radial clearance to prevent harmful vibration; 

(2) positive clearance between other rotating parts of the propeller or spinner and 

stationary parts of the Airship; 

(3) sufficient clearance between the propeller and the Airship envelope so as to minimize 

damage from debris or ice thrown by the propellers unless propeller shrouds or equivalent 

protective means are provided.
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(4) positive clearance between propellers and shrouds under all flight and ground 

conditions specified in these criteria. 

(c) Hazards from propeller and shroud interference for minor crash landings must be 

considered in the design for each propeller vectoring position. 

(d) Ducted propellers: 

(1) (a) and (c) apply.

HCC.929 Propeller de-icing 

(a) Propeller and other complete engine installations must be protected against the 

accumulation of ice as necessary to enable satisfactory functioning without appreciable loss of 

power when operated in the icing conditions for which certification is requested. 

(b) If combustible fluid is used for propeller de-icing, HCC.1181 to 1185 and HCC.1189 

apply. 

HCC.933 Reversing systems 

(a) Reserved

(b) Reversing systems must be designed so that no unsafe condition will result during normal 

operation of the system, or from any failure (or reasonably likely combination of failures) of 

the reversing system, under any anticipated condition of operation of the Airship including 

ground operation. Failure of structural elements need not be considered if the probability of 

this kind of failure is extremely remote. 

HCC.937 Turbopropeller - drag limiting systems

Turbopropeller-powered Airship propeller-drag limiting systems must be designed so that no 

single failure or malfunction of any of the systems during normal or emergency operation results 

in propeller drag in excess of that for which the Airship was designed under HCC.367. Failure of 

structural elements of the drag limiting systems need not be considered if the probability of this 

kind of failure is extremely remote.

HCC.939 Powerplant operating characteristics 

(a) Turbine engine powerplant operating characteristics must be investigated in flight to 

determine that no adverse characteristics (such as stall, surge, or flameout) are present, to a 

hazardous degree, during normal and emergency operation within the range of operating 

limitations of the Airship and of the engine.

(b) Turbocharged reciprocating engine operating characteristics must be investigated in flight 

to assure that no adverse characteristics, as a result of an inadvertent overboost, surge, 

flooding, or vapor lock, are present during normal or emergency operation of the engine(s) 

throughout the range of operating limitations of both Airship and engine.

(c) For turbine engines, the air inlet system must not, as a result of airflow distortion during 

normal operation, cause vibration harmful to the engine.

(d) It must be established over the range of operating conditions for which certification is 

required that the powerplant installation does not induce engine carcass vibration in excess of 

the acceptable levels established during engine type certification under 14 CFR part 33.83 (e). 
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(e) For governor-controlled engines, it must be shown that there exists no hazardous torsional 

instability of the drive system associated with critical combinations of power, rotational 

speed, and control displacement. 

HCC.943 Negative acceleration 

No hazardous malfunction of an engine or any component or system associated with the 

powerplant unit may occur when the Airship is operated at the negative accelerations within the 

flight envelopes prescribed in HCC.333. This must be shown for the greatest duration expected 

for the acceleration. 

HCC.945 Powerplant Installation – One cylinder inoperative

Tests or analysis, or a combination of methods, must show that the airframe can withstand the 

shaking or vibratory forces imposed by the engine if a cylinder becomes inoperative. 

Appropriate design considerations or operating procedures, or both, shall be developed to 

prevent airframe and propeller damage.

HCC.947 Powerplant Installation – High Energy Engine Fragments

It may be possible for diesel engine cylinders (or portions thereof) to fail and physically separate 

from the engine at high velocity (due to the high internal pressures). This failure mode will be 

considered possible in engine designs with removable cylinders or other non-integral block 

designs. The following is required:

(a) It must be shown that the engine construction type (massive or integral block with nonremovable cylinders) is inherently resistant to liberating high energy fragments in the event of 

a catastrophic engine failure; or,

(b) It must be shown by the design of the engine, that engine cylinders, other engine 

components or portions thereof (fragments) cannot be shed or blown off of the engine in the 

event of a catastrophic engine failure; or 

(c) It must be shown that all possible liberated engine parts or components do not have 

adequate energy to penetrate engine cowlings; or

(d) Assuming infinite fragment energy, and analyzing the trajectory of the probable fragments 

and components, any hazard due to liberated engine parts or components will be minimized 

and the possibility of crew injury is eliminated. Minimization must be considered during 

initial design and not presented as an analysis after design completion.

FUEL SYSTEM 

HCC.951 General 

(a) Each fuel system must be constructed and arranged to ensure a flow of fuel at a rate and 

pressure established for proper engine functioning under each likely operating condition, 

including any maneuver for which certification is requested. 

(b) Each fuel system must be arranged so that 

(1) No fuel pump can draw fuel from more than one tank at a time; or 

(2) There are means to prevent introducing air into the system. 
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(c) Each fuel system for a turbine or diesel engine must be capable of sustained operation 

throughout its flow and pressure range with fuel initially saturated with water at 80°F (27°C) 

and having 0.2 cm3of free water per liter added and cooled to the most critical condition for 

icing likely to be encountered in operation.

(d) Each fuel system for a turbine engine powered Airship must meet the applicable fuel 

venting requirements of 14 CFR part 34. 

HCC.952 Fuel system analysis and test 

(a) Proper fuel system functioning under all probable operating conditions must be shown by 

analysis and those tests found necessary by the Administrator. Tests, if required, must be 

made using the Airship fuel system or a test article that reproduces the operating 

characteristics of the portion of the fuel system to be tested. 

(b) The likely failure of any heat exchanger using fuel as one of its fluids may not result in a 

hazardous condition. 

(c) Each fuel heat exchanger must be able to withstand without failure any vibration, inertia 

and fuel pressure load to which it may be subjected in operation. 

HCC.953 Fuel system independence 

Each fuel system must meet the requirements of HCC.903 (b) by:

(a) Allowing the supply of fuel to each engine through a system independent of each part of 

the system supplying fuel to any other engine; or 

(b) Any other acceptable method. 

HCC.954 Fuel System lightning protection 

The fuel system must be designed and arranged to prevent the ignition of fuel vapor within the 

system by:

(a) direct lightning strikes to areas having a high probability of stroke attachment; 

(b) swept lightning strokes on areas where swept strokes are highly probable; 

(c) corona or streamering at fuel vent outlets. 

HCC.955 Fuel Flow 

(a) Each fuel system must provide at least 100% of the fuel flow required under each intended 

operating condition and maneuver. Compliance must be shown as follows: 

(1) Fuel must be delivered to each engine at a pressure, corrected for accelerations (load 

factors), within the limits specified in the engine type certificate. 

(2) The quantity of fuel in the tank may not exceed the amount established as the unusable 

fuel quantity for that tank under the requirements of HCC.959 plus that necessary to show 

compliance with this paragraph. 

(3) Each main pump must be used that is necessary for each operating condition and 

attitude for which compliance with this paragraph is shown, and the appropriate emergency 

pump must be substituted for each main pump so used. 
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(4) If there is a fuel flowmeter, it must be blocked and the fuel must flow through the meter 

or its bypass. 

(5) The fuel head between the tank and the engine must be critical with respect to Airship 

flight attitudes. 

(b) If an engine can be supplied with fuel from more than one tank, the fuel system must for 

each engine, in addition to having appropriate manual switching capability, be designed to 

prevent interruption of fuel flow to that engine, without attention by the flight crew, when any 

tank supplying fuel to that engine is depleted of usable fuel during normal operation, and any 

other tank, that normally supplies fuel to that engine alone, contains usable fuel. 

HCC.957 Flow between interconnected tanks 

(a) Where tank outlets are interconnected and allow fuel to flow between them due to gravity 

or flight accelerations, it must be impossible for fuel to flow between tanks in quantities great 

enough to cause overflow from the tank vent in any sustained flight condition. 

(b) If fuel can be pumped from one tank to another in flight: 

(1) The design of the vents and the fuel transfer system must prevent structural damage to 

tanks from overfilling; and 

(2) There must be means to warn the crew before overflow through the vents occurs. 

HCC.959 Unusable fuel supply 

The unusable fuel supply for each fuel tank and its fuel system components must be established 

as not less than that quantity at which the first evidence of engine malfunctioning occurs under 

the most adverse fuel-feed condition occurring under each intended operation and flight 

maneuver involving fuel feeding from that tank. Fuel system component failures need not be 

considered. 

HCC.961 Fuel system hot weather operation 

(a) The fuel system must perform satisfactorily in hot weather operation. This must be shown 

by demonstrating that the fuel system from the tank outlets to each engine is pressurized, 

under all intended operations, so as to prevent vapor formation, or must be shown by climbing 

from the altitude of the airport elected for the product to the maximum altitude established as 

an operating limitation under HCC.1527. If a climb test is elected, there must be no evidence 

of vapor lock or other malfunctioning during the climb test conducted under the following 

conditions:

(1) For piston engine powered Airships, the power settings should be maintained at the 

maximum approved levels for takeoff and climb to provide for the maximum fuel flow. 

The climb should be continued to the maximum operating altitude approved for the 

Airship. If a lower altitude is substantiated, appropriate limitations should be published in 

the Airship Flight Manual. 

(2) For turbine engine powered Airships, the engines must operate at takeoff power/ 

maximum thrust for the time interval selected for showing the takeoff flight path, and at 

maximum continuous power for the rest of the climb. 
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(3) The mass of the Airship must be with full fuel tanks, minimum crew, and the ballast 

necessary to maintain the center of gravity within allowable limits or other combinations 

approved by the Administrator. 

(4) The climb airspeed may not exceed the maximum airspeed established for climbing 

from takeoff to the maximum operating altitude. 

(5) The fuel temperature must be at least 110oF (43°C). 

(b) The test prescribed in subparagraph (a) of this paragraph may be performed in flight or on 

the ground under closely simulated flight conditions. If a flight test is performed in weather 

cold enough to interfere with the proper conduct of the test, the fuel tank surfaces, fuel lines, 

and other fuel system parts subject to cold air must be insulated to simulate, insofar as 

practicable, flight in hot weather. 

HCC.963 Fuel tanks: general 

(a) Each fuel tank must be able to withstand, without failure, the vibration, inertia, fluid, and 

structural loads that it may be subjected to in operation. 

(b) Flexible fuel tank liners must be approved or must be shown to be suitable for the 

particular application. 

(c) Each integral fuel tank must have adequate facilities for interior inspection and repair. 

(d) Fuel tanks shall be designed, located and installed so that no fuel is released in or near the 

Airship or near the engines in quantities sufficient to start a serious fire in otherwise 

survivable crash conditions.

(e) Fuel tanks within the Airship must be able to resist rupture, and to retain fuel, under the 

inertia forces prescribed for the emergency landing conditions in HCC.561. In addition, these 

tanks must be in a protected position so that exposure of the tanks to scraping action with the 

ground is unlikely. 

(f) For pressurized fuel tanks, a means with failsafe features must be provided to prevent the 

build-up of an excessive pressure difference between the inside and the outside of the tank.

(g) Fuel tank access covers must comply with the following criteria in order to avoid loss of 

hazardous quantities of fuel: All covers located in an area where experience or analysis 

indicates a strike is likely, must be shown by analysis or tests to minimize penetration and 

deformation by low energy engine debris, or other likely debris.

HCC.965 Fuel tank tests 

(a) It must be shown by tests that the fuel tanks mounted in the Airship can withstand, without 

failure or leakage, the more critical of the pressures resulting from the conditions specified in 

subparagraphs (a)(1) and (2) of this paragraph. In addition it must be shown by either analysis 

or tests, that tank surfaces subjected to more critical pressures resulting from the conditions of 

subparagraphs (a)(3) and (4) of this paragraph, are able to withstand the following pressures: 

(1) An internal pressure of 3.5 psi (24.14 kPa). 

(2) 125% of the maximum air pressure developed in the tank from ram effect. 
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(3) Fluid pressures developed during maximum limit accelerations, and deflections, of the 

Airship with a full tank. 

(4) Fluid pressures developed during the most adverse combination of Airship pitch, yaw 

and roll and fuel load. 

(b) Each metallic tank with large unsupported or unstiffened flat surfaces, the failure or 

deformation of which, could cause fuel leakage, must be able to withstand the following test, 

or its equivalent, without leakage or excessive deformation of the tank walls: 

(1) Each complete tank assembly and its supports must be vibration tested while mounted 

to simulate the actual installation. 

(2) Except as specified in subparagraph (b)(4) of this paragraph, the tank assembly must be 

vibrated for 25 hours at an amplitude of not less than 0.03125 in (0.8 mm) (unless another 

amplitude is substantiated) while two-thirds filled with water or other suitable test fluid. 

(3) The test frequency of vibration must be as follows: 

(i) If no frequency of vibration resulting from any rpm within the normal operating 

range of engine speeds is critical, the test frequency of vibration must be 2000 cycles 

per minute. 

(ii) If only one frequency of vibration resulting from any rpm within the normal 

operating range of engine speeds is critical, that frequency of vibration must be the test 

frequency. 

(iii) If more than one frequency of vibration resulting from any rpm within the normal 

operating range of engine speeds is critical, the most critical of these frequencies must 

be the test frequency. 

(4) Under subparagraph (b)(3) (ii) and (iii) of this paragraph, the time of test must be 

adjusted to accomplish the same number of vibration cycles that would be accomplished in 

25 hours at the frequency specified in subparagraph (b)(3)(i) of this paragraph. 

(5) During the test, the tank assembly must be rocked at the rate of 16 to 20 complete 

cycles per minute, through an angle of 15o on both sides of the horizontal (30o total), about 

the most critical axis, for 25 hours. If motion about more than one axis is likely to be

critical, the tank must be rocked about each critical axis for 12.5 hours. 

(c) Except where satisfactory operating experience with a similar tank in a similar installation 

is shown, non-metallic tanks must withstand the test specified in subparagraph (b)(5) of this 

paragraph, with fuel at a temperature of 110oF (43°C). During this test, a representative 

specimen of the tank must be installed in a supporting structure simulating the installation in 

the Airship. 

(d) For pressurized fuel tanks, it must be shown by analysis or tests that the fuel tanks can 

withstand the maximum pressure likely to occur on the ground or in flight taking the 

additional pressures of (a)(3) and (a)(4) of this subparagraph into account.
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HCC.967 Fuel tank installation 

(a) Each fuel tank must be supported so that tank loads are not concentrated. In addition: 

(1) There must be pads, if necessary, to prevent chafing between each tank and its 

supports; 

(2) Padding must be non-absorbent, or treated to prevent the absorption of fuel; 

(3) If a flexible tank liner is used, it must be supported so that it is not required to 

withstand fluid loads; 

(4) Interior surfaces adjacent to the liner must be smooth and free from projections that 

could cause wear of the liner, unless 

(i) Provisions are made for protection of the liner at those points, or 

(ii) The liner construction itself provides such protection; 

(5) A positive pressure must be maintained within the vapor space of each bladder cell 

under all conditions of operation except for particular condition for which it is shown that a 

zero or negative pressure will not cause the bladder cell to collapse;

(6) Siphoning of fuel (other than minor spillage) or collapse of bladder fuel cells must be 

possible as a result of being improperly secured or the loss of the fuel filler cap. 

(b) Each tank compartment must be ventilated and drained to prevent the accumulation of 

flammable fluids or vapors. Each compartment adjacent to a tank that is an integral part of the 

Airship structure must also be ventilated and drained. If the tank is in a sealed compartment, 

ventilation may be limited to drain holes large enough to prevent excessive pressure resulting 

from altitude changes.

(c) The location of each tank must meet the requirements of HCC.1185(a). 

(d) No engine nacelle skin immediately behind a major air outlet from the engine 

compartment may act as the wall of an integral tank. 

(e) Each fuel tank must be isolated from personnel compartments by a fume proof and fuel 

proof enclosure.

(f) Fuel tanks must be designed, located (as practicable away from occupants compartments) 

and installed so as to retain fuel under the inertia forces prescribed for the emergency landing 

conditions in HCC.561. 

HCC.969 Fuel tank expansion space 

Each fuel tank must have an expansion space of not less than 2% of the tank capacity. It must be 

impossible to fill the expansion space inadvertently with the Airship in the normal ground 

attitude. For pressure fueling systems, compliance with this paragraph may be shown with the

means provided to comply with HCC.979(b).

HCC.971 Fuel tank sump 

(a) Each fuel tank must have a sump which is able to be drained properly in the normal 

ground attitude or with the Airship moored, parked, or in flight, if requested, and with an 
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effective capacity, under these conditions, of not less than 0.10% of the tank capacity unless 

operating limitations are established to ensure that the accumulation of water in service will 

not exceed the sump capacity. 

(b) The capacity prescribed in subparagraph (a) of this paragraph must be effective with the 

Airship in the normal ground attitude or moored, parked, or in flight, if requested, and the 

sump must be located so that the sump contents cannot escape through the tank outlet 

opening. Each fuel tank must allow drainage of any hazardous quantity of water from any part 

of the tank to its sump with the Airship in the normal ground attitude or moored, parked, or in 

flight, if requested. 

(c) Each fuel tank sump must have a drain which is accessible with the Airship on the ground 

or moored, parked or in flight, if requested, that: 

(1) Allows complete drainage of the sump on the ground; 

(2) Discharges clear of each part of the Airship; and 

(3) Has manual or automatic means for positive locking in the closed position. 

HCC.973 Fuel tank filler connection 

(a) Each fuel tank filler connection must be marked as prescribed in HCC.1557(c). 

(b) Spilled fuel must be prevented from entering the fuel tank compartment or any part of the 

Airship other than the tank itself. 

(c) Each filler cap must provide a fuel-tight seal for the main filler opening. 

(d) Each fuel-filling point must have a provision for electrically bonding the Airship to 

ground fueling equipment.

(e) Each recessed filler connection that can retain any appreciable quantity of fuel must have a 

drain that discharges clear of each part of the Airship. 

(f) Filler caps must be designed to minimize the probability of incorrect installation or in 

flight loss.

(g) For Airships with engines requiring gasoline as the only permissible fuel, the inside 

diameter of the fuel filler opening must be no larger than 2.36 inch (59.9 mm).

(h) For Airships with turbine or Diesel engines, the inside diameter of the fuel filler opening 

must be no smaller than 2.95 inch (74.9 mm). 

HCC.975 Fuel tank vents and carburetor vapor vents

(a) Each fuel tank must be vented from the top part of the expansion space so that venting is 

effective under any normal flight condition. In addition: 

(1) Each vent outlet must be located and constructed in a manner that minimizes the 

possibility of being obstructed by ice or other foreign matter;

(2) Each vent must be constructed to prevent siphoning of fuel during normal operation; 

(3) The venting capacity and vent pressure levels must maintain acceptable differences of 

pressure between the interior and exterior of the tank, during: 
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(i) Normal flight operation; 

(ii) Maximum rate of ascent and descent; and 

(iii) Refueling and defueling (where applicable);

(4) Airspaces of tanks with interconnected outlets must be interconnected; 

(5) There may be no undrainable points in any vent line where moisture can accumulate 

with the Airship in either the ground or level flight attitudes;

(6) No vent or drainage provision may terminate at a point where the discharge of fuel 

from the vent outlet will constitute a fire hazard or from which fumes could enter crew and 

passenger compartments.

(b) Each carburetor with vapor elimination connections and each fuel injection engine 

employing vapor return provisions must have a separate vent line to lead vapors back to the 

top of a fuel tank. If there is more than one fuel tank, and it is necessary to use these tanks in a 

definite sequence for any reason, the vapor vent return line must lead back to the fuel tank to 

be used first, unless the relative capacities of the tanks are such that return to another tank is 

preferable.

HCC.977 Fuel tank outlet 

(a) There must be a fuel strainer for the fuel tank outlet or for the booster pump. This strainer 

must 

(1) For gasoline powered reciprocating engine-powered Airships, have 8 to 16 meshes per 

inch (3 to 6 meshes per cm); 

(2) For diesel and turbine engine-powered Airships, prevent the passage of any object that 

could restrict fuel flow or damage any fuel-system component.

(b) The clear area of each fuel tank outlet strainer must be at least five times the area of the 

outlet line. 

(c) The diameter of each strainer must be at least that of the fuel tank outlet. 

(d) Each finger strainer must be accessible for inspection and cleaning. 

HCC.979 Pressure fueling system

For pressure fueling systems, the following apply.

(a) Each pressure fueling system fuel manifold connection must have means to prevent the 

escape of hazardous quantities of fuel from the system if the fuel entry valve fails.

(b) An automatic shutoff means must be provided to prevent the quantity of fuel in each tank 

from exceeding the maximum quantity approved for that tank. This means must: 

(1) allow checking for proper shutoff operation before each fueling of the tank, and

(2) Provide indication, at each fueling station, of failure of the shut-off means to stop the 

fuel flow at the maximum quantity approved for that tank.
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(c) A means must be provided to prevent damage to the fuel system in the event of failure of 

the automatic shutoff means prescribed in subparagraph (b) of this paragraph. 

(d) The Airship pressure fueling system (not including fuel tanks and fuel tank vents) must 

withstand an ultimate load that is 2.0 times the load arising from the maximum pressures, 

including surge, that is likely to occur during fueling. The maximum surge pressure must be 

established with any combination of tank valves being either intentionally or inadvertently 

closed.

(e) The Airship defueling system (not including fuel tanks and fuel tank vents) must withstand 

an ultimate load that is 2.0 times the load arising from the maximum permissible defueling 

pressure (positive or negative) at the Airship fueling connection.

HCC.981 Fuel tank ignition prevention 

(a) No ignition source may be present at each point of the fuel tank or fuel tank system where 

catastrophic failure could occur due to ignition of fuel or vapors. This must be shown by:

(1) Determining the highest temperature allowing a safe margin below the lowest expected 

auto-ignition temperature of the fuel in the fuel tanks. 

(2) Demonstrating that no temperature at each place inside each fuel tank where fuel 

ignition is possible will exceed the temperature determined under sub-paragraph (a)(1) of 

this paragraph. This must be verified under all probable operating, failure and malfunction 

conditions of each component, the operation, failure or malfunction of which could 

increase the temperature inside the tank. 

(b) Based on the evaluations required by this paragraph, critical design configuration control 

limitations, inspections or other procedures must be established as necessary to prevent 

development of ignition sources within the fuel tank system and must be included in the 

Airworthiness Limitations Section of the ICA required by HCC.1529. Placards, decals or 

other visible means must be placed in areas of the Airship where maintenance, repairs or 

alterations may violate the critical design configuration limitations. 

(c) The fuel tank installation must include: 

(1) Means to minimize the development of flammable vapors in the fuel tanks; or

(2) Means to mitigate the effects of an ignition of fuel vapors within fuel tanks such that no 

damage caused by an ignition will prevent continued safe flight and landing.

HCC.983 Fuel Tanks Temperature Limits

If the fuel in the tanks cannot be shown to flow suitably under all possible temperature 

conditions (fuel tank external surface heaters are acceptable mitigation), then fuel temperature 

limitations are required. These limitations will be considered as part of the essential operating 

parameters for the aircraft and must be limitations. Limitations will be determined as follows:

(a) The takeoff temperature limitation must be determined by testing or analysis to define the 

minimum fuel cold-soaked temperature of the fuel that the airship can operate on.

(b) The minimum operating temperature limitation must be determined by testing to define 

the minimum acceptable operating temperature acceptable after takeoff (with minimum 

takeoff temperature established in (a) above).
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FUEL SYSTEM COMPONENTS 

HCC.991 Fuel pumps 

(a) Main pumps: each fuel pump required for proper engine operation, or required to meet the 

fuel system requirements of this Subpart (other than those in subparagraph (b) of this 

paragraph), is a main pump. For each main pump, provision must be made to allow the bypass 

of each positive displacement fuel pump approved as part of the engine. 

(b) Emergency pumps: there must be emergency pumps or another main pump to feed each 

engine immediately after failure of any main pump. 

(c) Warning means: If both the normal pump and emergency pump operate continuously, 

there must be a means to indicate to the appropriate flight crewmember a malfunction of 

either pump. 

(d) Operation of any fuel pump may not affect engine operation so as to create a hazard, 

regardless of the engine power or thrust setting or functional status of any other fuel pump. 

HCC.993 Fuel system lines and fittings 

(a) Each fuel line must be installed and supported to prevent excessive vibration and to 

withstand loads due to fuel pressure and accelerated flight conditions. 

(b) Each fuel line connected to components of the Airship between which relative motion 

could exist must have provisions for flexibility. 

(c) Each flexible connection in fuel lines that may be under pressure and subjected to axial 

loading must use flexible hose assemblies. 

(d) Each flexible hose must be approved or must be shown to be suitable for the particular 

application. 

(e) No flexible hose that might be adversely affected by exposure to high temperatures may be 

used where excessive temperatures will exist during operation or after engine shutdown. 

(f) Each fuel line must be designed and installed to allow a reasonable degree of deformation 

and stretching without leakage. 

HCC.994 Fuel system components 

Fuel system components must be protected from damage which could result in spillage of 

enough fuel to constitute a fire hazard as a result of a ACLS retracted landing. 

HCC.995 Fuel valves 

There must be a means to allow appropriate flight crew members rapidly to shut off the fuel to 

each engine individually in flight. In addition to the requirements of HCC.1189 for shut-off 

means, each fuel valve must: 

(a) Reserved

(b) be supported so that no loads resulting from their operation or from accelerated flight 

conditions are transmitted to the lines attached to the valve. 
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HCC.997 Fuel strainer or filter 

(This paragraph does not apply to fuel strainers or filters already approved as part of an engine 

type certificated under 14 CFR part 33.) 

There must be a fuel strainer or filter between the fuel tank outlet and the inlet of either the fuel 

metering device or an engine-driven positive displacement pump, whichever is nearer the fuel 

tank outlet. This fuel strainer or filter must 

(a) Be accessible for draining and cleaning and must incorporate as screen or element which is 

easily removable; 

(b) Have a sediment trap and drain except that it need not have a drain if the strainer or filter 

is easily removable for drain purposes; 

(c) Be mounted so that its weight is not supported by the connecting lines or by the inlet or 

outlet connections of the strainer or filter itself; 

(d) Have the capacity (with respect to operating limitations established for the engine) and the 

mesh to ensure that engine fuel system functioning is not impaired, with the fuel contaminated 

to a degree (with respect to particle size and density) that is greater than that established for 

the engine in 14 CFR part 33, or equivalent regulations. 

(e) In addition, unless means are provided in the fuel system to prevent the accumulation of 

ice on the filter, a means must be provided to automatically maintain the fuel flow if ice 

clogging of the filter occurs. 

HCC.999 Fuel system drains 

(a) Drainage of the fuel system must be accomplished by the use of fuel strainer and fuel tank 

sump drains 

(b) Each drain required by subparagraph (a) of this paragraph and HCC.971 must 

(1) discharge clear of all parts of the Airship; 

(2) Have manual or automatic means for positive locking in the closed position; 

(3) Have a drain valve that is readily accessible and which can be easily opened and 

closed. 

HCC.1001 Fuel jettisoning system

If a fuel jettisoning system is installed, the following applies: 

(a) Fuel jettisoning systems are only for emergency use.

(b) Fuel jettisoning must be safe during all flight regimes for which jettisoning is to be 

authorized. 

(c) In showing compliance with subparagraph (a) of this paragraph, it must be shown that:

(1) the fuel jettisoning system and its operation are free from fire hazard; 

(2) the fuel discharges clear of any part of the Airship; 

(3) fuel or fumes do not enter any part of the Airship; 

(4) the jettisoning operation does not adversely affect the controllability of the Airship. 
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(d) The fuel jettisoning valve must be designed to allow the crew (minimum crew) to safely 

interrupt fuel jettisoning and to close the valve during any part of the jettisoning operation. 

(e) Unless it is shown that using any means and any engine operation (including engine 

vectoring or operation of auxiliary power units) does not adversely affect fuel jettisoning, 

there must be a placard, adjacent to the jettisoning control, to warn crew members against 

jettisoning during operations that adversely affect fuel jettisoning. 

(f) The fuel jettisoning system must be designed so that any reasonably probable single 

malfunction in the system will not result in a hazardous condition due to the inability to 

jettison fuel. 

OIL SYSTEM 

HCC.1011 General 

(a) Each engine must have an independent oil system that can supply it with an appropriate 

quantity of oil at a temperature not above that safe for continuous operation. 

(b) The usable oil tank capacity may not be less than the product of the endurance of the 

Airship under critical operating conditions and the maximum oil consumption of the engine 

under the same conditions, plus a suitable margin to ensure adequate circulation and cooling. 

(c) For an oil system without an oil transfer system, only the usable oil tank capacity may be 

considered. The amount of oil in the engine oil lines, the oil radiator, and the feathering 

reserve, may not be considered. 

(d) If an oil transfer system is used, the amount of oil in the transfer lines that can be pumped 

by the transfer pump must be included in the oil capacity. 

HCC.1013 Oil tanks 

(This paragraph does not apply to oil tanks already approved as part of an engine type 

certificated under 14 CFR part 33.) 

(a) Installation: each oil tank must be installed to: 

(1) meet the requirements of HCC.967; 

(2) withstand any vibration, inertia, and fluid loads expected in operation. 

(b) Expansion space: oil tank expansion space must be provided so that 

(1) Each oil tank used with a reciprocating engine has an expansion space of not less than 

the greater of 10% of the tank capacity or 0.5 US-gallons (1.9 liter), and each oil tank used 

with a turbine engine has an expansion space of not less than 10% of the tank capacity;

(2) It is impossible to fill the expansion space inadvertently with the Airship in the normal 

ground attitude. 

(3) Each reserve oil tank not directly connected to any engine may have an expansion 

space of not less than 2% of the tank capacity. 

(c) Filler connection: each recessed oil tank filler connection that can retain any appreciable 

quantity of oil must have a drain that discharges clear of each part of the Airship. In addition: 

(1) Each oil tank filler cap must provide an oil tight seal; 
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(2) Each oil tank filler must be marked as prescribed in HCC.1557(c). 

(d) Vent: oil tanks must be vented as follows: 

(1) Each oil tank must be vented from the top part of the expansion space so that the vent 

connection is not covered by oil under any normal flight condition; 

(2) Oil tank vents must be arranged so that condensed water vapor that might freeze and 

obstruct the line cannot accumulate at any point.

(e) Outlet: no oil tank outlet may be enclosed by any screen or guard that would reduce the 

flow of oil below a safe value at any operating temperature. No oil tank outlet diameter may 

be less than the diameter of the engine oil pump inlet. Each oil tank used with a turbine engine 

must have means to prevent entrance into the tank itself, or into the tank outlet, of any object 

that might obstruct the flow of oil through the system. There must be a shutoff valve at the 

outlet of each oil tank used with a turbine engine, unless the external portion of the oil system 

(including of tank supports) is fireproof. 

(f) Flexible liners: each flexible oil tank liner must be approved or must be shown to be 

suitable for the particular application. 

(g) Each filler cap of an oil tank that is used with a turbine engine must provide an oil tight 

seal. 

HCC.1015 Oil tank tests 

(This paragraph does not apply to oil tanks already approved as part of an engine type 

certificated under 14 CFR part 33.) 

Each oil tank must be designed and installed so that: 

(a) It can withstand, without failure, each vibration, inertia, and fluid load that it may be 

subjected to in operation; and

(b) It meets the provisions of HCC.965, except: 

(1) The test pressure: 

(i) For pressurized tanks used with a turbine engine, may not be less than 34.45 kPa (5 

psi) plus the maximum operating pressure of the tank instead of the pressure specified 

in HCC.965(a); and

(ii) For all other tanks, may not be less than 5 psi (34.45 kPa) instead of the pressure 

specified in HCC.965(a); and 

(2) The test fluid must be oil at 250oF (120°C) instead of the fluid specified in HCC.965(c). 

HCC.1017 Oil lines and fittings 

(a) Oil lines: oil lines must meet HCC.993, and each oil line and fitting in any designated fire 

zone must meet the requirements of HCC.1183. Oil lines must accommodate a flow of oil at a 

rate and pressure adequate for proper engine functioning under any normal operating 

condition. 

(b) Breather lines: breather lines must be arranged so that 
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(1) condensed water vapor or oil that might freeze and obstruct the line cannot accumulate 

at any point;

(2) the breather discharge will not constitute a fire hazard if foaming occurs, or cause 

emitted oil to strike the pilot's windshield; 

(3) the breather does not discharge into the engine air-induction system; 

(4) the breather outlet its protected against blockage by ice or foreign matter. 

HCC.1019 Oil strainer or filter 

(This paragraph does not apply to oil strainers or filters already approved as part of an engine 

type certificated under 14 CFR part 33.) 

(a) Each turbine engine installation must incorporate an oil strainer or filter through which all 

of the engine oil flows and which meets the following requirements. 

(1) Each oil strainer or filter that has a bypass must be constructed and installed so that oil 

will flow at the normal rate through the rest of the system with the strainer or filter 

completely blocked. 

(2) The oil strainer or filter must have the capacity (with respect to operating limitations 

established for the engine) and the mesh to ensure that engine oil system functioning is not 

impaired when the oil is contaminated to a degree (with respect to particle size and 

density) that is greater than that established for the engine in 14 CFR part 33 or equivalent 

regulations. 

(3) The oil strainer or filter, unless it is installed at an oil tank outlet, must incorporate an 

indicator that will indicate contamination of the screen before it reaches the capacity 

established in accordance with subparagraph (2) of this paragraph. 

(4) The bypass of a strainer or filter must be constructed and installed so that the release of 

collected contaminants is minimized by appropriate location of the bypass to ensure that 

collected contaminants are not in the bypass flow path.

(5) An oil strainer or filter that has no bypass, except on that installed at an oil tank outlet, 

must have a means to connect it to the warning system required in subparagraph 

1305(c)(7). 

(b) Each oil strainer or filter in a powerplant installation using reciprocating engines must be 

constructed and installed so that oil will flow at the normal rate through the rest of the system 

with the strainer or filter element completely blocked. 

HCC.1021 Oil system drains 

A drain (or drains) must be provided to allow safe drainage of the oil system. Each drain must: 

(a) Be accessible; and 

(b) Have manual or automatic means for positive locking in the closed position. 

HCC.1023 Oil radiators 

If installed: 
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(a) each oil radiator and its supporting structures must be able to withstand the vibration, 

inertia, and oil pressure loads to which it would be subjected in operation. 

(b) each oil radiator air duct must be located so that, in case of fire, flames coming from 

normal openings of the engine nacelle cannot impinge directly upon the radiator. 

HCC.1025 Oil valves 

(a) Each oil shut-off must meet the requirements of HCC.1189. 

(b) The closing of oil shut-off means may not prevent propeller feathering. 

(c) Each oil valve must have positive stops or suitable index provisions in the 'on' and 'off ' 

positions and must be supported so that no loads resulting from its operation or from 

accelerated flight conditions are transmitted to the lines attached to the valve. 

HCC.1027 Propeller feathering system 

(a) If the propeller feathering system depends on engine oil, there must be means to trap an 

amount of oil in the tank if the supply becomes depleted due to failure of any part of the 

lubricating system, other than the tank itself. 

(b) The amount of trapped oil must be enough to accomplish feathering and must be available 

only to the feathering pump. 

(c) The ability of the system to accomplish feathering with the trapped oil must be shown. 

This may be done on the ground using an auxiliary source of oil for lubricating the engine 

during operation. 

(d) Provisions must be made to prevent sludge or other foreign matter from affecting the safe 

operation of the propeller feathering system. 

COOLING 

HCC.1041 General 

The powerplant cooling provisions must be able to maintain the temperatures of powerplant

components and engine fluids, within the temperature limits established during ground and flight 

operations to the maximum altitude for which approval is requested and after normal engine 

shutdown. 

HCC.1043 Cooling tests 

(a) General: compliance with HCC.1041 must be shown under critical ground and flight 

operating conditions (including loiter, hover, climb, and descent) to the maximum altitude for 

which approval is requested. For turbocharged engines, each turbocharger must be operated 

through that part of the climb profile for which operation with the turbocharger is requested 

and in a manner consistent with its intended operation. For these tests, the following apply. 

(1) If the tests are conducted under conditions deviating from the maximum ambient 

atmospheric temperature specified in subparagraph (b), of this paragraph, the recorded 

powerplant temperature must be corrected under paragraphs (c) and (d) of this paragraph, 

unless a more rational correction method is applicable. 
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(2) No corrected temperature determined under subparagraph (1) of this paragraph may 

exceed established limits. 

(3) The fuel used during the cooling tests must be of the minimum grade approved for the 

engines, and for reciprocating engines the mixture settings must be the leanest

recommended for flight. 

(b) Maximum ambient atmospheric temperature: a maximum ambient atmospheric 

temperature corresponding to sea level conditions of at least 100°F (38°C) must be 

established. The assumed temperature lapse rate is 3.6°F (2°C) per thousand feet of altitude 

above sea level. However, for winterization installations, a maximum ambient atmospheric 

temperature corresponding to sea level conditions of less than 100°F (38°C) may be selected 

for the product. 

(c) Correction factor (except cylinder barrels): Unless a more rational correction applies, 

temperatures of engine fluids and powerplant components (except cylinder barrels) for which 

temperature limits are established, must be corrected by adding to them the difference 

between the maximum ambient atmospheric temperature and the temperature of the ambient 

air at the time of the first occurrence of the maximum component or fluid temperature 

recorded during the cooling test. 

(d) Correction factor for cylinder barrel temperatures: Cylinder barrel temperatures must be 

corrected by adding to them 0.7 times the difference between the maximum ambient 

atmospheric temperature and the temperature of the ambient air at the time of the first 

occurrence of the maximum cylinder barrel temperature recorded during the cooling test. 

HCC.1045 Cooling test procedures 

(a) General: Compliance with HCC.1041 must be shown for the takeoff, climb, en-route, and 

landing stages of flight that correspond to the applicable performance requirements. For each 

stage of flight, the cooling test must be conducted with the Airship 

(1) In the configuration most critical for cooling (including cowl flap settings selected for 

the product for reciprocating engine powered Airships, if applicable, and where vectored 

thrust is provided, including vectoring procedures established for the product); 

(2) Under the operational conditions most critical for cooling. 

(b) Temperature stabilization: For the purpose of the cooling tests, a temperature is 'stabilized' 

when its rate of change is less than 2°F (1.1°C) per minute. The following stabilization rules 

apply for each stage of flight:

(1) The temperatures must be stabilized under the conditions from which entry is made 

into the stage of flight being investigated; or

(2) If the entry condition normally does not allow temperatures to stabilize, operation 

through the full entry condition must be conducted before entry into the stage of flight 

being investigated in order to allow the temperatures to have attained their natural levels at 

the time of entry.

(c) Duration of test: For each stage of flight the test must be continued until 

(1) The component and engine-fluid temperatures stabilize; or
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(2) The stage of flight is completed; or 

(3) An operating limitation is reached. 

(d) Turbine engine powered Airships: The following additional requirement applies: The takeoff cooling test must be preceded by a period during which the powerplant component and 

engine-fluid temperatures are stabilized with the engines at ground idle.

(e) For reciprocating engine-powered Airships, engine-cooling tests during climb must be 

conducted as follows: 

(1) The most critical engine is inoperative; 

(2) Engine temperature must be stabilized in level flight with the engine at not less than 

75% of maximum continuous power.

(3) The climb must begin at the lowest practicable altitude with the engine at takeoff power 

for the specified duration of takeoff power and then with maximum continuous power. 

(4) The climb must be conducted at a speed not more than the best rate of climb speed with 

maximum continuous power unless the slope of the flight path at the speed chosen for the 

cooling test is equal to or greater than the minimum required angle of climb determined 

under HCC.65 and the Airship has a cylinder head temperature indicator. 

(5) The climb must be continued at maximum continuous power for at least 5 minutes after 

the occurrence of the highest temperature recorded (or pressure height). 

(f) The hovering cooling provisions must be shown: 

(1) For vectoring procedures established for the product. 

(2) With the vector thrust controls operated through the (pitch) positions of maximum and 

minimum horizontal thrust. 

(3) With maximum continuous power or a power which corresponds with (2) and 

maximum heaviness for this configuration, until at least 5 minutes after the occurrence of 

the highest temperature recorded. 

LIQUID COOLING 

HCC.1061 Installation 

(a) General: Each liquid-cooled engine must have an independent cooling system (including 

coolant tank) installed so that: 

(1) Each coolant tank is supported so that tank loads are distributed over a large part of the 

tank surface; 

(2) There are pads or other isolation means between the tank and its supports to prevent 

chafing; and 

(3) Pads or any other isolation means that is used must be non-absorbent or must be treated 

to prevent absorption of flammable fluids; and 

(4) No air or vapor can be trapped in any part of the system, except the coolant tank

expansion space, during filling or during operation.
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(b) Coolant tank: The tank capacity must be at least 1 US-gallon (3.8 liters), plus 10% of the 

cooling system capacity. In addition:

(1) Each coolant tank must be able to withstand the vibration, inertia and fluid loads to 

which it may be subjected in operation; 

(2) Each coolant tank must have an expansion space of at least 10% of the total cooling 

system capacity; and 

(3) It must be impossible to fill the expansion space inadvertently with the Airship in the 

normal ground attitude. 

(c) Filler connection: Each coolant tank filler connection must be marked as specified in 

HCC.1557 In addition: 

(1) Spilled coolant must be prevented from entering the coolant tank compartment or any 

part of the Airship other than the tank itself; and 

(2) Each recessed coolant filler connection must have a drain that discharges clear of the 

entire Airship. 

(d) Lines and fittings: Each coolant system line and fitting must meet the requirements of 

HCC.993, except that the inside diameter of the engine coolant inlet and outlet lines may not 

be less than the diameter of the corresponding engine inlet and outlet connections. 

(e) Radiators: Each coolant radiator must be able to withstand any vibration, inertia and 

coolant pressure load to which it may normally be subjected. In addition: 

(1) Each radiator must be supported to allow expansion due to operating temperatures and 

prevent the transmittal of harmful vibration to the radiator; and 

(2) If flammable coolant is used, the air intake duct to the coolant radiator must be located 

so that (in case of fire) flames from the nacelle cannot strike the radiator. 

(f) Drains: There must be an accessible drain that: 

(1) Drains the entire cooling system (including the coolant tank, radiator and the engine) 

when the Airship is in the normal ground attitude; 

(2) Discharges clear of the entire Airship; and 

(3) Has means to lock it closed positively. 

HCC.1063 Coolant tank tests 

Each coolant tank must be tested under HCC.965, except that: 

(a) The test required by HCC.965 (a) (1) must be replaced with a similar test using the sum of 

the pressure developed during the maximum ultimate acceleration with a full tank or a 

pressure of 3.5 psi (24.12 kPa), whichever is greater, plus the maximum working pressure of 

the system; and: 

(b) For a tank with a non-metallic liner the test fluid must be coolant rather than fuel as 

specified in HCC.965 (c) and the slosh test on a specimen liner must be conducted with the 

coolant at operating temperature. 
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INDUCTION SYSTEM 

HCC.1091 Air intake 

(a) The air intake system for each engine must supply: 

(1) The air required by that engine under the operating conditions for which certification is 

requested, and: 

(2) The air for proper fuel metering and mixture distribution with the air intake system 

valves in any position. 

(b) Each reciprocating engine installation must have at least two separate air intake sources 

and must meet the following. 

(1) Primary air intakes may open within the cowling if that part of the cowling is isolated 

from the engine accessory section by a fire-resistant diaphragm or if there are means to 

prevent the emergence of backfire flames. 

(2) Each alternate air intake must be located in a sheltered position and may not open 

within the cowling if the emergence of backfire flames will result in a hazard. 

(3) The supplying of air to the engine through the alternate air intake system may not result 

in a loss of excessive power in addition to the power loss due to the rise in air temperature. 

(4) Each automatic alternate air door must have an override means accessible to the flight 

crew. 

(5) Each automatic alternate air door must have a means to indicate to the flight crew when 

it is not closed 

(c) For air intakes for turbine engine-powered installations the following apply: 

(1) Air intakes may not open within the cowling, unless that part of the cowling is isolated 

from the engine accessory section by means of a fireproof diaphragm; 

(2) There must be means to prevent hazardous quantities of fuel leakage or overflow from 

drains, vents, or other components of flammable fluid systems from entering the engine 

intake system; 

(3) The air inlet ducts must be located or protected so as to minimize the ingestion of 

foreign matter during take-off, landing, parking, mooring and taxiing;

(4) If the engine air intake system contains parts or components that could be damaged by 

foreign objects entering the air intake, it must be shown by tests or, if appropriate, by 

analysis that the air intake system design can withstand the foreign object ingestion test 

conditions of 14 CFR part 33 without failure of parts or components that could create a 

hazard. 

HCC.1093 Air intake system de-icing and anti-icing provisions 

(a) Reciprocating engines: Each reciprocating engine air-induction system must have means 

to prevent and eliminate icing. Unless this is done by other means, it must be shown that, in 

air free of visible moisture at a temperature of 30°F (-1.1°C): 
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(1) Each Airship with altitude engines using fuel metering devices tending to prevent icing 

has a preheater that, with the engines at 60% of maximum continuous power, can provide a 

temperature rise of: 

(i) 100°F (56°C); or 

(ii) 40°F (22°C), if a fluid de-icing system meeting the requirements of 14 CFR part 

23.1095 through 23.1099 is installed; 

(2) Each Airship with sea level engine(s) using a fuel metering device tending to prevent 

icing has a sheltered alternate source of air with a preheat temperature rise of not less than 

60°F (33°C) with the engines at 75% of maximum continuous power;

(3) Each Airship with sea level or altitude engine(s) using fuel injection systems having 

metering components on which impact ice may accumulate has a preheater capable of 

providing a temperature rise of 75°F (42°C) when the engine is operating at 75% of its 

maximum continuous power; and:

(4) Each Airship with sea level or altitude engine(s) using fuel injection systems not 

having fuel metering components projecting into the airstream on which ice may form, and 

introducing fuel into the air induction system downstream of any components or other 

obstruction on which ice produced by fuel evaporation may form, has a sheltered alternate 

source of air with a preheat temperature rise of not less than 60°F (33°C) with the engines 

at 75% of its maximum continuous power.

(b) Turbine engines 

(1) It shall be demonstrated each turbine engine and its air-inlet system must operate 

throughout the flight-power range of the engine (including idling), within the limitations 

established for the Airship, without the accumulation of ice on engine or inlet system

components that would adversely affect engine operation or cause a serious loss of power 

or.

(i) Under the icing conditions specified in 14 CFR part 25 Appendix C, and

(ii) in falling, blowing, and recirculating snow without adverse effect on engine 

operation, or

(iii) if certification for flight in snow has not been requested, the engine tolerance to 

snow shall be demonstrated.

(2) Each turbine engine must idle for 30 minutes on the ground, with the air bleed available 

for engine icing protection at its critical condition, without adverse effect, in an atmosphere 

that is at a temperature between 15°F (-9°C) and 30°F (-1°C) and has a liquid water 

content not less than 0.3 grams per cubic meter in the form of drops having a mean 

effective diameter not less than 20 micrometers, followed by momentary operation at takeoff power or thrust. During the 30 minutes of idle operation, the engine may be run up 

periodically to a moderate power or thrust setting in a manner acceptable to the 

Administrator.
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(c) For Airships with reciprocating engines having superchargers or turbochargers to 

pressurize the air, the temperature rise in the air caused by that pressurizing at any altitude 

may be utilized in determining compliance with subparagraph (a) of this paragraph if the heat 

rise utilized is that which will be available, automatically, for the applicable altitudes and 

operating condition because of supercharging or turbocharging.

HCC.1101 Carburetor air preheater design

Each exhaust-heated, induction air preheater must be designed and constructed to:

(a) Ensure ventilation of the preheater when the induction air preheater is not being used 

during engine operation.

(b) Allow inspection of the exhaust manifold parts that it surrounds; and

(c) Allow inspection of critical parts of the preheater itself.

HCC.1103 Induction system ducts 

(a) Each induction system duct must have a drain to prevent the accumulation of fuel or 

moisture in the normal ground and flight attitudes. No drain may discharge where it will cause 

a fire hazard. 

(b) Each turbine air intake system must be: 

(1) Strong enough to prevent structural failure resulting from engine surging; and 

(2) Fire-resistant if it is in any fire zone for which a fire extinguishing system is required. 

(c) Each duct connected to components between which relative motion could exist must have 

means for flexibility. 

(d) For bleed air systems no hazard may result if a duct rupture or failure occurs at any point 

between the engine port and the Airship unit served by the bleed air. 

(e) For reciprocating engine installations, each induction system duct must be: 

(1) Strong enough to prevent induction system failures resulting from normal backfire 

conditions; and 

(2) Fire resistant in any compartment for which a fire extinguishing system is required. 

HCC.1105 Air intake system screens 

If induction system screens are used: 

(a) Each screen must be upstream of the fuel metering device; 

(b) No screen may be in any part of the induction system that is the only passage through 

which air can reach the engine, unless

(1) The available preheat temperature rise is at least 100°F (55.6°C), and

(2) The screen can be de-iced by heated air; 

(c) No screen may be de-iced by alcohol alone; and 

(d) It must be impossible for fuel to strike any screen 
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HCC.1107 Inter-coolers and after-coolers 

Each inter-cooler and after-cooler must be able to withstand any vibration, inertia, and air 

pressure load to which it would be subjected in operation. 

HCC.1108 Induction system filters 

If an air filter, is used to protect the engine against foreign material particles in the induction air 

supply, it must be capable of withstanding the effects of temperature extremes, rain, fuel, oil, and 

solvents to which it is expected to be exposed in service and maintenance. 

HCC.1109 Turbocharger bleed air system

The following applies to turbocharged bleed air systems used for cabin air systems:

(a) The cabin air system may not be subject to hazardous contamination following any 

probable failure of the turbocharger or its lubrication system.

(b) The turbocharger supply air must be taken from a source where it cannot be contaminated 

by harmful or hazardous gases or vapors following any probable failure or malfunction of the 

engine exhaust, hydraulic, fuel or oil system.

HCC.1111 Turbine engine bleed-air system 

For turbine engine bleed-air systems, the following apply. 

(a) No hazard may result if duct rupture or failure occurs anywhere between the engine port 

and the Airship unit served by the bleed air. 

(b) The effect on Airship and engine performance of using maximum bleed air must be 

established.

(c) Hazardous contamination of cabin air systems may not result from failures of the engine 

lubricating system. 

(d) Bleed air must not discharge directly on any Airship component (e.g. windshield) unless 

such discharge is shown to cause no hazard to the Airship under all operating conditions.

EXHAUST SYSTEM 

HCC.1121 General 

(a) Each exhaust system must ensure safe disposal of exhaust gases without fire hazard or 

carbon monoxide contamination in any crew or passenger compartment. For test purposes, 

any acceptable carbon monoxide detection method may be used to show the absence of 

carbon monoxide. 

(b) Each exhaust system part with a surface hot enough to ignite flammable fluids or vapors 

must be located or shielded so that leakage from any system carrying flammable fluids or 

vapors will not result in a fire caused by impingement of the fluids or vapors on any part of 

the exhaust system including shields for the exhaust system.

(c) Each component that hot exhaust gases could strike, or that could be subjected to high 

temperatures from exhaust system parts, must be fireproof. All exhaust system components 

must be separated by fireproof shields from adjacent parts of the Airship that are outside the 

engine compartment. 
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(d) No exhaust gases may discharge near any flammable fluid, vent, or drain that may cause a 

fire hazard. 

(e) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a 

temperature high enough to ignite any flammable fluids or vapors external to the shroud. 

(f) No exhaust gases may be discharged where they will cause a glare seriously affecting pilot 

vision at night. 

(g) If significant traps exist, each turbine engine exhaust system must have drains discharging 

clear of the Airship, in any normal ground and flight attitude, to prevent fuel accumulation 

after the failure of an attempted engine start. 

(h) Each exhaust heat exchanger must incorporate means to prevent blockage of the exhaust 

port after any internal heat exchanger failure. 

HCC.1123 Exhaust piping 

(a) Each exhaust piping must be fireproof and corrosion-resistant, and must have means to 

prevent failure due to expansion caused by operating temperatures. 

(b) Each exhaust piping must be supported to withstand the vibration and inertia loads to 

which it may be subjected in operation. 

(c) Parts of the exhaust system connected to components between which relative motion could 

exist must have means for flexibility. 

HCC.1125 Exhaust heat exchangers 

For reciprocating engine-powered Airships, the following apply: 

(a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, 

inertia, and other loads to which it will be subject in normal operation. In addition: 

(1) Each exchanger must be suitable for continued operation at high temperatures and 

resistant to corrosion from exhaust gases; 

(2) There must be means for inspection of the critical parts of each exchanger; 

(3) Each exchanger must be ventilated wherever it is subject to contact with exhaust gases. 

(4) No exhaust heat exchanger or muffler may have any stagnant areas or liquid traps that 

would increase the probability of ignition of flammable fluids or vapors that might be 

present in case of the failure or malfunction of components carrying flammable fluids.

(b) If an exhaust heat exchanger is used for heating ventilating air: 

(1) There must be a secondary heat exchanger between the primary exhaust gas heat 

exchanger and the ventilating air system; or 

(2) Other means must be used to preclude the harmful contamination of the ventilating air. 

POWERPLANT CONTROLS AND ACCESSORIES 

HCC.1141 Powerplant controls: general 

Each powerplant control must be located, arranged, and designed under HCC.777 and 779 and 

marked under HCC.1555. In addition, it must meet the following requirements: 
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(a) Each control must be located so that it cannot be operated inadvertently by persons 

entering, leaving, or moving normally in the cockpit. 

(b) Each flexible control must be approved or must be shown to be suitable for the particular 

application. 

(c) Each control must have sufficient strength and rigidity to withstand operating loads 

without failure and without excessive deflection. 

(d) Each control must be able to maintain any set position without constant attention by flightcrew members and without creep due to control loads or vibration. 

(e) The portion of each powerplant control located in a designated fire zone that is required to 

be operated in the event of fire must be at least fire resistant. (See HCC.903(c)(2).) 

(f) Powerplant valve controls located in the cockpit must have 

(1) For manual valves, positive stops or in the case of fuel valves suitable index provisions, 

in the open and closed positions; and 

(2) In the case of valves controlled from the cockpit other than by mechanical means, 

where the correct functioning of such a valve is essential for the safe operation of the 

Airship, a valve position indicator operated by a system which senses directly that the 

valve has attained the position selected, unless other indications in the cockpit give the 

flight crew a clear indication that the valve has moved to the selected position. 

HCC.1143 Engine controls 

(a) Power or thrust control to each engine must receive unique individual commands through 

the Vehicle Management Computer. Individual cockpit control for starting and shutting down 

each thruster must be provided.

(b) The controls must be grouped and arranged to allow: 

(1) Independent start-up and shut-down of engines.

(2) Simultaneous control of all functionally related engines. 

(c) Each power/thrust control must give a positive and immediately response in controlling 

the thrusters.

(d) Reserved

(e) If a power or thrust control incorporates a fuel-shut-off feature, the control must have a 

means to prevent the inadvertent movement of the control into the shut-off position. The 

control must

(1) Have a positive lock or stop at the idle position; 

(2) Require a separate and distinct operation to place the control in the shut-off position. 

HCC.1145 Ignition switches 

(a) Ignition switches must control each ignition circuit on each engine. 

(b) There must be means to shut off quickly all ignition either by a group of switches or by a 

master ignition control. 
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(c) Each group of ignition switches, except ignition switches for turbine engines for which 

continuous ignition is not required, and each master ignition control must have a means to 

prevent its inadvertent operation. 

(d) Pre-glow switches for Diesel engines are to be treated the same as ignition switches. 

HCC.1147 Mixture controls 

(a) If there are mixture controls, each engine must have a separate control and each mixture 

control must have guards or must be shaped or arranged to prevent confusion by feel with 

other controls. 

(1) The controls must be grouped and arranged to allow: 

(i) Separate control of each engine; and: 

(ii) Simultaneous control of all functionally related engines. 

(2) The control must require a separate and distinct operation to move the control towards 

lean or shut-off position. 

(b) Each manual engine mixture control must be designed so that, if the control separates at 

the engine fuel metering device, the Airship is capable of continuing safe flight. 

HCC.1149 Propeller speed and pitch controls 

(a) If there are propeller speed or pitch controls, they must be grouped and arranged to allow 

(1) Separate control of each propeller;

(2) Simultaneous control of all functionally related propellers. 

(b) The controls must allow ready synchronization of all propellers on Airships. 

(c) The propeller speed and pitch controls must be to the right of, and at least 1 inch (25.4 

mm) below, the pilot's throttle controls. 

HCC.1153 Propeller feathering controls 

(a) If there are propeller feathering controls, each propeller must have a separate control. Each 

control must have means to prevent inadvertent operation. 

(b) If feathering is accomplished by movement of the propeller pitch or speed control lever, 

there must be means to prevent the inadvertent movement of this lever to the feathering 

position during normal operation. 

HCC.1157 Carburetor air temperature controls

If there is a carburetor air temperature control, it must be separate for each engine.

HCC.1161 Fuel jettisoning system controls 

Each fuel jettisoning system control must have guards to prevent inadvertent operation. No 

control may be near any fire extinguisher control or any other control used to combat fire. 

HCC.1163 Powerplant accessories 

(a) Each engine-driven accessory must: 
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(1) Be approved for mounting on the engine involved; 

(2) Use the provisions on the engine for mounting; 

(3) Be sealed to prevent contamination of the engine oil system and the accessory system. 

(b) Electrical equipment subject to arcing or sparking must be installed to minimize the 

probability of contact with any flammable fluids or vapors that might be present in a free 

state.

(c) Each generator rated at or more than 6 kW must be designed and installed to minimize the 

probability of a fire hazard in the event it malfunctions.

(d) If the continued rotation of any accessory remotely driven by the engine is hazardous 

when malfunctioning occurs, a means to prevent rotation without interfering with the 

continued operation of the engine must be provided. 

(e) The generator cooling provisions must be able to maintain the temperatures of generator 

components within the established temperature limits during ground and flight operations. 

(f) Each accessory driven by a gearbox that is not approved as part of the powerplant driving 

the gearbox must: 

(1) Have torque limiting means to prevent the torque limits established for the affected 

drive from being exceeded; 

(2) Use the provisions on the gearbox for mounting; and 

(3) Be sealed to prevent contamination of the gearbox oil system and the accessory system. 

HCC.1165 Engine ignition systems 

(a) Each battery ignition system must be supplemented by a generator that is automatically 

available as an alternate source of electrical energy to allow continued engine operation if any 

battery becomes depleted. 

(b) The capacity of batteries and generators must be large enough to meet the simultaneous 

demands of the engine ignition system and the greatest demands of any electrical system 

components that draw electrical energy from the same source. 

(c) The design of the engine ignition system must account for: 

(1) the condition of an inoperative generator; 

(2) the condition of a completely depleted battery with the generator running at its normal 

operating speed; and 

(3) the condition of a completely depleted battery with the generator operating at idling 

speed, if there is only one battery. 

(d) There must be means to warn appropriate crew members if malfunctioning of any part of 

the electrical system is causing the continuous discharge of any battery used for engine 

ignition. 

(e) No ground wire for any engine may be routed through a fire zone of another engine unless 

each part of that wire within that zone is fireproof. 
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(f) Each ignition system must be independent of any electrical circuit not used for assisting, 

controlling, or analyzing the operation of that system.

(g) There must be means to warn appropriate flight-crew members if the malfunctioning of 

any part of the electrical system is causing the continuous discharge of any battery necessary 

for engine ignition. 

(h) Each engine ignition system must be considered an essential electrical load. 

HCC.1166 FADEC Controlled Engines

(a) For electronic engine control system installations, it must be established that no single 

failure or malfunction or probable combinations of failures of Electronic Engine Control 

(EEC) system components will have an effect on the system, as installed in the airship, that 

causes the Loss of thrust control (LOTC)/Loss of power control (LOPC) probability of the 

system to exceed those allowed in 14 CFR part 33 certification. NOTE: The term “probable” 

in the context of “probable combination of failures” does not have the same meaning as in AC 

23.1309-1D. The term “probable” in “probable combination of failure” means “foreseeable,” 

or (in AC 23.1309-1D terms), “not extremely improbable.”

(b) Electronic engine control system installation must be evaluated for environmental and 

atmospheric conditions, including lightning. The EEC system lightning and HIRF effects that 

result in LOTC/LOPC should be considered in the Functional Hazard Assessment (FHA).

(c) The components of the installation must be constructed, arranged, and installed so as to 

ensure their continued safe operation between normal inspections or overhauls.

HCC.1167 Vectored thrust controls 

If thrust vectoring is provided, the following requirements must be met:

(a) each vectoring control must be independent of all other controls, if appropriate, and must 

provide a positive and immediate response. 

(b) the vector controls must be readily available to the pilot, and must be such that the pilot 

can readily and positively select each appropriate vectored thrust unit. 

(c) if separate vector controls are provided for each propulsive unit:

(1) they must be arranged to allow:

(i) separate control and 

(ii) simultaneous control of all functionally related units; 

(2) the Airship must be demonstrated to have safe flight characteristics when the vectored 

thrust units are in the normal flight position on one side and in the fully vectored position 

on the other, with engines operating at maximum takeoff power.

(d) in the event of a vectoring-system failure, an auxiliary means must be provided to return 

the system to a normal-operating position, if failures are harmful. 
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POWERPLANT FIRE PROTECTION 

HCC.1181 Designated fire zones: regions included 

(a) Designated fire zones are -

(1) The engine power section; 

(2) The engine accessory section; 

(3) Any complete powerplant compartment in which no isolation is provided between the 

engine power section and the engine accessory section; 

(4) Reserved

(5) The compressor and accessory sections of turbine engines; and 

(6) Combustor, turbine, and tailpipe sections of turbine engine installations that contain 

lines or components carrying flammable fluids or gases.

(b) Each designated fire zone must meet the requirements of HCC.869, 1185 to 1203. 

(c) Each Airship must: 

(1) Be designed and constructed so that no fire originating in any fire zone can enter, either 

through openings or by burning through external skin, any other zone or region where it

would create additional hazards; 

(2) Reserved

(3) Have fireproof skin in areas subject to flame if a fire starts in the engine power or 

accessory section. 

HCC.1182 Nacelle areas behind firewalls, and engine pod attaching structures containing 

flammable fluid lines 

(a) Each nacelle area immediately behind the firewall, and each portion of any engine pod 

attaching structure containing flammable fluid lines, must meet each requirement of 

HCC.1103, 1165 (e), 1183, 1185 (c), 1187, 1189 and HCC.1195 to 1203, including those 

concerning designated fire zones. However, engine pod attaching structures need not contain 

fire detection or extinguishing means. 

HCC.1183 Flammable fluid-carrying components 

(a) Except as provided in subparagraph (b) of this paragraph, each line, fitting, and other 

component carrying flammable fluid in any area subject to engine fire conditions, and each 

component which conveys or contains flammable fluid in a designated fire zone must be fire 

resistant, except that flammable fluid tanks and supports in a designated fire zone must be 

fireproof or be enclosed by a fireproof shield unless damage by fire to any non-fireproof part 

will not cause leakage or spillage of flammable fluid. Components must be shielded or located 

to safeguard against the ignition of leaking flammable fluid. 

(b) Subparagraph (a) of this paragraph does not apply to: 
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(1) Lines, fittings and components which are already approved as part of a type certificated 

engine; and: 

(2) Vent and drain lines, and their fittings, the failure of which will not result in, or add to, 

a fire hazard. 

(c) All components, including ducts, within a designated fire zone must be fireproof if, when 

exposed to or damaged by fire, they could: 

(1) Result in fire spreading to other regions of the Airship, or

(2) Cause unintentional operation of, or inability to operate, essential services or 

equipment.

HCC.1185 Flammable fluids

(a) Except for the integral oil sumps specified in HCC.1013 (a), no tank or reservoir that is a 

part of a system containing flammable fluids or gases may be in a designated fire zone unless 

the fluid contained, the design of the system, the materials used in the tank, the shut-off 

means, and all connections, lines and controls provide a degree of safety equal to that which 

would exist if the tank or reservoir were outside such a zone. 

(b) There must be at least 0.5 in (13 mm) of clear airspace between each tank or reservoir and 

each firewall or shroud isolating a designated fire zone. 

(c) Absorbent materials close to flammable fluid system components that might leak must be 

covered or treated to prevent the absorption of hazardous quantities of fluids. 

HCC.1187 Drainage and ventilation of fire zones 

(a) There must be complete drainage of each part of each designated fire zone to minimize the 

hazards resulting from failure or malfunctioning of any component containing flammable 

fluids. The drainage means must be:

(1) Effective under conditions expected to prevail when drainage is needed; and 

(2) Arranged so that no discharge fluid will cause an additional fire hazard. 

(b) Each designated fire zone must be ventilated to prevent the accumulation of flammable 

vapors.

(c) No ventilation opening may be where it would allow the entry of flammable fluids, vapors, 

or flame from other zones.

(d) Each ventilation means must be arranged so that no discharged vapors will cause an 

additional fire hazard.

(e) Unless the extinguishing agent capacity and rate of discharge are based on maximum air 

flow through a zone, there must be a means to allow the crew to shut-off sources of forced 

ventilation to any fire zone except the engine power section of the nacelle and the combustion 

heater ventilating air ducts. 

HCC.1188 Ventilation 

Each compartment containing any part of the powerplant installation must have provision for 

ventilation to prevent the accumulation of flammable vapors.
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HCC.1189 Shut-off means 

(a) Each engine installation and each fire zone specified in HCC.1181 (a)(5) and (a)(6) must 

have means to shut-off or otherwise prevent hazardous quantities of fuel, oil, and other 

flammable liquids from flowing into, within, or through any engine compartment, except that 

shut-off means are not required for:

(1) Lines, fittings, and components forming an integral part of an engine; and 

(2) Oil systems in which all components of the system in a designated fire zone, including 

the oil tanks, are fireproof or located in areas not subject to engine fire conditions.

(b) The closing of the fuel shutoff valve for any engine may not make fuel unavailable to the 

remaining engines. 

(c) Operation of any shutoff means may not interfere with the later emergency operation of 

other equipment such as propeller feathering devices. 

(d) Each flammable fluid shut-off means and control must be fireproof or must be located and 

protected so that any fire in a fire zone will not affect its operation. 

(e) No hazardous amount of flammable fluid may drain into the engine compartment after 

shutoff. 

(f) There must be means to guard against inadvertent operations of each shutoff means, and to 

make it possible for the crew to reopen the shutoff means in flight after it has been closed. 

(g) Each tank-to-engine shut-off valve must be located so that the operation of the valve will 

not be affected by powerplant or engine mount structural failure. 

(h) Each shut-off valve must have a means to relieve excessive pressure accumulation unless 

a means for pressure relief is otherwise provided in the system. 

HCC.1191 Firewalls 

(a) Each engine, fuel-burning heater and other combustion equipment intended for operation 

in flight, and the combustion, turbine, and tailpipe sections of turbine engines must be isolated 

from the rest of the Airship by firewalls, shrouds, or other equivalent means. 

(b) Each firewall or shroud must be constructed so that no hazardous quantity of liquid, gas, 

or flame can pass from the engine compartment to other part of the Airship. 

(c) Each opening in the firewall or shroud must be sealed with close-fitting, fireproof 

grommets, bushings, or firewall fittings. 

(d) Each firewall and shroud must be fireproof and protected against corrosion. 

(e) Compliance with the criteria for fireproof materials or components must be shown as 

follows. 

(1) The flame to which the materials or components are subjected must be 2000 ± 150°F 

(1100 ± 65°C); 

(2) Sheet materials approximately 10 sq in must be subjected to the flame from a suitable 

burner; 
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(3) The flame must be large enough to maintain the required test temperature over an area 

approximately 5 sq in. 

(f) Firewall materials and fittings must resist flame penetration for at least 15 minutes. 

(g) The following materials may be used in firewalls or shrouds without being tested as 

required by this paragraph: 

(1) Stainless steel sheet, 0.015 in (0.38 mm) thick. 

(2) Mild steel sheet (coated with aluminum or otherwise protected against corrosion) 0.018 

in (0.45 mm) thick.

(3) Terne plate, 0.018 in (0.45 mm) thick. 

(4) Monel metal, 0.018 in (0.45 mm) thick. 

(5) Steel or copper base alloy firewall fittings. 

HCC.1192 Engine accessory compartment diaphragm 

For air-cooled radial engines, the engine power section and all portions of the exhaust system 

must be isolated from the engine accessory compartment by a diaphragm that meets the firewall 

requirements of HCC.1191. 

HCC.1193 Engine cowling 

(a) The cowling must be constructed and supported so that it can resist the vibration, inertia, 

and air loads to which it may be subjected in operation. 

(b) Cowling must meet the drainage and ventilation requirements of HCC.1187. 

(c) On Airships with a diaphragm isolating the engine power section from the engine 

accessory section, each part of the accessory section cowling subject to flame in case of fire in 

the engine power section of the powerplant must: 

(1) Be fireproof; and 

(2) Meet the requirements of HCC.1191. 

(d) Each part of the cowling subjected to high temperatures due to its nearness to exhaustsystem parts or exhaust gas impingement must be fireproof. 

HCC.1195 Fire extinguishing systems 

Fire extinguishing systems must be installed and compliance shown with the following. 

(a) Except for combustor, turbine, and tailpipe sections of turbine engine installations that 

contain lines or components carrying flammable fluids or gases for which a fire originating in 

these sections is shown to be controllable, a fire extinguisher system must serve each engine 

compartment. 

(b) The fire extinguishing system, the quantity of the extinguishing agent, the rate of 

discharge, and the discharge distribution must be adequate to extinguish fires. It must be 

shown by either actual or simulated flight tests that under critical airflow conditions in flight 

the discharge of the extinguishing agent in each designated fire zone specified in 

subparagraph (a) of this paragraph will provide an agent concentration capable of 
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extinguishing fires in that zone and of minimizing the probability of re-ignition. An individual 

'one-shot' system may be used for fuel burning heaters, and other combustion equipment. For 

each other designated fire zone, two discharges must be provided each of which produces 

adequate agent concentration. 

(c) The fire extinguishing system for a nacelle must be able to protect simultaneously each 

compartment of the nacelle for which protection is provided. 

HCC.1197 Fire extinguishing agents 

(a) Fire extinguishing agents must: 

(1) Be capable of extinguishing flames emanating from any burning fluids or other 

combustible materials in the area protected by the fire extinguishing system; and 

(2) Have thermal stability over the temperature range likely to be experienced in the 

compartment in which they are stored. 

(b) If any toxic extinguishing agent is used, provisions must be made to prevent harmful 

concentrations of fluid vapors (which could occur from leakage during normal Airship 

operation or as a result of discharging the fire extinguisher on the ground or in flight) from 

entering any personnel compartment, even if a defect may exist in the extinguishing system. 

This must be shown by test except for extinguishing systems built into the personnel 

compartment where:

(1) 5 lb (2.3 kg) or less of carbon dioxide is available for discharge into personnel 

compartments under established extinguishing procedures, or 

(2) Protective breathing equipment is available for each flight crew member on flight deck 

duty. 

HCC.1199 Extinguishing agent containers 

The following applies: 

(a) Each extinguishing agent container must be fitted with a pressure relief device to prevent 

the container from bursting through excessive internal pressures. 

(b) The discharge end of each discharge line from a pressure relief connection must be located 

so that discharge of the fire extinguishing agent does not damage the Airship. The line must 

also be located or protected to prevent clogging caused by ice or other foreign matter. 

(c) A means must be provided for each fire extinguishing agent container to indicate that the 

container has discharged or that the charging pressure is below the established minimum 

necessary for proper functioning. 

(d) The temperature of each container must be maintained, under intended operating 

conditions, to prevent the pressure in the container from 

(1) Falling below that necessary to provide an adequate rate of discharge; or 

(2) Rising high enough to cause premature discharge. 
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(e) If a pyrotechnic capsule is used to discharge the extinguishing agent, each container must 

be installed so that temperature conditions will not cause hazardous deterioration of the 

pyrotechnic capsule. 

HCC.1201 Fire extinguishing system materials 

The following apply: 

(a) No material in any fire extinguishing system shall be capable of reacting chemically with 

any extinguishing agent so as to create a hazard. 

(b) Each system component in an engine compartment must be fireproof. 

HCC.1203 Fire detector system 

(a) There must be approved, quick acting fire or overheat detectors in each designated fire 

zone, and in the combustion, turbine, and tailpipe sections of turbine engine installations, in 

numbers and locations ensuring prompt detection of fire in those zones. 

(b) Each fire detector must be constructed and installed so that-

(1) It will withstand the vibration, inertia, and other loads to which it may be subjected in 

operation and 

(2) There is a means to warn the crew in the event that the sensor or associated wiring 

within a designated fire zone is severed at one point, unless the system continues to 

function as a satisfactory detection system after the severing; and 

(3) There is a means to warn the crew in the event of a short circuit in the sensor or 

associated wiring within a designated fire zone, unless the system continues to function as 

a satisfactory detection system after the short circuit 

(c) No fire or overheat detector may be affected by any oil, water, other fluids or fumes that 

might be present. 

(d) There must be means to allow the crew to check, in flight, the functioning of each fire 

detector electric circuit. 

(e) Wiring and other components of each fire detector system in an engine compartment must 

be at least fire resistant. 

(f) No fire or overheat detector system component for any fire zone may pass through another 

fire zone, unless -

(1) It is protected against the possibility of false warnings resulting from fires in zones 

through which it passes; or 

(2) Each zone involved is simultaneously protected by the same detector and extinguishing 

system. 

(g) Each fire detector system must be constructed so that when it is in the configuration for 

installation it will not exceed the alarm activation time approved for the detectors using the 

response time criteria specified in the appropriate Technical Standard Order. 
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HCC.1205 Vectored thrust 

For Airships utilizing vectored-thrust systems, the engine exhaust impingement effect on the 

Airship must not cause an increase in the temperature of Airship materials or components 

beyond safe limits. 

Vectoring thrust devices and tilt propulsion units must comply with requirements HCC.1181 to 

1203 and HCC.1207, where applicable. 

HCC.1207 Compliance 

Unless otherwise specified, compliance with the requirements of HCC.1181 to 1205 must be 

shown by a full scale fire test or by one or more of the following methods: 

(a) Tests of similar powerplant configurations; 

(b) Tests of components; 

(c) Service experience of Airships or aircraft with similar powerplant configurations; 

(d) Analysis. 
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Subpart F - Equipment 

GENERAL 

HCC.1301 Function and installation 

Each item of installed equipment must: 

(a) Be of a kind and design appropriate to its intended function; 

(b) Be labeled as to its identification, function, or operating limitations, or any applicable 

combination of these factors.

(c) Be installed according to limitations specified for that equipment. 

(d) Function properly when installed; and

(e) Have all associated software and/or electronic hardware, which implements the function, 

developed using processes approved by the Administrator.

(f) For equipment that does not perform a function related to the safe operation of the airship, 

subparagraph (d) of this paragraph will only be applied to the extent necessary to determine 

that no hazard exists and subparagraph (e) of this section shall not apply.

(g) Substantiation of satisfactory operation of the airship as a total system, by cold weather 

testing or by documented evidence of satisfactory operation at low temperature, is required 

after the airship has experienced a prolonged exposure to ground ambient temperatures equal 

to or less than -31°F (-35°C) unless an alternative minimum ground ambient temperature has 

been proposed by the applicant. 

HCC.1302 Installed systems and equipment for use by the flight crew

This paragraph applies to installed equipment intended for flight-crew members’ use in the 

operation of the airship from their normally seated positions on the flight deck. This installed 

equipment must be shown, individually and in combination with other such equipment, to be 

designed so that qualified flight-crew members trained in its use can safely perform their tasks 

associated with its intended function by meeting the following requirements:

(a) Flight deck controls must be installed to allow accomplishment of these tasks and 

information necessary to accomplish these tasks must be provided.

(b) Flight deck controls and information intended for flight crew use must:

(1) Be presented in a clear and unambiguous form, at resolution and precision appropriate 

to the task.

(2) Be accessible and usable by the flight crew in a manner consistent with the urgency, 

frequency, and duration of their tasks, and 

(3) Enable flight crew awareness, if awareness is required for safe operation, of the effects 

on the airship or systems resulting from flight crew actions.

(c) Operationally-relevant behavior of the installed equipment must be:

(1) Predictable and unambiguous, and

(2) Designed to enable the flight crew to intervene in a manner appropriate to the task.
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(d) To the extent practicable, installed equipment must enable the flight crew to manage errors 

resulting from the kinds of flight crew interactions with the equipment that can be reasonably 

expected in service, assuming the flight crew is acting in good faith. This sub-paragraph (d) 

does not apply to skill-related errors associated with manual control of the airship.

HCC.1303 Flight and navigation instruments 

All flight and navigation instruments must have characteristics suitable for use in the particular 

Airship considered. The presentation must be clear and unambiguous. The following instruments 

are required: 

(a) at each pilot station: 

(1) airspeed indicator; 

(2) ground speed indicator;

(3) altimeter (sensitive); 

(4) rate-of-climb indicator; 

(5) pitch attitude indicator; 

(6) gyroscopic rate-of-turn indicator;

(7) gyroscopically stabilized direction indicator (magnetic or non-magnetic).

(b) to be visible from each pilots station: 

(1) free air temperature indicator; 

(2) magnetic direction indicator; 

(3) clock; 

(4) Means to indicate pressure: 

(i) Reserved

(ii) for non-rigid Airships: in the envelope, ballonets and the outside air; 

(iii) lights to indicate to the pilot that lifting gas valves are open. The applicant has to 

demonstrate if this may be hazardous and requires immediate pilot corrective action 

(red alert). 

(5) means for measuring the temperature differential between the lifting gas and the 

outside air; 

(6) position indicators for the flight controls, engines/propellers and adjustable propeller 

blades; 

HCC.1305 Powerplant instruments 

(a) The following are required powerplant instruments for all Airships: 

(1) Fuel pressure warning means for each engine, or a master warning means for all 

engines with provision for isolating the individual warning means from the master warning 

means. 
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(2) Fuel-quantity indicator for each fuel tank; 

(3) Oil-quantity indicator for each oil tank; 

(4) Oil pressure warning means for each engine, or a master warning means for all engines 

with provision for isolating the individual warning means from the master warning means. 

(5) Reserved

(6) Oil-temperature indicator for each engine and for each turbocharger oil system that is 

separate from other oil systems; 

(7) Fire-warning devices that provide visual and audible warning; 

(8) Reserved

(9) Any other instrumentation or warning means as listed in the Engine Type Certificate 

Data Sheet or in equivalent Installation Instructions which is necessary to ensure safe 

operation of the Airship. 

(10) If the engine compartment is accessible with the engine running, during flight for 

maintenance, essential engine indicators are to be installed also in the engine 

compartments. 

(11) Instrumentation to indicate the functioning of the propeller ice-protection- and/or deicing-system;

(12) Position indicating means to indicate to the flight crew the propeller blade angle and 

the thrust direction;

(b) For reciprocating engine-powered Airships in addition to the powerplant instruments 

required by subparagraph (a) of this paragraph, the following powerplant instruments are 

required. 

(1) Tachometer for each engine; 

(2) Cylinder head temperature indicator if the engine is not liquid cooled; 

(3) Fuel-pressure or fuel flow indicator (to indicate the pressure or flow at which the fuel is 

supplied) for each pump-fed engine; 

(4) Manifold-pressure indicator for each altitude engine and for each engine with a 

controllable propeller, unless the engine is controlled by a FADEC. Manifold pressure is 

not required for a diesel engine.

(5) Induction system air temperature indicator for each engine equipped with a preheater 

and having induction air temperature limitations that can be exceeded with preheat. 

(6) For each turbocharger installation: 

(i) If limitations are established for either carburetor (or manifold) air inlet temperature 

or exhaust gas or turbocharger turbine inlet temperature, indicators must be furnished 

for each temperature for which the limitation is established unless it is shown that the 

limitation will not be exceeded in all intended operations.
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(ii) If its oil system is separate from the engine oil system, oil pressure and oil 

temperature indicators must be provided. 

(7) A coolant temperature indicator for each liquid-cooled engine. 

(c) For turbine engine-powered Airships in addition to the powerplant instruments required by 

subparagraph (a) of this paragraph, the following powerplant instruments are required. 

(1) Gas-temperature indicator for each engine; 

(2) Fuel flowmeter for each engine; 

(3) Tachometer (to indicate the speed of the rotors with established limiting speeds) for 

each engine; 

(4) A means to indicate, to the flight crew, the operation of each engine starter that can be 

operated continuously but that is neither designed for continuous operation nor designed to 

prevent hazard if it has failed; 

(5) An indicator for the functioning of the powerplant ice protection system for each 

engine; this applies only to a system which is selectable or contains some means of 

regulation. 

(6) An indicator for the fuel strainer or filter required by HCC.997 to indicate the 

occurrence of contamination of the strainer or filter before it reaches the capacity 

established in accordance with subparagraph 997(d); 

(7) A warning means for the oil strainer or filter required by HCC.1019, if it has no bypass, 

to warn the crew of the occurrence of contamination of the strainer or filter screen before it 

reaches the capacity established in accordance with subparagraph 1019(a)(2); 

(8) An indicator for the proper functioning of any heater used to prevent ice clogging of 

fuel-system components. 

(d) For turbopropeller-powered Airships a torque indicator for each engine is required in 

addition to the powerplant instruments required by paragraphs (a) and (c) of this paragraph.

(e) Reserved

(f) Reserved

(g) Thruster system: 

(1) For both fixed and variable angle thrusters the following is required: 

(i) Oil pressure indicator for each pressure-lubricated gearbox; 

(ii) Oil pressure warning device for each pressure-lubricated gearbox to indicate when 

the oil pressure falls below a safe value; 

(iii) Oil quantity indicator for each oil tank and each rotor drive gearbox, if lubricant is 

self-contained; 

(iv) Oil temperature warning device to indicate unsafe oil temperatures in each thruster 

drive gearbox. 
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(v) thrust direction indicator 

(vi) thrust magnitude indicator 

(2) For each variable angle thruster a thrust vector angle position indicator is required. 

HCC.1306 Miscellaneous equipment instruments 

The following are additional required instruments for auxiliary systems, if installed: 

(a) Electrical power generating systems: 

(1) Volt/load meter for each DC generating system; 

(2) Volt/frequency meter for each AC generating system. 

(b) Reserved

(c) Indicators to show: 

(1) if the external ballonet valves are open; 

(2) if the air to gas (ballonet to gas envelope) valves are open; and an indicator to show the 

ballonet blowers are on. Caution/warning logic will be incorporated in the system to detect 

if the ballonets are inflating the envelope in the case of an envelope tear. 

(3) When ballonets are fully inflated.

(d) Hydraulic systems: 

(1) Hydraulic-quantity gauge for each system (dipstick or sight gauge); 

(2) Hydraulic-pressure gauge for each system. 

(e) Fly-by-wire / Fly-by-light flight control system: a means to indicate control surface 

position to the crew relative to commanded position

(f) Indicators for disposable ballast (if liquid ballast include fill level and temperature 

indicators) and disposable cargo mass and distribution.

(g) Indicators for the position of the locks for disposable ballast or cargo.

(h) A means to indicate computed mass and balance changes in the mass exchange system (if 

a mass exchange system is installed, such as a water system).

HCC.1307 Miscellaneous equipment 

The following miscellaneous equipment is required: 

(a) A seat or berth for each occupant or watch; 

(b) Reserved

(c) Electrical protective devices, as prescribed in these criteria. 

(d) Two systems for two-way radio communications, with controls for each accessible from 

each pilot station, designed and installed so that failure of one system will not preclude 

operation of the other system. The use of a common antenna system is acceptable if adequate 

reliability is shown. 
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(e) Two systems for radio navigation, with controls for each accessible from each pilot station 

designed and installed so that failure of one system will not preclude operation of the other 

system. The use of a common antenna system is acceptable if adequate reliability is shown. 

(f) A public address system that can be made audible for all occupants; 

(g) An emergency location transmitter, the transmitter must be of a kind that is manually 

activatable and accessible during flight from a flight crew member station;

(h) A cockpit voice recorder (CVR); 

(i) A flight data recorder (FDR); 

(j) A mode S transponder. 

HCC.1309 Equipment, systems, and installations 

The requirements of this paragraph, except as identified below, are applicable, in addition to 

specific design requirements of HCC, to any equipment or system installed in the Airship. 

Although this paragraph does not apply to the performance and flight characteristic requirements 

of Subpart B and the structural requirements of Subparts C and D, it does apply to any system on 

which compliance with any of those requirements is dependent. Certain single failures or jams 

covered by HCC.671(c)(1) and HCC.671(c)(3) are excepted from the requirements of 

HCC.1309(b)(1)(ii). The failure effects covered by HCC.810 and HCC.812 are excepted from 

the requirements of HCC.1309(b). The requirements of HCC.1309(b) apply to powerplant 

installations as specified in HCC.901. 

(a) The Airship equipment and systems must be designed and installed so that: 

(1) Those required for type certification or by operating rules, or improper functioning of 

which would reduce safety, perform as intended under the Airship's operating and 

environmental conditions. 

(2) Other equipment and systems are not a source of danger in themselves and do not 

adversely affect the proper functioning of those covered by sub-paragraph (a)(1) of this 

paragraph. 

(b) The Airship systems and associated components, considered separately and in relation to 

other systems, shall be designed so that: 

(1) Any catastrophic failure condition 

(i) is extremely improbable; and 

(ii) does not result from a single failure; and 

(2) Any hazardous failure condition is extremely remote; and 

(3) Any major failure condition is remote. 

(c) Information concerning unsafe system operating conditions shall be provided to the crew 

to enable them to take appropriate corrective action. A warning indication must be provided if 

immediate corrective action is required. Systems and controls, including indications and 

annunciations must be designed to minimize crew errors which could create additional 

hazards.
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HCC.1310 Power source capacity and distribution 

(a) Each installation, the functioning of which is required for type certification or by operating 

rules and that requires a power supply is an "essential load" on the power supply. The power 

sources and the system must be able to supply the following power loads in probable 

operating combinations and for probable durations.

(1) Loads connected to the system with the system functioning normally. 

(2) Essential loads, after failure of any one prime mover, power converter, or energy 

storage device. 

(3) Essential loads after failure of the most critical engine. One engine inoperative should 

be considered for all transport Airships. 

After the failure of the most critical engine, those services essential to airworthiness must 

continue to function and perform adequately within the limits of operation implied by the 

emergency conditions. 

(4) Essential loads for which an alternate source of power is required, after any failure or 

malfunction in any one power supply system, distribution system, or other utilization 

system.

(b) In determining compliance with sub-paragraphs (a)(2) and (3) of this paragraph, the power 

loads may be assumed to be reduced under a monitoring procedure consistent with safety in 

the kinds of operation authorized. Loads not required in controlled flight need not be 

considered for the two-engine-inoperative condition on Airships with three engines or the 

any-number-but-two-engine-inoperative condition on Airships with four-or-more engines.

HCC.1316 Electrical and electronic system lightning protection 

(a) Each electrical and electronic system that performs a function, for which failure would 

prevent the continued safe flight and landing of the airship, must be designed and installed so 

that—

(1) The function is not adversely affected during and after the time the airship is exposed to 

lightning; and 

(2) The system automatically recovers normal operation of that function in a timely 

manner after the airship is exposed to lightning. 

(b) For airships approved for instrument flight rules operation, each electrical and electronic 

system that performs a function, for which failure would reduce the capability of the airship

or the ability of the flightcrew to respond to an adverse operating condition, must be designed 

and installed so that the function recovers normal operation in a timely manner after the 

airship is exposed to lightning

HCC.1317 High-Intensity Radiated Fields (HIRF) Protection

(a) Except as provided in paragraph (d) of this section, each electrical and electronic system 

that performs a function whose failure would prevent the continued safe flight and landing of 

the airship must be designed and installed so that--
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(1) The function is not adversely affected during and after the time the airship is exposed to 

HIRF environment I, as described in 14 CFR part 23 Appendix J;

(2) The system automatically recovers normal operation of that function, in a timely 

manner, after the airship is exposed to HIRF environment I, as described in 14 CFR part 23 

Appendix J, unless the system's recovery conflicts with other operational or functional 

requirements of the system; and

(3) The system is not adversely affected during and after the time the airship is exposed to 

HIRF environment II, as described in 14 CFR part 23 Appendix J.

(b) Each electrical and electronic system that performs a function whose failure would 

significantly reduce the capability of the airship or the ability of the flightcrew to respond to 

an adverse operating condition must be designed and installed so the system is not adversely 

affected when the equipment providing the function is exposed to equipment HIRF test level 

1 or 2, as described in 14 CFR part 23 Appendix J.

(c) Each electrical and electronic system that performs a function whose failure would reduce 

the capability of the airship or the ability of the flightcrew to respond to an adverse operating 

condition must be designed and installed so the system is not adversely affected when the 

equipment providing the function is exposed to equipment HIRF test level 3, as described in 

14 CFR part 23 Appendix J.

(d) Before December 1, 2012, an electrical or electronic system that performs a function 

whose failure would prevent the continued safe flight and landing of an airship may be 

designed and installed without meeting the provisions of paragraph (a) provided—

(1) The system has previously been shown to comply with special conditions for HIRF, 

prescribed under 14 CFR part 21.16, issued before December 1, 2007;

(2) The HIRF immunity characteristics of the system have not changed since compliance 

with the special conditions was demonstrated; and

(3) The data used to demonstrate compliance with the special conditions is provided.

INSTRUMENTS: INSTALLATION 

HCC.1321 Arrangement and visibility 

Instruments and indicating devices shall be located so that they can be read easily by the 

appropriate crew member. 

(a) Each flight-, navigation-, envelope- or envelope and ballonet pressure- (whichever is 

installed) and powerplant-instrument and warning device for use by any flight crew member 

shall be so arranged as to be convenient for their purpose and must be plainly visible to 

him/her from his/her pilot station with the minimum practicable deviation from his/her normal 

position and line of vision when looking forward along the flight path. 

(b) Identical power-plant instruments must be conveniently grouped on instrument-panels in 

such a manner that the appropriate crew member(s) may see them readily. Power-plant 

instruments for each engine shall be so located that the engine to which they relate is 

indicated with certainty.

(c) Instrument panel vibration may not damage or impair the accuracy of any instrument. 
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(d) For each Airship the flight instruments required by HCC.1303 and, as applicable, by the 

operating rules must be grouped on the instrument panel and centered as near as practicable 

about the vertical plane of the crew's forward vision. In addition the following is required:

(1) the instrument that most effectively indicates the attitude must be on the panel in the 

top center position; 

(2) the instrument that most effectively indicates airspeed must be adjacent to and directly 

to the left of the instrument in the top center position; 

(3) The instrument that most effectively indicates altitude must be adjacent to and directly 

to the right of the instrument in the top center position; and; 

(4) The instrument that most effectively indicates direction of flight, other than the 

magnetic direction indicator required by HCC.1303 (b)(2), must be adjacent to and directly 

below the instrument in the top center position. 

(5) Electronic display indicators may be used for compliance with sub-paragraphs (d)(1) to 

(d)(4) of this paragraph when such displays comply with requirements in HCC.1330. 

(6) A gauge or equivalent to indicate envelope and ballonet pressure on rigid and semirigid Airships should be located near the main flight instruments. 

(e) If a visual indicator is provided to indicate malfunction of an instrument, it must be 

effective under all probable cockpit lighting conditions. 

HCC.1322 Warning, caution and advisory lights 

If warning, caution, or advisory lights are installed in the cockpit, they must, unless otherwise 

approved by the Administrator, be: 

(a) Red, for warning lights (lights indicating a hazard which requires immediate corrective 

action); 

(b) Amber, for caution lights (lights indicating the possible need for future corrective action); 

(c) Green, for safe operation lights; 

(d) Any other color, including white, for lights not described in paragraphs (a) through (c) of 

this paragraph, provided the color differs sufficiently from the colors prescribed in paragraphs 

(a) through (c) of this paragraph to avoid possible confusion.

HCC.1323 Airspeed indicating system 

(a) Each airspeed indicating instrument must be calibrated to indicate true airspeed (at sea 

level with a standard atmosphere) with a minimum practicable instrument calibration error 

when the corresponding pitot and static pressure are applied. 

(b) Each airspeed system must be calibrated in flight to determine the system error. The 

system error, including position error, but excluding the airspeed indicator instrument 

calibration error, may not exceed 5 knots throughout the range from 20 knots to VMO.

(c) Each system must be arranged, so far as practicable, to prevent malfunction or serious 

error due to the entry of moisture, dirt, or other substances. 
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HCC.1325 Static pressure systems 

(a) Each instrument provided with static pressure case connections must be so vented that the 

influence of Airship speed, the opening and closing of windows, airflow variations, moisture, 

or other foreign matter will least affect the accuracy of the instruments except as noted in 

subparagraph (b)(3) of this paragraph. 

(b) If a static pressure system is necessary for the functioning of instruments, systems, or 

devices, it must comply with the following: 

(1) The design and installation of a static pressure system must be such that 

(i) Positive drainage of moisture is provided; 

(ii) Chafing of the tubing, and excessive distortion or restriction at bends in tubing, is 

avoided; 

(iii) The materials used are durable and suitable for the purpose intended, and protected 

against corrosion. 

(2) A proof test must be conducted to demonstrate the integrity of the static pressure 

system in the following manner: Evacuate the static pressure system to a pressure 

differential of approximately 34 hPa or to a reading on the altimeter, 1000 ft above the 

Airship elevation at the time of the test. Without additional pumping for a period of 1 

minute, the loss of indicated altitude must not exceed 100 ft on the altimeter. 

(3) For those Airships intended for operation under Instrument Flight Rules or in known 

icing conditions, and if a static pressure system is provided for any instrument, device, or 

system required by the operating rules applicable, each static pressure port must be located 

in such a manner that the correlations between air pressure in the static pressure are not 

altered when the Airship encounters icing conditions. An anti-icing means or an alternate 

source of static pressure may be used in showing compliance with this requirement. If the 

reading of the altimeter, when on the alternate static pressure system differs from the 

reading of the altimeter when on the primary static system by more than 50 ft, a correction 

card must be provided for the alternate static system. 

(c) Except as provided in subparagraph (d) of this paragraph, if the static pressure system 

incorporates both a primary and an alternate static pressure source, the means for selecting 

one or the other source must be designed so that 

(1) When either source is selected, the other is blocked off; 

(2) Both sources cannot be blocked off simultaneously. 

(d) Subparagraph (c)(1) of this paragraph does not apply if it can be demonstrated that the 

static pressure system calibration, when either static pressure source is selected, is not 

changed by the other static pressure source being open or blocked. 

(e) Each system must be designed and installed so that the error in indicated pressure altitude, 

at sea level, with a standard atmosphere, excluding instrument calibration error does not result 

in an error of more than ±30 ft in the speed range between VAM and VMO. 
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HCC.1326 Pitot heat indication systems 

If a flight instrument pitot heating system is installed, an indication system must be provided to 

indicate to the flight crew when that pitot heating system is not operating. The indication system 

must comply with the following requirements: 

(a) The indication provided must incorporate an amber light that is in clear view of a flightcrew member. 

(b) The indication provided must be designed to alert the flight crew if either of the following 

conditions exist: 

(1) The pitot heating system is switched 'off'. 

(2) The pitot heating system is switched 'on' and any pitot tube heating element is 

inoperative. 

HCC.1327 Magnetic direction indicator 

(a) Except as provided in subparagraph (b) of this paragraph 

(1) Each magnetic direction indicator must be installed so that its accuracy is not 

excessively affected by the Airships vibration or magnetic fields; HW Flight Test Plan

(2) The compensated installation may not have a deviation, in level flight, greater than 10° 

on any heading. 

(b) A magnetic nonstabilized direction indicator may deviate more than 10° due to the 

operation of electrically-powered system such as electrically-heated windshields if either a 

magnetic stabilized direction indicator, which does not have a deviation in level flight greater 

than 10° on any heading, or a gyroscopic direction indicator, is installed. Deviations of a 

magnetic nonstabilized-direction indicator of more than 10° must be placarded in accordance 

with HCC.1547(e).

HCC.1329 Automatic pilot system 

If an automatic pilot system is installed, it must meet the following: 

(a) Each system must be designed so that it can be quickly and positively disengaged by the 

crew to prevent it from interfering with the control of the Airship. 

(b) Unless there is automatic synchronization, each system must have a means to indicate 

readily to the crew the alignment of the actuating device in relation to the control system it 

operates. 

(c) Each manually operated control for the system's operation must be readily accessible to 

the flight crew. Each control must operate in the same plane and sense of motion as the 

corresponding primary flight control. The direction of motion must be plainly indicated on or 

near each control. 

(d) Each system must be designed and adjusted so that, within the range of adjustment 

available to the flight crew, it cannot produce hazardous loads on the Airship or create 

hazardous deviations in the flight path, under any flight condition appropriate to its use, either 

during normal operation or in the event of a malfunction, assuming that correction action 

begins within a reasonable period of time (e.g. recognition plus 5 seconds). 
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(e) Each system must be designed so that a single malfunction will not produce a hardover 

signal in more than one control axis. If the automatic pilot integrates signals from auxiliary 

controls or furnishes signals for operation of other equipment, positive interlocks and 

sequencing of engagement to prevent improper operation are required. 

(f) There must be protection against adverse interaction of integrated components, resulting 

from a malfunction. 

(g) Means must be provided to indicate to the flight crew the current mode of operation and 

any modes armed by the flight crew. Selection switch position is not acceptable as a means of 

indication. 

(h) Vectored thrusters or bow/tail thrusters shall not be connected to the autopilot system, 

unless safe integration with the functioning of the normal flight controls can be demonstrated. 

(i) An automatic station keeping system or hovering system must meet the requirements (a) 

through (h), if applicable. 

HCC.1330 Electronic flight instrument system (EFIS) 

Electronic display systems may be installed provided: 

(a) they are easily legible under all lighting conditions encountered in the cockpit, including 

direct sunlight; 

(b) the requirements in HCC.1303, 1305 and 1321 are met; 

(c) they incorporate sensory cues for the crew that are equivalent to those in the instruments 

being replaced by the electronic display units; 

(d) they incorporate visual display of instrument markings required by HCC.1541 through 

1553, or visual display that alert the crew to abnormal operational values, or approaches to 

unsafe values, of any parameter required to be displayed by these criteria. 

HCC.1331 Instruments using a power supply 

For each instrument required by HCC.1303 (b) that uses a power supply, the following apply: 

(a) Each instrument must have a visual means integral with the instrument, to indicate when 

power adequate to sustain proper instrument performance is not being supplied. The power 

must be measured at or near the point where it enters the instruments. For electric instruments, 

the power is considered to be adequate when the voltage is within approved limits. 

(b) Each instrument must, in the event of the failure of one power source, be supplied by 

another power source. This may be accomplished automatically or by manual means. The 

failure of one power source must not affect the instruments of all crew stations. 

(c) If an instrument presenting flight and/or navigation data receives information from sources 

external to that instrument and loss of that information would render the presented data 

unreliable, a clear and unambiguous visual warning must be given to the crew when such loss 

of information occurs that the presented data cannot be relied upon. 

HCC.1333 Instrument systems 

For systems that operate the instruments required by HCC.1303 (a) which are located at each 

pilot's station: 
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(a) Means must be provided to connect the required instruments at the first pilot's station to 

operating systems which are independent of the operating systems at other flight crew 

stations, or other equipment; 

(b) The equipment, systems, and installations shall be designed so that sufficient information 

is available to assure control of the Airship in speed, altitude, heading and pitch by one of the 

pilots without immediate crew action after any single failure or combination of failures that is 

not assessed to be extremely improbable and 

(c) Additional instruments, systems, or equipment shall not be connected to the operating 

systems for the required instruments, unless provisions are made to ensure the continued 

normal functioning of the required instruments in the event of any malfunction of the 

additional instruments, systems, or equipment which is not shown to be extremely 

improbable. 

HCC.1335 Flight director systems 

If a flight director system is installed, means must be provided to indicate to the flight crew its 

current mode of operation and any modes armed by the flight crew. Selector switch position is 

not acceptable as a means of indication. 

HCC.1337 Powerplant instruments 

(a) Instruments and instrument lines: 

(1) each powerplant instrument line must meet the requirements of HCC.993 and 1183. 

(2) each line carrying flammable fluids under pressure must: 

(i) have restricting orifices or other safety devices at the source of pressure to prevent 

the escape of excessive fluid if the line fails; 

(ii) be installed and located so that the escape of fluids would not create a hazard. 

(3) Each powerplant instrument that utilizes flammable fluids must be installed and located 

so that the escape of fluid would not create a hazard. 

(b) Fuel quantity indicator: There must be a means to indicate to the flight crew members the 

quantity of fuel in each tank during flight. An indicator, calibrated in liters, kilograms or 

equivalent units and clearly marked to indicate which scale is being used, may be used. In 

addition:

(1) Each fuel-quantity indicator must be calibrated to read 'zero' during level flight when 

the quantity of fuel remaining in the tank is equal to the unusable fuel quantity determined 

under HCC.959; 

(2) Each exposed sight gauge used as a fuel-quantity indicator must be protected against 

damage; 

(3) Tanks with interconnected outlets and airspaces may be considered as one tank and 

need not have separate indicators; 
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(4) No fuel-quantity indicator is required for a small auxiliary tank that is used only to 

transfer fuel to other tanks if the relative size of the tank, the rate of fuel transfer, and 

operating instructions are adequate to 

(i) Guard against overflow; 

(ii) Give the flight crew members prompt warning if transfer is not proceeding as 

planned. 

(c) Fuel flow meter system: If a fuel flow meter system is installed, each metering component 

must have a means to bypass the fuel supply if malfunctioning of that component severely 

restricts fuel flow. 

(d) Oil-quantity indicator: There must be a means to indicate the quantity of oil in each tank:

(1) on the ground; 

(2) in flight, to the flight crew members, if there is an oil transfer system, or a reserve oilsupply system. 

ELECTRICAL SYSTEMS AND EQUIPMENT 

HCC.1351 General 

(a) Electrical system capacity: the required generating capacity, and number and types of 

power sources must: 

(1) Be determined by an electrical load analysis; and 

(2) Meet the requirements of HCC.1309 and 1310. 

(b) Generating system: the generating system includes electrical power sources, main power 

buses, transmission cables, and associated control, regulation, and protective devices. It must 

be designed so that: 

(1) Power sources function properly when independent and when connected in 

combination; 

(2) No failure or malfunction of any power source shall create a hazard or impair the 

ability of remaining sources to supply essential loads; 

(3) The system voltage and frequency (as applicable) at the terminals of all essential load 

equipment is maintained within the limits for which the equipment is designed, during any 

probable operating condition; 

(4) System transients due to switching, fault clearing, or other causes do not make essential 

loads inoperative, and do not cause a smoke or fire hazard; 

(5) There are means accessible where necessary, in flight, to appropriate crew members for 

the individual and rapid disconnection of each electrical power source; and: 

(6) There are means to indicate to appropriate crew members the generating system 

capacities essential for the safe operation of the system, such as the voltage and current 

supplied by each generator. 
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(c) External power: If provisions are made for connecting external power to the Airship, and 

that external power can be electrically connected to equipment other than that used for engine 

starting, means must be provided to ensure that no external power supply having a reverse 

polarity, a reverse phase sequence (including crossed phase and neutral), open circuit line, 

incorrect frequency or voltage, can supply power to the Airship's electrical system. 

(d) Operation without normal electrical power. The following apply: 

(1) Unless it can be shown that the loss of the normal electrical power generating system(s) 

is extremely improbable, alternate high integrity electrical power system(s), independent of 

the normal electrical power generating system(s), must be provided to power those services 

necessary to complete a flight and make a safe landing. 

(2) The services to be powered must include: 

(i) Those required for immediate safety and which must continue to operate following 

the loss of the normal electrical power generating system(s), without the need for flight 

crew action; 

(ii) Those required for continued controlled flight; and 

(iii) Those required for descent, approach and landing. 

(3) Failures, including junction box, control panel or wire bundle fires, which would result 

in the loss of the normal and alternate systems must be shown to be extremely improbable. 

HCC.1353 Electrical equipment and installations 

(a) Electrical equipment, controls, and wiring must be installed so that operation of any one 

unit or system of units will not adversely affect the simultaneous operation of any other 

electrical unit or system essential to the safe operation. Any electrical interference likely to be 

present in the Airship must not result in hazardous effects upon the Airship or its systems 

except under extremely remote conditions. 

(b) Cables must be grouped, routed and spaced so that damage to essential circuits will be 

minimized if there are faults in cables, particularly heavy current-carrying cables.

(c) Storage batteries must be designed and installed as follows: 

(1) Safe cell temperatures and pressures must be maintained during any probable charging 

or discharging condition. No uncontrolled increase in cell temperature may result when the 

battery is recharged (after previous complete discharge): 

(i) At maximum regulated voltage or power; 

(ii) During a flight of maximum duration; and 

(iii) Under the most adverse cooling condition likely to occur in service. 

(2) Compliance with subparagraph (c)(1) of this paragraph must be shown by test unless 

experience with similar batteries and installations has shown that maintaining safe cell 

temperatures and pressures presents no problem. 
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(3) No explosive or toxic gases emitted by any battery in normal operation, or as the result 

of any probable malfunction in the charging system or battery installation, may accumulate 

in hazardous quantities within the Airship. 

(4) No corrosive fluids or gases that may escape from the battery may damage surrounding 

Airship structures or adjacent essential equipment. 

(5) Each nickel-cadmium or lithium type battery installation must have provisions to 

prevent any hazardous effect on structure or essential systems that may be caused by the 

maximum amount of heat the battery can generate during a short circuit of the battery or of 

its individual cells. 

(6) Nickel-cadmium or lithium type battery installations that are not provided with lowenergy charging means must have: 

(i) A system to control the charging rate of the battery automatically so as to prevent 

battery overheating; 

(ii) A battery temperature sensing and over-temperature warning system with a means 

for disconnecting the battery from its charging source in the event of an overtemperature condition; or 

(iii) A battery failure sensing and warning system with a means for disconnecting the 

battery from its charging source in the event of battery failure. 

(d) Electrical cables and cable installations must be designed and installed as follows: 

(1) The electrical cables used must be compatible with the circuit protection devices 

required by HCC.1357, such that a fire or smoke hazard cannot be created under temporary 

or continuous fault conditions. 

(2) Means of permanent identification must be provided for electrical cables, connectors 

and terminals. 

(3) Electrical cables must be installed such that the risk of mechanical damage and/or 

damage caused by fluids, vapors, sources of heat or aging is minimized.

(4) Each electric connecting cable must be of adequate capacity. 

(5) Each cable and associated equipment that would overheat in the event of a circuit 

overload or fault must be at least flame resistant and may not emit dangerous quantities of 

toxic fumes. 

(e) Electrical bonding must provide an adequate electrical return path under both normal and 

fault conditions, on Airships having earthed electrical systems (see HCC.581). 

HCC.1355 Distribution system 

(a) The distribution system includes the distribution buses, their associated feeders, and each 

control protective device. 

(b) Reserved
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(c) If two independent sources of electrical power for particular equipment or systems are 

required by this HCC, in the event of the failure of one power source for such equipment or 

system, another power source (including its separate feeder) must be automatically provided 

or be manually selectable to maintain equipment or system operation. 

HCC.1357 Circuit protective devices 

(a) Automatic protective devices must be used to minimize distress to the electrical system 

and hazard to the Airship in the event of wiring faults or serious malfunction of the system or 

connected equipment.

(b) The protective and control devices in the generating system must be designed to deenergize and disconnect faulty power sources and power transmission equipment from their 

associated buses with sufficient rapidity to provide protection from hazardous over-voltage 

and other malfunctions.

(c) Each resettable circuit protective device must be designed so that, when an overload or 

circuit fault exists, it will open the circuit irrespective of the position of the operating control.

(d) If the ability to reset a circuit breaker or replace a fuse is essential to safety in flight, that 

circuit breaker or fuse must be located and identified so that it can be readily reset or replaced 

in flight. Where fuses are used, there must be spare fuses for use in-flight equal to at least 

50% of the number of fuses of each rating required for complete circuit protection. 

(e) Each circuit for essential loads must have individual circuit protection. However, 

individual protection for each circuit in an essential load system (such as each position light 

circuit in a system) is not required. 

(f) Reserved

(g) Automatic reset circuit breakers may be used as integral protectors for electrical 

equipment (such as thermal cut-outs) if there is circuit protection to protect the cable to the 

equipment. 

HCC.1360 Precautions against injury 

(a) Shock: the electrical system must be designed to minimize the risk of electric shock to 

crew, passengers and servicing personnel and also to maintenance personnel using normal 

precautions.

(b) Burns: the temperature rise of any part which has to be handled during normal operation 

by the flight crew must not be such as to cause dangerous inadvertent movement, or injury to 

the crew member. 

HCC.1361 Master switch arrangement 

(a) There must be a master switch to allow ready disconnection of electric power sources from 

the main bus. The point of disconnection must be adjacent to the sources controlled by the 

switch. 

(b) Load circuits may be connected so that they remain energized after they have been 

switched off, if:
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(1) The circuits are isolated, or physically shielded, to prevent their igniting flammable 

fluids or vapors that might be liberated by the leakage or rupture of any flammable fluid 

systems; and

(2) The circuits are required for continued operation of the engines; or 

(3) The circuits are protected by circuit protective devices, rated at 5 amperes or less, 

located near the electric power source. 

(c) The master switch or its controls must be so installed that the switch is easily discernible 

and accessible to a crew member in flight. 

(d) Additional local circuit breakers should be installed in the Airship if the system is 

accessible to the crew during flight, ground handling or maintenance. 

HCC.1362 Electricity supplies for emergency conditions 

A suitable electricity supply must be maintained to those services which are required, either by 

this HCC (e.g. HCC.1195) or in order for emergency procedures to be carried out, after an 

emergency landing or ditching. The circuits to these services must be designed and protected to 

minimize the risk of their causing a fire under these conditions.

HCC.1363 Electrical system tests 

(a) Tests must be made to determine that the performance of the electrical supply systems 

meets the requirements of this code under all the appropriate normal and failure conditions. 

When laboratory tests of the electrical system are conducted: 

(1) The tests must be performed on a mock-up using the same generating equipment used 

in the Airship; 

(2) The equipment must simulate the electrical characteristics and length of the distribution 

wiring and connected loads to the extent necessary for valid test results; and 

(3) Laboratory generator drives must simulate the actual prime movers on the Airship with 

respect to their reaction to generator loading, including loading due to faults. 

(b) For each flight condition that cannot be simulated adequately in the laboratory or by 

ground tests on the Airship, flight tests must be made. 

HCC.1367 Switches 

Each switch must be: 

(a) Able to carry its rated current; 

(b) Constructed with sufficient distance or insulating material between current carrying parts 

and the housing that vibration in flight will not cause short circuit: 

(c) Accessible to appropriate flight crew members; 

(d) Labeled as to operation and the circuit controlled.

LIGHTS 

HCC.1381 Instrument lights 

(a) The instrument lights must: 
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(1) Provide sufficient illumination to make each instrument, switch and other device 

necessary for safe operation easily readable unless sufficient illumination is available from 

another source; and 

(2) Be installed so that: 

(i) Their direct rays are shielded from the pilot's eyes; and 

(ii) No objectionable reflections are visible to the pilot. 

(b) Unless undimmed instrument lights are satisfactory under each expected flight condition, 

there must be a means to control the intensity of illumination. 

HCC.1383 Ground proximity and landing lights 

(a) Each ground proximity and landing light must be approved, and must be installed so that: 

(1) No objectionable glare is visible to the crew; 

(2) The pilots are not adversely affected by halation; and 

(3) It provides enough light for the intended night operation including landing. 

(4) A landing light must be installed. For IFR operation two lamps or double filament 

separately energized must be installed.

(5) A light for downward landing area illumination must be installed. 

(b) Except when one switch is used for the lights of a multiple light installation at one 

location, there must be a separate switch for each light. 

(c) If external lighting is provided for crew members other than the pilots, switching should 

be possible: 

(1) locally from the crew station, and 

(2) centrally from the pilot's seats. 

(d) If lights are retractable there must be a means to indicate to the crew when the lights are 

extended. 

HCC.1385 Position light system installation 

General: each part of each position light system must meet the applicable requirements of this 

HCC and each system as a whole must meet the requirements of HCC.1387 through HCC.1397. 

Position lights must be distributed in such a way that no aircraft crossing the Airships flight path 

might endeavor to fly between bow and stern position lights.

(a) Bow position light: the bow position light must be a white light mounted as far forward as 

possible on the envelope and must be approved. 

(b) Forward position lights: forward position lights must consist of a red and green light 

spaced laterally as far apart as practicable and installed on the widest forward part of the 

Airship so that, with the Airship in the normal flying position, the red light is on the left side 

and the green light is on the right side. Each light must be approved. 
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(c) Rearward position lights: rearward position lights must consist of a red and green light 

spaced laterally as far apart as practicable and installed on the widest rearward part of the 

Airship so that, with the Airship in the normal flying position, the red light is on the left side 

and the green light is on the right side. Each light must be approved. 

(d) Stern position light: the stern position light must be a white light mounted as far aft as 

practicable on the tail and must be approved. 

(e) Circuit: the bow position light, the two forward and rearward position lights and the stern 

position light must share a common switch. 

(f) Light covers and color filters: each light cover or color filter must be at least flame 

resistant and may not change color or shape or lose any appreciable light transmission during 

normal use.

HCC.1387 Position light system dihedral angles 

(a) Except as provided in subparagraph (f) of this paragraph, each bow, forward, rearward and 

stern position light must, as installed, show unbroken light within the dihedral angles 

described in this paragraph. 

(b) Dihedral angle F (forward) is formed by two intersecting vertical planes making angles of 

110° to the right and to the left, respectively, to a vertical plane passing through the 

longitudinal axis, as viewed when looking forward along the longitudinal axis.

(c) Dihedral angle L (left) is formed by two intersecting vertical planes, the first parallel to the 

longitudinal axis of the Airship, and the other at 110° to the left of the first, as viewed when 

looking forward along the longitudinal axis. 

(d) Dihedral angle R (right) is formed by two intersecting vertical planes, the first parallel to 

the longitudinal axis of the Airship, and the other at 110° to the right of the first, as viewed 

when looking forward along the longitudinal axis.

(e) Dihedral angle A (aft) is formed by two intersecting vertical planes making angles of 70° 

to the right and to the left, respectively, to a vertical plane passing through the longitudinal 

axis, as viewed when looking aft along the longitudinal axis.

(f) If the stern position light, when mounted as far aft a practicable in accordance with 

HCC.1385(d), cannot show unbroken light within dihedral angle A (as defined in 

subparagraph (e) of this paragraph), a solid angle or angles of obstructed visibility totaling not 

more than 0.04 steradians is allowable within that dihedral angle, if such solid angle is within 

a cone, the apex of which is at the rear position light and the elements of which make an angle 

of 30° with a vertical line passing through the rear position light. 

HCC.1389 Position light distribution and intensities 

(a) General: the intensities prescribed in this paragraph must be provided by new equipment 

with each light cover and color filter in place. Intensities must be determined with the light 

source operating at a steady value equal to the average luminous output of the source at the 

normal operating voltage of the Airship's electricity supply. The light distribution and 

intensity of each position light must meet the requirements of subparagraph (b) of this 

paragraph.
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(b) Bow, forward, rearward and stern position lights: the light distribution and intensities of 

bow, forward, rearward and stern position lights must be expressed in terms of minimum 

intensities in the horizontal plane, minimum intensities in any vertical plane, and maximum 

intensities in overlapping beams, within dihedral angles F, L, R, and A, and must meet the 

following requirements: 

(1) Intensities in the horizontal plane: Each intensity in the horizontal plane (a plane 

containing the longitudinal axis of the Airship and perpendicular to the plane of symmetry 

of the Airship) must equal or exceed the values in HCC.1391. 

(2) Intensities in any vertical plane: Each intensity in any vertical plane (a plane 

perpendicular to the horizontal plane) must equal or exceed the appropriate value in 

HCC.1393, where I is the minimum intensity prescribed in HCC.1391 for the 

corresponding angles in the horizontal plane. 

(3) Intensities in overlaps between adjacent signals: no intensity in any overlap between 

adjacent signals may exceed the values in HCC.1395, except that higher intensities in 

overlaps may be used with main beam intensities substantially greater than the minimum 

specified in HCC.1391 and 1393, if the overlap intensities in relation to the main beam 

intensities do not adversely affect signal clarity. When the peak intensity of the forward 

and rearward position lights is more than 100 candles, the maximum overlap intensities 

between them may exceed the values in HCC.1395 if the overlap intensity in Area A is not 

more than 10% of peak position light intensity and the overlap intensity in Area B is not 

more than 2.5% of peak position light intensity. 

(c) Bow or stern position light installation: a single-position light may be installed in a 

position displaced laterally from the plane of symmetry of an Airship if: 

(1) The axis of the maximum cone of illumination is parallel to the flight path in level 

flight; 

(2) There is no obstruction aft of the light and between planes 70° to the right and left of 

the axis of maximum illumination. 

HCC.1391 Minimum intensities in the horizontal plane of bow, forward, rearward and 

stern position lights 

Each position light intensity must equal or exceed the applicable values in Table 10 of Appendix 

A. 

HCC.1393 Minimum intensities in any vertical plane of bow, forward, rearward and stern 

position lights 

Each position light intensity must equal or exceed the applicable values in Table 11 of Appendix 

A. 

HCC.1395 Maximum intensities in overlapping beams of bow and forward, forward and 

stern, respectively rearward and stern position light 

No position light intensity may exceed the applicable values in the Table 12 of Appendix A, 

except as provided in HCC.1389(b)(3). 
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HCC.1397 Color specifications

Each position light color must have the applicable International Commission on Illumination 

chromaticity coordinates as follows, where y0 is the y-coordinate of the Planckian radiator for the 

value of x considered

(a) Aviation red

y is not greater than 0.335; and

z is not greater than 0.002.

(b) Aviation green

x is not greater than 0.440 - 0.320 y;

x is not greater than y - 0.170; and

y is not less than 0.390 - 0.170 x.

(c) Aviation white

x is not less than 0.300 and not greater than 0.540;

y is not less than x - 0.040 or y0 - 0.010, whichever is the smaller; and

y is not greater than x + 0.020 nor 0.636 - 0.400 x.

HCC.1401 Anticollision light system

(a) General: the Airship must have an anticollision light system that:

(1) Consists of one or more approved anticollision lights located so that their light will not 

impair the flight crew members vision or detract from the conspicuity of the position 

lights;

(2) Is distributed in such a way that no aircraft crossing the Airships flight path might 

endeavor to fly between bow and stern lights.

(3) Meets the requirements of subparagraphs (b) through (f) of this paragraph. 

(b) Field of coverage: the system must consist of enough lights to illuminate the vital areas 

around the Airship, considering the physical configuration and flight characteristics of the 

Airship. The field of coverage must extend in each direction within at least 75° above and 75° 

below the horizontal plane of the Airship, except that there may be solid angles of obstructed 

visibility totaling not more than 0.5 steradians.

(c) Flashing characteristics: The arrangement of the system, that is, the number of light 

sources, beam width, speed of rotation, and other characteristics, must give an effective flash 

frequency of not less than 40, nor more than 100, cycles per minute. The effective flash 

frequency is the frequency at which the Airship's complete anticollision light system is 

observed from a distance, and applies to each sector of light including any overlaps that exist 

when the system consists of more than one light source. In overlaps, flash frequencies may 

exceed 100, but not 180 cycles per minute.

(d) Color: Each anticollision light must be either aviation red or aviation white and must meet 

the applicable requirements of HCC.1397.
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(e) Light intensity: the minimum light intensities in any vertical plane, measured with the red 

filter (if used) and expressed in terms of 'effective' intensities, must meet the requirements of 

subparagraph (f) of this paragraph. The following relation must be assumed:

where:

Ie effective intensity (candles),

I(t) instantaneous intensity as a function of time, 

t2-t1 flash time interval (seconds).

Normally, the maximum value of effective intensity is obtained when t2 and t1 are chosen so 

that the effective intensity is equal to the instantaneous intensity at t2 and t1. 

(f) Minimum effective intensities for anticollision lights: each anticollision light effective 

intensity must equal or exceed the applicable values in Table 13 of Appendix A.

SAFETY EQUIPMENT 

HCC.1411 General 

(a) Accessibility: required safety equipment to be used by the crew in an emergency must be 

readily accessible at all crew stations throughout the Airship: 

(b) Stowage provisions: Stowage provisions for required safety equipment must be furnished 

and must: 

(1) be arranged so that the equipment is directly accessible and its location obvious; and 

(2) protect the safety equipment from inadvertent damage caused by being subjected to the 

inertia loads specified in HCC.561. 

(c) Emergency exit descent device: The stowage provisions for the emergency exit descent 

device required by HCC.810 must be at the exits for which they are intended.

(d) Life rafts:

(1) The stowage provisions for the life rafts described in HCC.1415 must accommodate 

sufficient number of rafts for the maximum number of occupants for which certification is 

requested.

(2) Life rafts must be stowed near exits through which the rafts can be launched during an 

unplanned ditching.

(3) Rafts automatically or remotely released outside the Airship must be attached to the 

Airship by means of the static line prescribed in HCC.1415. 
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(4) The stowage provisions for each portable life raft must allow rapid detachment and 

removal of the raft for use at other than the intended exits.

(e) Long-range signaling device: the stowage provisions for the long-range signaling device 

required by HCC.1415 must be near an exit available during an unplanned ditching. 

(f) Life-preserver stowage provisions: the stowage provisions for life preservers described in 

HCC.1415 must accommodate one life preserver for each occupant: Each life preserver must 

be within easy reach. 

(g) Life line stowage provisions: there must be provisions to store the life lines. These 

provisions must allow one life line to be attached to each side of the passenger/crew 

compartments. 

(h) Survival equipment as specified by the operating rules will be included with the airship. 

Appropriate stowage, deployment instructions and continued airworthiness for such 

equipment will be provided.

HCC.1413 Safety belts 

(a) The rated strength of safety belts may not be less than that corresponding with the ultimate 

load factors specified in HCC.561 considering the dimensional characteristics of the belt 

installation for the specific seat or berth arrangement. 

(b) For safety belts for berths parallel to the longitudinal axis of the Airship, the forward load 

factor specified in HCC.561 need not be applied. 

(c) Each safety belt must be equipped with a metal to metal latching device. 

HCC.1414 Electrical bonding and protection against static electricity

(a) Electrical bonding and protection against static electricity must be designed to minimize 

accumulation of electrostatic charge that would cause—

(1) Human injury from electrical shock,

(2) Ignition of flammable vapors, or

(3) Interference with installed electrical/electronic equipment.

(b) Compliance with paragraph (a) of this section may be shown by—

(1) Bonding the components properly to the airframe; or

(2) Incorporating other acceptable means to dissipate the static charge so as not to 

endanger the airplane, personnel, or operation of the installed electrical/electronic systems.

HCC.1415 Ditching equipment 

(a) Ditching equipment used in Airships, required by the National Operating Rules, must meet 

the requirements of this paragraph. 

(b) Each life raft and each life preserver must be approved. In addition:

(1) Unless excess rafts of enough capacity are provided, the buoyancy and seating capacity 

beyond the rated capacity of the rafts must accommodate all occupants of the Airship in 

the event of a loss of one raft of the largest rated capacity; and 
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(2) Each raft must have a trailing line, and must have a static line designed to hold the raft 

near the Airship but to release it if the Airship becomes totally submerged. 

(c) Approved survival equipment must be attached to, or stored adjacent to, each life raft. 

(d) There must be an approved survival type emergency locator transmitter for use in one life 

raft.

(e) There must be life preservers or other approved flotation means within easy reach of each 

seated occupant and must be readily removable from the Airship. 

HCC.1417 Icing Detection 

A means must be provided for illuminating or otherwise determining the formation of ice on the 

parts that are critical from the standpoint of ice accumulation. Any illumination that is used must 

be of a type that will not cause glare or reflection that would handicap crew members in the 

performance of their duties. 

HCC.1419 Ice and snow protection 

(a) If certification for flight in icing conditions is desired, the Airship must be capable of safe 

operation in the continuous maximum, intermittent maximum, and takeoff maximum icing 

conditions of 14 CFR part 25 Appendix C Part 1. To establish that the Airship can operate 

within the continuous maximum, intermittent maximum and takeoff maximum condition:

(1) An analysis must be performed to establish that the ice protection for the various 

components of the Airship is adequate, taking into account the various Airship operational 

configurations and tests.

(2) To verify the ice protection analysis, to check for icing anomalies, and to demonstrate 

that the ice protection system and its components are effective, the Airship or its 

components must be flight tested in the various operational configurations, in natural 

measured atmospheric icing conditions, and as found necessary by adequate dry air flight 

tests, simulated icing tests, and/or laboratory tests.

(b) If certification for flight in snow conditions is desired, the Airship must be capable of safe 

operation in falling snow conditions. To establish that the Airship can operate in falling snow 

conditions:

(1) An analysis must be performed to establish that the snow protection for the various 

components of the Airship is adequate, taking into account the various Airship operational 

configurations and tests.

(2) To verify the snow protection analysis, to check for anomalies, and to demonstrate that 

the snow protection system and its components are effective, the Airship or its components 

must be flight tested in the various operational configurations, in falling snow conditions.

(c) If certification for flight in freezing drizzle and freezing rain conditions is desired, the 

Airship must be capable of safe operation in the freezing drizzle and freezing rain conditions 

of 14 CFR part 25 Appendix O. To establish that the Airship can operate in freezing drizzle 

and freezing rain conditions:
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(1) An analysis must be performed to establish that the ice protection for the various 

components of the Airship is adequate, taking into account the various Airship operational 

configurations and tests.

(2) To verify the ice protection analysis, to check for anomalies, and to demonstrate that 

the ice protection system and its components are effective, the Airship or its components 

must be flight tested in the various operational configurations, in freezing drizzle and 

freezing rain conditions, and as found necessary by adequate dry air flight tests, simulated 

icing tests, and/or laboratory tests.

HCC.1421 Megaphones 

If a megaphone is installed, a restraining means must be provided that is capable of restraining it 

when subjected to the ultimate inertia forces specified in HCC.561 (b)(2). 

HCC.1422 Lifting gas detector and alarm 

If a failure of a component could cause helium (lifting gas) to leak into a normally occupied area

(berth, flight deck, work station) a detector for the gas and an alarm must be installed in the 

compartment. This alarm must also be annunciated at the flight deck. In addition, a means to 

ventilate such compartments must be provided if contaminated with lifting gas.

MISCELLANEOUS EQUIPMENT 

HCC.1423 Public address system 

A public address system required by this HCC must: 

(a) Be powerable when the Airship is in flight or stopped on the ground, after the shutdown or 

failure of all engines and auxiliary power units, or the disconnection or failure of all power 

sources dependent on their continued operation, for: 

(1) A time duration of at least 30 minutes, including an aggregate time duration of at least 

10 minutes of announcements made by flight and cabin crew members, considering all 

other loads which may remain powered by the same source when all other power sources 

are inoperative; and 

(2) An additional time duration in its standby state appropriate or required for any other 

loads that are powered by the same source and that are essential to safety of flight or 

required during emergency conditions. 

(b) The system must be dual redundant and be capable of operation within 3 seconds from the 

time a microphone is removed from its stowage by a flight attendant at those stations in the 

passenger compartment from which its use is accessible. 

(c) Be intelligible at all locations where passengers might be expected including crew seats, 

lavatories, flight attendant seats and crew work stations. 

(d) Be designed so that no unused, unstowed microphone will render the system inoperative. 

(e) Be capable of functioning independently of any required crew member interphone system. 

(f) Be accessible for immediate use from each of two flight-crew member stations in the pilot 

compartment. 
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(g) For each required floor-level passenger emergency exit which has an adjacent flight 

attendant seat, have a microphone which is readily accessible to the seated flight attendant, 

except that one microphone may serve more than one exit, provided the proximity of the exits 

allows unassisted verbal communications between seated flight attendants. 

HCC.1431 Electronic equipment 

(a) In showing compliance with HCC.1309 (a) and (b) with respect to radio and electronic 

equipment and their installations, critical environmental conditions must be considered. 

(b) Radio and electronic equipment must be supplied with power under the requirements of 

HCC.1355 (c). 

(c) Radio and electronic equipment, controls and wiring must be installed so that operation of 

any one unit or system of units will not adversely affect the simultaneous operation of any 

other radio or electronic unit, or system of units, required by any applicable aviation rule or 

regulation. 

(d) Electronic equipment must be designed and installed such that it does not cause essential 

loads to become inoperative, as a result of electrical power supply transients or transients 

from other causes. 

HCC.1435 Hydraulic systems 

(a) Element design: each element of the hydraulic system must be designed to: 

(1) withstand the proof pressure without permanent deformation that would prevent it from 

performing its intended function, and the ultimate pressure without rupture. The proof and 

ultimate pressures are defined in terms of the design operating pressure (DOP) as follows:

(2) withstand, without deformation that would prevent it from performing its intended 

function, the design operating pressure in combination with limit structural loads that may 

be imposed;
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(3) withstand, without rupture, the design operating pressure multiplied by a factor of 1.5 

in combination with ultimate structural loads that can reasonably occur simultaneously; 

(4) Withstand the fatigue effects of all cyclic pressures, including transients, and associated 

externally induced loads, taking into account the consequences of element failure; and

(5) Perform as intended under all environmental conditions for which the Airship is 

certificated. 

(b) System design: each hydraulic system must: 

(1) have means located at a flight crew member station to indicate appropriate system 

parameters if, 

(i) it performs a function necessary for continued safe flight and landing; or 

(ii) in the event of hydraulic system malfunction, corrective action by the crew to ensure 

continued safe flight and landing is necessary; 

(2) have means to ensure that system pressures, including transient pressures and pressures 

from fluid volumetric changes in elements that are likely to remain closed long enough for 

such changes to occur, are within the design capabilities of each element, such that they 

meet the requirements defined in HCC.1435(a)(1) to HCC.1435(a)(5) inclusive; 

(3) have means to minimize the release of harmful or hazardous concentrations of 

hydraulic fluid or vapors into the crew and passenger compartments during flight;

(4) meet the applicable requirements of HCC.863, 1183, 1185 and 1189 if a flammable 

hydraulic fluid is used; and: 

(5) be designed to use any suitable hydraulic fluid specified by the Airship manufacturer, 

which must be identified by appropriate markings as required by HCC.1541.

(c) Tests: tests must be conducted on the hydraulic system(s), and/or subsystem(s) and

elements, except that analysis may be used in place of or to supplement testing where the 

analysis is shown to be reliable and appropriate. All internal and external influences must be 

taken into account to an extent necessary to evaluate their effects, and to assure reliable 

system and element functioning and integration. Failure or unacceptable deficiency of an 

element or system must be corrected and be sufficiently retested, where necessary.

(1) The system(s), subsystem(s), or elements must be subjected to performance, fatigue, 

and endurance tests representative of Airship ground and flight operations. 

(2) The complete system must be tested to determine proper functional performance and 

relation to other systems, including simulation of relevant failure conditions, and to 

support or validate element design. 

(3) The complete hydraulic system(s) must be functionally tested on the Airship in normal 

operation over the range of motion of all associated user systems. The test must be 

conducted at the relief pressure or 1.25 times the DOP if a system pressure relief device is 

not part of the system design. Clearances between hydraulic system elements and other 

systems or structural elements must remain adequate and there must be no detrimental 

mutual effects.
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HCC.1436 Pneumatic systems - high pressure 

(a) General: pneumatic systems which are powered by, and/or used for distributing or storing, 

air or nitrogen, must comply with the requirements of this paragraph if the product of system 

pressure times system volume amounts to 30 MPa m3 or more. 

(1) Compliance with HCC.1309 for pneumatic systems must be shown by functional tests, 

endurance tests and analysis. Any part of a pneumatic system which is an engine accessory 

must comply with the relevant requirements of HCC.1163. 

(2) No element of the pneumatic system which would be liable to cause hazardous effects 

by exploding if subject to a fire, may be mounted within an engine bay or other designated 

fire zone, or in the same compartment as a combustion heater.

(3) When the system is operating no hazardous blockage due to freezing must occur. If 

such blockage is liable to occur when the Airship is stationary on the ground, a pressure 

relieving device must be installed adjacent to each pressure source. 

(b) Design: each pneumatic system must be designed as follows: 

(1) Each element of the pneumatic system must be designed to withstand the loads due to 

the operating pressure, Pw, in the case of elements other than pressure vessels or to the 

limit pressure, PL, in the case of pressure vessels, in combination with limit structural loads 

which may be imposed without deformation that would prevent it from performing its 

intended function, and to withstand without rupture, the working or limit pressure loads 

multiplied by a factor of 1.5 in combination with ultimate structural loads that can 

reasonably occur simultaneously. 

(i) Pw: the working pressure is the maximum steady pressure in service acting on the 

element including the tolerances and possible pressure variations in normal operating 

modes but excluding transient pressures.

(ii) PL: the limit pressure is the anticipated maximum pressure in service acting on a 

pressure vessel, including the tolerances and possible pressure variations in normal 

operating modes but excluding transient pressures. 

(2) A means to indicate system pressure located at a flight-crew member station must be 

provided for each pneumatic system that: 

(i) performs a function that is essential for continued safe flight and landing; or

(ii) in the event of pneumatic system malfunction, requires corrective action by the crew 

to ensure continued safe flight and landing.

(3) There must be means to ensure that system pressures, including transient pressures and 

pressures from gas volumetric changes in components which are likely to remain closed 

long enough for such changes to occur: 

(i) will be within 90% to 110% of pump average discharge pressure at each pump outlet 

or at the outlet of the pump transient pressure dampening device, if provided; and 
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(ii) except as provided in sub-paragraph (b)(6) of this paragraph, will not exceed 125% 

of the design operating pressure, excluding pressure at the outlets specified in subparagraph (b)(3)(i) of this paragraph. Design operating pressure is the maximum steady 

operating pressure. The means used must be effective in preventing excessive pressures 

being generated during ground charging of the system. 

(4) Each pneumatic element must be installed and supported to prevent excessive 

vibration, abrasion, corrosion, and mechanical damage, and to withstand inertia loads. 

(5) Means for providing flexibility must be used to connect points in a pneumatic line 

between which relative motion or differential vibration exists.

(6) Transient pressure in a part of the system may exceed the limit specified in subparagraph (b)(3)(ii) of this paragraph if: 

(i) a survey of those transient pressures is conducted to determine their magnitude and 

frequency; and

(ii) based on the survey, the fatigue strength of that part of the system is substantiated 

by analysis or tests, or both. 

(iii) maintenance instructions are established. 

(7) The elements of the system must withstand the loads due to the pressure given in Table 

14 of Appendix A, for the proof condition without leakage or permanent distortion and for 

the ultimate condition without rupture. Temperature must be those corresponding to 

normal operating conditions. Where elements are constructed from materials other than 

aluminum alloy, tungum, or medium-strength steel, the Administrator may prescribe or 

agree other factors. The materials used should in all cases be resistant to deterioration 

arising from the environmental conditions of the installation, particularly the effects of 

vibration.

(8) Where any part of the system is subject to fluctuating or repeated external or internal 

loads, adequate allowance must be made for fatigue. 

(c) Tests:

(1) a complete pneumatic system must be static tested to show that it can withstand a 

pressure of 1.5 times the working pressure without a deformation of any part of the system 

that would prevent it from performing its intended function. Clearance between structural 

members and pneumatic system elements must be adequate and there must be no 

permanent detrimental deformation. For the purpose of this test, the pressure relief valve 

may be made inoperable to permit application of the required pressure. 

(2) The entire system or appropriate sub-systems must be tested in an Airship or in a 

mock-up installation to determine proper performance and proper relation to other Airship 

systems. The functional tests must include simulation of pneumatic system failure 

conditions. The tests must account for flight loads, ground loads, and pneumatic system 

working, limit and transient pressures expected during normal operation, but need not 

account for vibration loads or for loads due to temperature effects. Endurance tests must 

simulate the repeated complete flights that could be expected to occur in service. Elements 
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which fail during the tests must be modified in order to have the design deficiency 

corrected and, where necessary, must be sufficiently retested. Simulation of operating and 

environmental conditions must be completed on elements and appropriate portions of the 

pneumatic system to the extent necessary to evaluate the environmental effects.

(3) Parts, the failure of which will significantly lower the airworthiness or safe handling of 

the Airship must be proved by suitable testing, taking into account the most critical 

combination of pressures and temperatures which are applicable.

HCC.1437 Engine-driven accessories 

Engine-driven accessories essential to safe operation must be distributed among two or more 

engines so that the failure of any one engine will not impair safe operation through the 

malfunctioning of these accessories.

HCC.1438 Pneumatic systems- low pressure 

The following requirements apply to all pneumatic systems in the Airship except those systems 

dedicated to the pressurization of the envelope and ballonets: 

(a) pneumatic system elements must be burst pressure tested to 3 times and proof pressure 

tested to 1.5 times, the maximum normal operating pressure. 

(b) an analysis, or a combination of analysis and test may be substituted for any test required 

by subparagraph (a) of this paragraph if the Administrator finds it equivalent to the required 

test. 

HCC.1439 Protective breathing equipment 

(a) Protective breathing equipment must be installed for use of appropriate crew members. 

Such equipment must be located so as to be available for use in compartments accessible in 

flight. 

(b) For protective breathing equipment required by HCC.1439 (a) or by the National 

Operating Regulations the following apply: 

(1) The equipment must be designed to protect the appropriate crew members from smoke, 

carbon dioxide and other harmful gases while on flight deck duty or stations or while 

combating fires. 

(2) The equipment must include: 

(i) Masks covering the eyes, nose and mouth, or; 

(ii) Masks covering the nose and mouth, plus accessory equipment to cover the eyes 

(3) Equipment, including portable equipment, while in use must allow communication with 

other crew members. Equipment available at flight crew assigned duty stations must enable 

the flight crew to use radio equipment. 

(4) The part of the equipment protecting the eyes may not cause any appreciable adverse 

effect on vision and must allow corrective glasses to be worn. 

(5) Each dispensing equipment must supply protective oxygen for a minimum of 15 

minutes at a pressure altitude 8,000 ft with respiratory minute volume of 30 liters per 
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minute BTPD. The equipment and system must be designed to prevent any leakage to the 

inside of the mask and any significant increase in the oxygen content of the local ambient 

atmosphere.

HCC.1455 Draining of fluids subject to freezing

If fluids subject to freezing may be drained overboard in flight or during ground operation, the 

drains must be designed and located to prevent the formation of hazardous quantities of ice on 

the airship as a result of the drainage.

HCC.1457 Cockpit voice recorders 

(a) Each cockpit voice recorder required by the operating rules or HCC.1307 must be 

approved and must be installed so that it will record the following: 

(1) Voice communications transmitted from or received in the Airship by radio. 

(2) Voice communications of flight-crew members on the flight deck. 

(3) Voice communications of flight-crew members on the flight deck, using the Airship 

interphone system. 

(4) Voice or audio signals identifying navigation or approach aids introduced into a 

headset or speaker. 

(5) Voice communications of flight-crew members using the passenger loudspeaker 

system, if there is such a system and if the fourth channel is available in accordance with 

the requirements of subparagraph (c)(1)(iv)(B) of this paragraph.

(b) The recording requirements of subparagraph (a)(2) of this paragraph must be met by 

installing a cockpit-mounted area microphone, located in the best position for recording voice 

communications originating at the first and second pilot stations and voice communications of 

other crew members on the flight deck when directed to those stations. The microphone must 

be so located and, if necessary, the pre-amplifiers and filters of the recorder must be so 

adjusted or supplemented, that the intelligibility of the recorded communications is as high as 

practicable when recorded under flight cockpit noise conditions and played back. Repeated 

aural or visual playback of the record may be used in evaluating intelligibility. 

(c) Each cockpit voice recorder must be installed so that: 

(1) the part of the communication or audio signals specified in subparagraph (a) of this 

paragraph obtained from each of the following sources is recorded on a separate channel: 

(i) for the first channel, from each boom, mask, or hand-held microphone, headset, or 

speaker used at the first pilot station. 

(ii) for the second channel, from each boom, mask, or hand-held microphone, headset, 

or speaker used at the second pilot station. 

(iii) for the third channel, from the cockpit-mounted area microphone. 

(iv) for the fourth channel, from: 
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(A) each boom, mask, or hand-held microphone, headset or speaker used at the 

stations for the third and fourth crew members; or:

(B) if the stations specified in subparagraph (c)(1)(iv)(A) of this paragraph are not 

required or if the signal at such a station is picked up by another channel, each 

microphone on the flight deck that is used with the public address system if its 

signals are not picked up by another channel.

(2) As far as is practicable all sounds received by the microphones listed in subparagraphs 

(c)(1)(i),(ii) and (iv) of this paragraph are recorded without interruption irrespective of the 

position of the interphone-transmitter key switch. The design must ensure that sidetone for 

the flight crew is produced only when the interphone, public address system or radio 

transmitters are in use. 

(d) Each cockpit voice recorder must be installed so that: 

(1) It receives its electric power from the bus that provides the maximum reliability for 

operation without jeopardizing service to essential or emergency loads; 

(2) There is an automatic means to stop simultaneously the recorder and prevent each 

erasure feature from functioning, within 10 minutes after crash impact; and 

(3) There is an aural or visual means for pre-flight checking of the recorder for proper 

operation. 

(e) The record container must be located and mounted to minimize the probability of rupture 

of the container as a result of crash impact and consequent heat damage to the record from fire

(f) If the cockpit voice recorder has a bulk erasure device, the installation must be designed to 

minimize the probability of inadvertent operation and actuation of the device during crash 

impact. 

(g) Each recorder container must: 

(1) Be either bright orange or bright yellow; 

(2) Have reflective tape affixed to its external surface to facilitate its location under water; 

and 

(3) Have an underwater locating device, when required by the operating rules, on or 

adjacent to the container which is secured in such a manner that they are not likely to be 

separated during crash impact. 

HCC.1459 Flight recorders 

(a) Each flight recorder required by the operating rules or HCC.1307 must be installed so that: 

(1) It is supplied with airspeed, altitude, and directional data obtained from sources that 

meet the accuracy requirements of HCC.1323, 1325 and 1327, as appropriate; 

(2) The vertical acceleration sensor is rigidly attached and located longitudinally within the 

approved center of gravity limits of the Airship. 
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(3) It receives its electrical power from the bus that provides the maximum reliability for 

operation of the flight recorder without jeopardizing service to essential or emergency 

loads; 

(4) There is an aural or visual means for preflight checking of the recorder for proper 

recording of data in the storage medium; 

(5) Except for recorders powered solely by the engine-driven electrical generator system, 

there is an automatic means to simultaneously stop a recorder that has a data erasure 

feature and prevent each erasure feature from functioning, within 10 minutes after crash 

impact; and: 

(6) There is a means to record data from which the time of each radio transmission either 

to or from ATC can be determined. 

(b) Each non-ejectable record container must be located and mounted so as to minimize the 

probability of container rupture resulting from crash impact and subsequent damage to the 

record from fire.

(c) A correlation must be established between the flight recorder readings of airspeed, 

altitude, and heading and the corresponding readings (taking into account correction factors) 

of the first pilot's instruments. The correlation must cover the airspeed range over which the 

Airship is to be operated, the range of altitude to which the Airship is limited, and 360o of 

heading. Correlation may be established on the ground as appropriate. 

(d) Each recorder container must: 

(1) Be either bright orange or bright yellow; 

(2) Have reflective tape affixed to its external surface to facilitate its location under water; 

(3) Have an underwater locating device, when required by the operating rules of this 

chapter, on or adjacent to the container which is secured in such a manner that they are not 

likely to be separated during crash impact. 

(e) Any novel or unique design or operational characteristics of the Airship shall be evaluated 

to determine if any dedicated parameters must be recorded on flight recorders in addition to or 

in place of existing requirements. 

HCC.1461 Equipment containing high energy rotors 

(a) Equipment containing high energy rotors must meet subparagraph (b), (c), or (d) of this 

paragraph. 

(b) High energy rotors contained in equipment must be able to withstand damage caused by 

malfunctions, vibration, abnormal speeds, and abnormal temperatures. In addition: 

(1) Auxiliary rotor cases must be able to contain damage caused by the failure of high 

energy rotor blades; 

(2) Equipment control devices, systems, and instrumentation must ensure, to a reasonable 

extent, that no operating limitations affecting the integrity of high energy rotors will be 

exceeded in service. 
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(c) It must be shown by test that equipment containing high energy rotors can contain any 

failure of a high energy rotor that occurs at the highest speed obtainable with the normal 

speed control devices inoperative. 

(d) Equipment containing high energy rotors must be located where rotor failure will neither 

endanger the occupants nor adversely affect continued safe flight. 

HCC.1499 Domestic services and appliances 

(a) Domestic appliances must be so designed and installed that in the event of failures of the 

electrical supply or control system the requirements of HCC.1309 will be satisfied. 

(b) The installation of galleys and cooking appliances must be such as to minimize the risk of 

fire.

(c) Domestic appliances, particularly those in galley areas must be so installed or protected as 

to prevent damage or contamination of other equipment or systems from fluids or vapors 

which may be present during normal operation or as a result of spillage, where such damage 

or contamination may hazard the Airship.

(d) All electric domestic appliances must be suitably grounded. 
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Subpart G - Operating Limitations and Information 

GENERAL 

HCC.1501 General 

(a) Each operating limitation specified in HCC.1505 through 1533 and other limitations and 

information necessary for safe operation must be established. 

(b) The operating limitations and other information necessary for safe operation must be made 

available to the crew members as prescribed in HCC.1541 through 1601. 

OPERATING LIMITATIONS 

HCC.1503 Airspeed limitations: general 

When airspeed limitations are a function of mass, mass distribution, static heaviness, altitude, 

limitations corresponding to each critical combination of these factors must be published. 

HCC.1505 Maximum operating speed limits 

The maximum operating limit speed, VMO, is a speed that may not be deliberately exceeded in 

any regime of flight (climb, cruise, or descent), unless a higher speed is authorized for flight test 

or pilot training operations. VMO must be established so that it is not greater than the design 

maximum level flight airspeed VH and so that it is sufficiently below VCD, to make it highly 

improbable that the latter speed will be inadvertently exceeded in operations.

HCC.1515 ACLS speeds 

(a) The maximum ACLS operating speed, VLO, may not exceed the speed determined under 

HCC.729 or by flight characteristics. 

(b) The established ACLS extended speed VLE may not exceed the speed at which it is safe to 

fly with the ACLS secured in the fully extended position 

HCC.1516 Other speed limitations 

Any other limitation associated with speed must be established. 

HCC.1519 Mass and center of gravity and mass distribution 

The mass/static lift and center of gravity/static lift limitations determined under HCC.23 must be 

established as operating limitations. This includes the maximum takeoff mass, maximum landing 

mass and maximum permissible static heaviness and static lightness. The distribution of mass, 

static lift and useful load must be established as operating limitations. If a control car is used, its 

maximum mass must be determined. The maximum mass of all items supported by the keel or 

car structure, including cargo, passengers, crew, fuel and ballast must be determined for each 

location. A procedure for monitoring and recording the load distribution must be established and 

satisfy HCC.1583(c)(4). 

HCC.1521 Powerplant limitations 

(a) General: the powerplant limitations prescribed in this paragraph must be established so 

that they do not exceed the corresponding limits for which the engines or propellers are either 

approved or type certificated and do not exceed the values on which compliance with any 

other requirement of this HCC is based. 
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(b) Takeoff operation with relation to augmented or unaugmented operation as applicable: the 

powerplant takeoff operation must be limited by: 

(1) the maximum rotational speed (rpm.); 

(2) the maximum allowable manifold pressure (for reciprocating, altitude engines; not 

required for diesel engines);

(3) the maximum allowable gas temperature (for turbine engines); 

(4) horsepower, torque or thrust (for turbine engines) 

(5) the time limit for the use of the Takeoff operation corresponding to the limitations 

established in subparagraphs (1) through (4) of this paragraph; 

(6) the maximum allowable cylinder head, liquid coolant and oil temperatures (as 

applicable). 

(c) Continuous operation with relation to augmented or unaugmented operation as applicable: 

the continuous operation must be limited by

(1) the maximum rotational speed; 

(2) the maximum allowable manifold pressure (for reciprocating, altitude engines; not 

required for diesel engines); 

(3) the maximum allowable gas temperature (for turbine engines);

(4) horsepower, torque or thrust (for turbine engines) 

(5) the maximum allowable cylinder head (as applicable), oil and liquid coolant 

temperatures. 

(d) Fuel grade or designation: the minimum fuel grade (for reciprocating engines) or fuel 

designation or specification (for diesel and turbine engines) must be established so that it is 

not less than that required for the operation of the engines within the limitations of paragraphs 

(b) and (c) of this paragraph. 

(e) Any other parameter for which a limitation has been established as part of the engine type 

certificate except that a limitation need not be established for a parameter that cannot be 

exceeded during normal operation due to the design of the installation or to another 

established limitation. 

(f) Transmission (for thrusters): the transmission operation must be limited by: 

(1) the maximum rotational speed, which may not be greater than -

(i) the maximum value determined by the design; or 

(ii) the maximum value shown during the type tests; 

(2) the maximum allowable power or torque for each engine, considering the power input 

limitations of the transmission with all engines operating; 

(3) the time limit for the use of the power corresponding to the limitations established in 

subparagraphs (b) (1) and (2) of this paragraph; and 
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(4) the maximum allowable transmission oil temperatures. 

(g) Ambient temperature limitations (including limitations for winterization installations if 

applicable) must be established as the maximum ambient atmospheric temperature at which 

compliance with the cooling provisions of HCC.1041 to 1045 is shown.

HCC.1522 Auxiliary power unit limitations 

If an auxiliary power unit (APU) is installed in the Airship, limitations established for the APU, 

including categories of operation, must be specified as operating limitations for the Airship. 

HCC.1523 Minimum flight crew 

The minimum flight crew must be established so that it is sufficient for safe operation 

considering: 

(a) the workload on individual crew members; 

(b) the accessibility and ease of operation of necessary controls by the appropriate crew 

members; 

(c) the kinds of operation authorized under HCC.1525;

(d) appropriate crew coordination for all tasks where several crew members are incorporated 

in the operation: 

(e) adequate supervision/control when the Airship is parked. 

HCC.1524 Systems and equipment limitations 

All limitations applicable to functional equipment and systems installations, and which are 

considered necessary for safe operation, must be established. 

HCC.1525 Kinds of operation 

The kinds of operation to which the Airship is limited are established by the category in which it 

is eligible for certification and by the installed equipment. 

HCC.1526 Maximum rates of climb and descent 

The maximum rates of climb and descent determined under HCC.65(b) must be established. 

HCC.1527 Ambient air temperature and operating altitude 

The extremes of the ambient air temperature and operating altitude for which operation is 

allowed, as limited by flight, structural, powerplant, functional, or equipment characteristics, 

must be established. 

HCC.1528 Envelope, lifting gas and ballonet pressures 

Operating pressure differential limitations for the envelope and ballonets, as limited by flight, 

structural and functional requirements, must be established. 

HCC.1529 Instructions for continued airworthiness 

The applicant must prepare Instructions for Continued Airworthiness in accordance with 14 CFR 

part 25 Appendix H that are acceptable to the Administrator. The instructions may be incomplete 

at type certification if a program exists to ensure their completion prior to delivery of the first 

airship or issuance of a standard certificate of airworthiness, whichever occurs later.
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HCC.1530 Engine or propeller vectoring 

The maximum engine vectoring angles, to which operation is allowed, as limited by flight, 

structural, powerplant, and functional requirements, must be established. 

HCC.1533 Additional operating limits 

Maximum passenger/location configuration: the maximum number of passengers and their 

location must be established, considering evacuation provisions (see HCC.803). 

MARKINGS AND PLACARDS 

HCC.1541 General 

(a) The Airship must contain 

(1) The specified markings and placards; 

(2) Any additional information, instrument markings, and placards required for the safe 

operation of the Airship. 

(b) Each marking and placard prescribed in subparagraph (a) of this paragraph 

(1) Must be displayed in a conspicuous place; 

(2) May not be easily erased, disfigured, or obscured. 

HCC.1543 Instrument markings: general 

For each instrument: 

(a) when markings are on the cover glass of the instrument, there must be means to maintain 

the correct alignment of the glass cover with the face of the dial; 

(b) each arc and line must be wide enough and located to be clearly visible to the pilot; 

HCC.1544 Operating pressure limitations 

The maximum operating pressures must be indicated on each gauge for the envelope or ballonets 

in pressure Airships.

HCC.1545 Airspeed limitation information 

The airspeed limitations required by HCC.1583 (a) must be easily read and understood by the 

flight crew.

HCC.1547 Magnetic direction indicator 

(a) A placard meeting the requirements of this paragraph must be installed on or near the 

magnetic direction indicator. 

(b) The placard must show the calibration of the instruments in level flight with the engines 

operating. 

(c) The placard must state whether the calibration was made with radio receivers on or off. 

(d) Each calibration reading must be in terms of magnetic heading in not more than 30° 

increments. 
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(e) If a magnetic nonstabilized direction indicator can have a deviation of more than 10° 

caused by the operation of electrical equipment, the placard must state which electrical loads, 

or combination of loads, would cause a deviation of more than 10° when turned on.

HCC.1549 Powerplant and APU instruments 

For each required powerplant instrument, as appropriate to the type of instrument 

(a) Each maximum and, if applicable, minimum safe operating limit must be marked with a 

red radial or a red line; 

(b) Each normal operating range must be marked with a green arc or green line, not extending 

beyond the maximum and minimum safe limits; 

(c) Each takeoff and precautionary range must be marked with a yellow arc or a yellow line; 

(d) Each engine, propeller speed range, vectoring angle and speed and bow/tail thruster 

deflection that is restricted because of excessive vibration stresses must be marked with red 

arcs or red lines. 

HCC.1551 Oil quantity indicator 

Each oil quantity indicator must be marked in sufficient increments to indicate readily and 

accurately the quantity of oil. 

HCC.1553 Fuel quantity indicator 

If the unusable fuel supply for any tank exceeds one gallon (4 liters) or 5% of the tank capacity, 

whichever is greater, a red arc must be marked on its indicator extending from the calibrated zero 

reading to the lowest reading obtainable in level flight.

HCC.1555 Control markings 

(a) Each cockpit control, other than primary flight controls and controls, the function of which 

is obvious, must be plainly marked as to its function and method of operation. 

(b) Each secondary control must be suitably marked. 

(c) For powerplant fuel controls 

(1) Each fuel tank selector control must be marked to indicate the position corresponding 

to each tank and to each existing cross feed position; 

(2) If safe operation requires the use of any tanks in a specific sequence, that sequence 

must be marked on or near the selector for those tanks; 

(3) The conditions under which the full amount of usable fuel in any restricted usage fuel 

tank can safely be used must be stated on a placard adjacent to the selector valve for that 

tank; 

(4) Each valve control for any engine must be marked to indicate the position 

corresponding to each engine controlled. 

(d) Usable fuel capacity must be marked as follows. 

(1) For fuel systems having no selector controls, the usable fuel capacity of the system 

must be indicated at the fuel quantity indicator. 
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(2) For fuel systems having selector controls, the usable fuel capacity available at each 

selector control position must be indicated near the selector control. 

(e) For accessory, auxiliary, and emergency controls 

(1) If retractable ACLS is used, the indicator required by HCC.729(e) must be marked so 

that the pilot can, at any time, ascertain that the ACLS pads are fully deployed or retracted.

(2) Each emergency control must be red and must be marked with its method of operation. 

HCC.1557 Miscellaneous markings and placards 

(a) Throughout the ship, placarding shall ensure safe mass distribution. The following 

locations must have placards stating any limitations on contents, including mass, that are

necessary under the loading requirements: 

(1) each passenger compartment 

(2) each location, where occupants are likely to gather 

(3) each baggage and cargo compartments 

(4) each ballast location 

(b) Seats: if the maximum allowable mass to be carried in a seat is less than 215 lb (98 kg), a 

placard stating the lesser mass must be permanently attached to the seat structure. 

(c) Fuel, coolant and oil filler openings: the following apply. 

(1) Fuel filler openings must be marked at or near the filler cover with 

(i)The wording of the required fuel (e.g. "Avgas", "Diesel-Engine Oil" or "Jet Fuel"); 

and 

(ii) The minimum fuel grade or references to the Airship Flight Manual (AFM) for 

permissible fuel designations. 

(iii) For pressure fueling systems, the maximum permissible fueling supply pressure and 

the maximum permissible defueling pressure.

(iv) For diesel engine-powered airships-

(A) The words “Jet Fuel”; and 

(B) The permissibly fuel designations, or references to the Airship Flight Manual 

(AFM) for permissible fuel designations.

(C) A warning placard or note that states the following or similar: “Warning----this 

airship is equipped with an aircraft diesel engine; service with approved fuels only.” 

Color of this warning placard should be back and white.

(2) Oil filler openings must be marked at or near the filler cover with the word 'Oil', the oil 

capacity, and the approved grade and specification of oil. 
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(3) If placards and markings at the fuel or oil opening include tank capacity, the capacity 

shall be specified in U.S. gallons and liters. 

(d) Coolant filler openings must be marked at or near the filler cover with the word "Coolant". 

(e) Augmentation fluid filler openings must be marked at or near the filler cover to identify 

the required fluid.

HCC.1559 Operating limitations placard 

There must be a placard in clear view of the pilot that specifies the kind of operations (such as 

VFR, IFR, day or night) and meteorological conditions (such as icing conditions) to which the 

operation of the Airship is limited, or from which it is prohibited, by the equipment installed. 

HCC.1561 Safety equipment 

(a) Each safety equipment control to be operated by the crew in emergency, such as controls 

for automatic liferaft releases, must be plainly marked as to its method of operation.

(b) Each location, such as a locker or compartment, that carries any fire extinguishing, 

signaling, or other life saving equipment must be marked accordingly.

(c) Stowage provisions for required emergency equipment must be conspicuously marked to 

identify the contents and facilitate the easy removal of the equipment.

(d) Each liferaft must have obviously marked operating instructions.

(e) Approved survival equipment must be marked for identification and method of operation.

HCC.1563 Airspeed/ Altitude/ Attitude placard 

There must be placards for maximum airspeed, altitude and attitude in clear view of the pilot and 

as close as practicable to the applicable indicators. 

AIRSHIP FLIGHT MANUAL 

HCC.1581 General 

(a) Furnishing information: an Airship Flight Manual and an Airship Ground Handling 

Manual, for ground handling procedures, must be furnished with each Airship, and they must 

contain the following. 

(1) Information required by HCC.1583 through 1589; 

(2) Other information that is necessary for safe operation because of design, operating, or 

handling characteristics. 

(b) Approved information: 

(1) Each part of the Airship Flight Manual containing information prescribed in HCC.1583 

through 1589 must be approved, segregated, identified, and clearly distinguished from 

each unapproved part of that manual. 

(2) Reserved

(3) Each page of the Airship Flight Manual containing information prescribed in this 

paragraph must be of a type that is not easily erased, disfigured, or misplaced, and is 
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capable of being inserted in a manual provided for the product, or in a folder, or in any 

other permanent binder. 

(c) Each Airship Flight Manual must include a table of contents if the complexity of the 

manual indicates a need for it. 

HCC.1583 Operating limitations 

(a) Airspeed limitations: the following information must be furnished. 

(1) The maximum operating limit speed, VMO, and a statement that this speed limit may not 

be deliberately exceeded in any regime of flight (climb, cruise, or descent) unless a higher 

speed is authorized for flight test or pilot training;

(2) The ACLS operating speed or speeds, if applicable, and a statement explaining the 

speeds as defined in HCC.1515. 

(3) Reserved

(4) The maximum speed VRA for flight in rough air 

(b) Powerplant limitations: the following information must be furnished. 

(1) Limitations required by HCC.1521 and 1522; 

(2) Explanation of the limitations, when appropriate; 

(3) Information necessary for marking the instruments required by HCC.1549 through 

1553. 

(c) Mass/Lift: the Airship Flight Manual must include the following mass/lift limitations. 

(1) Maximum mass/lift (takeoff); 

(2) Maximum landing mass/lift; 

(3) Maximum permissible static heaviness and static lightness; 

(4) Maximum useful load and distribution; 

(5) Maximum baggage compartment mass.

(6) Maximum freight loading unit mass (maximum freight inclusive) 

(d) Center of gravity: the established center of gravity limits must be furnished. 

(e) Flight crew: the minimum crew required must be stated and if more than one is required 

for safety, the number and functions of the minimum flight crew must be furnished. 

(f) Types of operation: the types of operation (such as VFR, IFR, day, or night) and the 

meteorological conditions under which the Airship may or may not be used, must be 

furnished. Installed equipment that affects any operating limitation must be listed and 

identified with its operational function. 

(1) The Airship Flight Manual will include instructions for operating the airship when the 

envelope is wet, and when the airship may have additional weight due to envelope having 

attached ice, snow and or frost. The instructions will consider the effects on weight and 

balance and on aerodynamic lift and control.
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(g) Maximum passenger configuration: the maximum number of passengers and their required 

location (plus safety precautions) during takeoff and landing must be furnished. 

(h) Envelope pressure: the minimum and maximum envelope and (when installed) ballonet 

pressures must be furnished. 

(i) Maximum rates of ascent and descent: the maximum rates of ascent and descent must be 

furnished. 

(j) Maneuvers: the maximum pitch angles and turning rates for the Airship must be furnished 

in relation to flying speed.

(k) Placards: any placards which are required by HCC.1541 through 1563 must be reproduced 

in the Airship Flight Manual together with a written description of the appropriate locations of 

each on the Airship. 

(l) Snow loads: the maximum loads of snow or ice and information for measuring these loads 

must be established and published in the Airship Flight Manual and Airship Ground Handling 

Manual. 

(m) Types of surface: a statement of the types of surface of the landing fields on which 

operation may be conducted. This will include operations on water and or ice if such 

operations are requested and approved.

(n) System and equipment limitations established must be furnished. 

(o) The extremes of the ambient air temperatures and operating altitudes must be furnished. 

HCC.1585 Operating procedures 

(a) For each Airship, information concerning normal and emergency procedures and other 

pertinent information necessary for safe operation must be furnished, including 

(1) The recommended climb speed and any variation with altitude; 

(2) The recommended takeoff and climb profiles including use of auxiliary thrust, lift, and 

trim controls, and power management for normal takeoff and climb as well as for short 

field operations, if different; 

(3) The recommended approach and landing speeds and profiles including use of auxiliary 

thrust, lift and trim controls and power management for normal approach and landing as 

well as for short field operations, if different; 

(4) Landing and loading interruption information: 

(i) the recommended balked landing climb airspeeds and procedures for transitioning 

from approach and landing to the balked landing climb; 

(ii) the recommended procedure for interrupted cargo or ballast loading based on the 

requirements of HCC.80(c); 

(5) The recommended procedures for transitioning from powered flight to nonpowered 

flight mode and associated descent and landing procedures for the nonpowered flight 

mode.
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(6) Operational procedures for maintaining lifting gas pressures based on the requirements 

of HCC.887; 

(7) Instructions covering the use of control system locks, when used; 

(8) Flammable fluid fire protection instructions and procedures based on the requirements 

of HCC.863; 

(9) The recommended procedures for starting and stopping engines as required by 

HCC.903(e) and (f); 

(10) Ditching instructions and procedures (including the procedures based on the 

requirements of HCC.807(b), HCC.1411 and 1415); 

(11) Instructions and procedures covering the use of ice protection equipment required by 

HCC.1419; 

(12) If required, any special procedures for transitioning from statically heavy to statically 

light while underway.

(13) The recommended ground handling, parking, and mooring procedures required by 

HCC.255 (these procedures must reflect the design capabilities of the Airship as required 

by HCC.481). Description in a separate manual is optional; 

(14) Reserved 

(15) Operational procedures covering fuel jettisoning based on the requirements of 

HCC.1001;

(16) Operational procedures covering the emergency evacuation based on the requirements 

of HCC.803 and HCC.883 (h).

(17) The maximum demonstrated values of wind for parking, mooring, takeoff and landing 

and procedures and information pertinent to operations in wind. 

(b) The following information and procedures must also be included: 

(1) normal and emergency procedures for single engine out operations and all engine out 

operations; 

(2) information and procedures for obtaining the best climb and descent performance must 

be furnished for various configurations of the Airship for the following conditions:

(i) Most critical engine inoperative 

(ii) Most critical auxiliary or vectored thrust systems inoperative 

(3) Procedures for takeoff determined in accordance with HCC.51; 

(4) Information identifying each operating condition in which the fuel system 

independence prescribed in HCC.953 is necessary for safety must be furnished, together 

with instructions for placing the fuel system in a configuration used to show compliance 

with that paragraph. 

(c) For each Airship showing compliance with HCC.1353(c)(6), the operating procedures for 

disconnecting the battery from its charging source must be furnished. 
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(d) If the unusable fuel quantity in any tank exceeds 5% of the tank capacity, or one gallon (4 

liters), whichever is greater, information must be furnished which indicates that when the fuel 

quantity indicator reads 'zero' in level flight, any fuel remaining in the fuel tank cannot be 

used safely in flight.

(e) Information on the total quantity of usable fuel for each fuel tank must be furnished. 

(f) In addition, the procedures for restarting any engine in flight, including the effects of 

altitude, must be published in the Airship Flight Manual.

HCC.1587 Performance information 

(a) For each Airship, if applicable, the following information must be furnished: 

(1) Any loss of altitude more than 100 ft (30 m), or any pitch angle greater than 30°, 

occurring during the recovery prescribed in HCC.77 and 203; 

(2) The conditions under which the full amount of usable fuel in each tank can safely be 

used;

(3) The takeoff distance determined under HCC.51, the airspeed at the 50 ft (15 m) height, 

the Airship configuration (if pertinent), the kind of surface in the tests, use of flight path

control devices and use of the ACLS retraction system (if installed); 

(4) The landing distance determined under HCC.75, the Airship configuration (if 

pertinent), the use of bow or tail thrusters (if installed) and the kind of surface used in the 

tests; 

(5) The steady rate or gradient of climb determined under HCC.65 and 67, the airspeed, 

power, and the Airship configuration; 

(6) The calculated approximate effect on takeoff distance (subparagraph (a)(3) of this 

paragraph), landing distance (subparagraph (a)(4) of this paragraph), and steady rates of 

climb (subparagraph (a)(5) of this paragraph), of variations in 

(i) Altitude from sea level to maximum design takeoff altitude; 

(ii) Temperature at these altitudes from 60°F (33°C) below standard to 40°F (22°C) 

above standard; 

(iii) Relative humidity at these altitudes from 20% to 100%; 

(iv) Lifting gas purity. 

(7) For reciprocating engine-powered Airships, the maximum atmospheric temperature at 

which compliance with the cooling provisions of HCC.1041 through 1063 is shown; 

(8) Maximum speed for various static conditions and turbulence; 

(9) Maximum airspeed, pitch and yaw angle and all other relevant data, established under 

HCC.80, allowed during cargo exchange operations 

(10) Maximum allowable wind and cross wind speeds during takeoff and landing. 

(11) Pressure height, or maximum allowable altitude, in relation to ballonet fullness.
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(12) The techniques, associated airspeeds, and rates of ascent and descent for vertical 

takeoffs and landings for each airship configuration.

(13) The hover performance as determined under HCC.49 and the maximum static 

heaviness for each altitude, temperature, and wind conditions at which the airship can 

safely hover.

(b) The following additional information must be furnished. 

(1) The best rate of climb speed with the most critical engine inoperative; 

(2) The speed used in showing compliance with the cooling and climb requirements of 

HCC.1045 (e)(4), if this speed is greater that the best rate of climb speed with the critical 

engine inoperative; 

(3) The steady rate or gradient of climb determined under HCC.67 and the airspeed, power, 

and airship configuration;

(4) The calculated approximate effect on the climb performance determined under HCC.67 

of variations in: 

(i) Altitude from sea level to maximum design altitude; 

(ii) Temperature at these altitudes from 60°F (33°C) below standard to 40°F (22°C) 

above standard; 

(iii) Relative humidity at these altitudes from 20% to 100%; 

(iv) Lifting gas purity; 

(v) Effects on performance with various numbers of engines inoperative including a 

single operating engine. 

(vi) Limits for vectored thrust positions and power settings required for takeoff and 

landings for various static conditions. 

(c) The Airship Flight Manual must contain at least the following performance information. 

(1) Sufficient information so that the takeoff mass limits specified in HCC.1583 can be 

determined for all temperatures and altitudes within the operational limitations selected for 

the product; 

(2) The conditions under which the performance information was obtained including the 

airspeed at the 50 ft height used to determine the landing distance as required by HCC.75; 

(3) The performance information (determined by extrapolation and computed for the range 

of mass between the maximum landing and maximum takeoff mass) for

(i) Climb in the landing configuration as determined by HCC.77; and:

(ii) Landing distance as determined by HCC.75;
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(4) Procedures information established in accordance with the limitations and other 

information for safe operation of the Airship in the form of recommended procedures;

(5) An explanation of significant or unusual flight and ground handling characteristics of 

the Airship. 

HCC.1589 Loading information 

The following loading information must be furnished: 

(a) the mass and location of each item of equipment included in the empty mass as determined 

under HCC.29 

(b) appropriate loading instructions for each possible loading condition between the maximum 

and minimum mass determined under HCC.25 that can result in a center of gravity 

distribution beyond: 

(1) The extremes selected for the product; or 

(2) The extremes within which the structure is proven; or 

(3) The extremes within which compliance with each functional requirement is shown. 

(c) Loading information must include external or sling loads if approved.

(d) Loading information must include ballast if approved.

HYBRID FUNCTION AND RELIABILITY TESTING

HCC.2135 Function and reliability testing

Function and reliability testing is required and shall be no less than the minimum specified by 

CFR 14 part 21.35(f). Flight profiles and the amount of testing shall be agreed to by the 

Administrator who may require specific flight profiles or more testing than the minimum as 

warranted by the complexity and novel features of the airship.
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Subpart J - Powerplant (Auxiliary Power Unit (APU))

GENERAL 

HCC.J901 Installation 

(a) For the purpose of this criteria, Airship APU installations include each component that: 

(1) Reserved

(2) Affects the safety and control of the major APU(s); or: 

(3) Affects the safety of the major APUs between normal inspections or overhauls. 

(b) For each APU: 

(1) The installation must comply with: 

(i) The installation instructions provided under 14 CFR part 33.5 or equivalent 

instructions; and: 

(ii) The applicable provisions of this Subpart. 

(2) The components of the installation must be constructed, arranged, and installed so as to 

ensure their continued safe operation between normal inspections or overhauls. 

(3) The installation must be accessible for necessary inspections and maintenance; and 

(4) The major components of the installation must be electrically bonded to the other parts 

of the Airship. 

(c) The APU installation must comply with HCC.1309. 

(d) Reserved

(e) The satisfactory functioning of the APU must be demonstrated by ground and flight tests 

over the range of operating conditions for which certification is required and must include 

tests under hot climatic conditions, unless equivalent evidence cam be produced. 

HCC.J903 Engines 

(a) Engine type certification: 

(1) Each engine must be approved and have a type certificate.

(2) Each turbine engine not certificated to 14 CFR part 33 must be shown to comply with 

14 CFR part 33 or be shown to have a foreign object ingestion service history in similar 

installation locations which have not resulted in any unsafe condition or that the particular 

installation excludes ingestion. 

(b) Engine isolation: The powerplants must be arranged and isolated from each other to allow 

operation, in at least one configuration, so that the failure or malfunction of any engine, or the 

failure or malfunction (including destruction by fire in the engine compartment) of any system 

that can affect an engine (other than a fuel tank, if only one fuel tank for two engines is 

installed), will not: 
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(1) Prevent the continued safe operation of the remaining engines; or 

(2) Require immediate action by a crew member for continued safe operation of the 

remaining engines. 

(c) Reserved

(d) Turbine engine installations: For turbine engine installations 

(1) Design precautions must be taken to minimize the hazards to the Airship in the event of 

an engine-rotor failure or a fire originating inside the engine which burns through the 

engine casing;

(2) The powerplant systems associated with engine control devices, systems, and 

instrumentation must be designed to give reasonable assurance that those operating 

limitations that adversely affect turbine rotor structural integrity will not be exceeded in 

service. 

(e) Restart capability. 

(1) Means to restart any engine in flight must be provided. 

(2) An altitude and airspeed envelope must be established for the Airship for in-flight 

engine restarting, and each installed engine must have a restart capability within that 

envelope. 

(f) Starting and stopping (piston engine): the design of the installation must be such that risk 

of fire or mechanical damage to the engine or Airship, as a result of starting is reduced to a 

minimum. Any techniques and associated limitations for engine starting must be established 

and published in the Airship Flight Manual, approved manual material, or applicable 

operating placards. Means must be provided for stopping and restarting each engine in flight. 

In addition the following apply: 

(1) Each component of the stopping system on the engine side of the firewall that might be 

exposed to fire must be at least fire resistant. 

HCC.J907 Vibration 

(a) Reserved

(b) Engine vibration: each engine must be installed to prevent the harmful vibration of any 

part of the engine or Airship. 

HCC.J908 Cooling fans

For cooling fans that are a part of an APU installation the following apply: 

(a) For cooling fans installed in Airships, it must be shown that a fan blade failure will not 

prevent continued safe flight either because of damage caused by the failed blade or loss of 

cooling air. 

(b) Fatigue evaluation: Unless a fatigue evaluation under HCC.571 is conducted, it must be 

shown that cooling fan blades are not operating at resonant conditions within the operating 

limits of the Airship. 
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HCC.J909 Turbochargers 

(a) Each turbocharger must be approved under the engine type certificate, or it must be shown 

that the turbocharger system 

(1) Can withstand, without defect, an endurance test of 150 hours that meets the applicable 

requirements of 14 CFR part 33; 

(2) Will have no adverse effect upon the engine. 

(b) Control system malfunctions, vibrations, and abnormal speeds and temperatures expected 

in service may not damage the turbocharger compressor or turbine. 

(c) Each turbocharger case must be able to contain fragments of a compressor or turbine that 

fails at the highest speed that is obtainable with normal speed control devices inoperative. 

(d) Each intercooler installation, where provided, must comply with the following. 

(1) The mounting provisions of the intercooler must be designed to withstand the loads 

imposed on the system; 

(2) It must be shown that, under the installed vibration environment, the intercooler will 

not fail in a manner allowing portions of the intercooler to be ingested by the engine; 

(3) Airflow through the intercooler must not discharge directly on any Airship component 

(e.g. windshield) unless such discharge is shown to cause no hazard to the Airship under 

all operating conditions. 

(e) Engine power, cooling characteristics, operating limits, and procedures affected by the 

turbocharger system installations must be evaluated. Turbocharger operating procedures and 

limitations must be published in the Airship Flight Manual in accordance with HCC.1581. 

HCC.J917 APU drive system 

(a) General: the APU drive system includes any part necessary to transmit power from the 

engines to the electrical generator. This includes gearboxes, shafting, universal joints, 

couplings, brake assemblies, clutches, supporting bearings for shafting, any attendant 

accessory pads or drives, and any cooling fans that are a part of, attached to, or mounted on 

the drive system. The HCC.J918 to J924 must apply. 

HCC.J918 Shafting critical speed 

(a) The critical speeds of any shafting must be determined by demonstration except that 

analytical methods may be used if reliable methods of analysis are available for the particular 

design. 

(b) If any critical speed lies within, or close to, the operating ranges for idling or power-on, 

the stresses occurring at that speed must be within safe limits. This must be shown by tests.

(c) If analytical methods are used and show that no critical speed lies within the permissible 

operating ranges, the margins between the calculated critical speeds and the limits of the 

allowable operating ranges must be adequate to allow for possible variations between the 

computed and actual values. 
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HCC.J919 Shafting joints 

Each universal joint, slip joint and other shafting joints, the lubrication of which is necessary for 

operation must have provision for lubrication.

HCC.J923 APU drive system and control mechanism tests 

(a) Endurance tests, general: each APU drive system and APU control mechanism must be 

tested, as prescribed in subparagraphs (b) to (j) and (m) of this paragraph, for at least 50 

hours. These tests must be conducted as follows: 

(1) Five-hour test cycles must be used. 

(2) The tests must be conducted on the Airship or may be conducted on a representative 

bench test facility. The load, the frequency, and the methods of application to the affected 

APU drive system components must be representative of Airship conditions. Test 

components must be those used for showing compliance with the remainder of this 

paragraph. 

(3) The test torque and rotational speed must be: 

(i) determined by the APU limitations; and 

(ii) absorbed by the APU to be approved for the Airship. 

(b) Endurance tests, maximum RPM run: the maximum RPM run must be conducted as 

follows: 

The maximum RPM torque run must consist of 0.5 hour of alternate runs of 5 minutes at 

maximum RPM torque, and 5 minutes at as low an engine idle speed as practicable. The 

engine must be declutched from the generator drive system if furnished and so intended, must 

be applied during the first minute of the idle run. During the remaining 4 minutes of the idle 

run, the clutch must be engaged so that the engine drives the generator at the minimum 

practical RPM. Acceleration of the engine and the generator drive system must be done at the 

maximum rate. When declutching the engine, it must be decelerated rapidly enough to allow 

the operation of the overrunning clutch. 

(c) Reserved

(d) Endurance tests: 90% of maximum continuous run: 1 hour of continuous operation at 90% 

of maximum continuous torque and the maximum speed for use with 90% of maximum 

continuous torque must be conducted. 

(e) Endurance tests: 80% of maximum continuous run: 1 hour of continuous operation at 80% 

of maximum continuous torque and the minimum speed for use with 80% of maximum 

continuous torque must be conducted. 

(f) Endurance tests: 60% of maximum continuous run: 1 hour of continuous operation at 60% 

of maximum continuous torque and the minimum speed for use with 60% of maximum 

continuous torque must be conducted. 
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(g) Endurance tests: engine malfunctioning run: It must be determined whether 

malfunctioning of components, such as the engine fuel or ignition systems, or whether 

unequal engine power can cause dynamic conditions detrimental to the drive system. If so, a 

suitable number of hours of operation must be accomplished under those conditions. 

(h) Endurance tests: overspeed run: One hour of continuous operation must be conducted at 

maximum continuous torque and the maximum power-on overspeed expected in service, 

assuming that speed and torque limiting devices, if any, function properly. 

(i) Endurance tests, clutch engagements:

A total of at least 100 clutch engagements, including the engagements of subparagraph (b) of 

this paragraph, must be made during the take-off torque runs and, if necessary, at each change 

of torque and speed throughout the test. The clutch engagements must be accomplished at the 

speed and by the method prescribed for the product.

(j) Any APU drive system or control mechanism components that are affected by 

maneuvering must be investigated and their service lives must be determined by fatigue tests 

or by other acceptable methods. 

(k) Each part tested as prescribed in this paragraph must be in a serviceable condition at the 

end of the tests. No intervening disassembly which might affect test results may be conducted. 

(l) Endurance tests; operating lubricants: To be approved for use in APU drive and control 

systems, lubricants must meet the specifications of lubricants used during the tests prescribed 

by this paragraph. Additional or alternate lubricants may be qualified by equivalent testing or 

by comparative analysis of lubricant specifications and APU drive and control system 

characteristics. In addition: 

(1) At least one 10-hour cycle required by this paragraph must be conducted with 

transmission and gearbox lubricant temperatures, at the location prescribed for 

measurement, not lower than the maximum operating temperature for which approval is 

requested; 

(2) For pressure lubricated systems, at least one 10-hour cycles required by this paragraph 

must be conducted with the lubricant pressure, at the location prescribed for measurement,

not higher than the minimum operating pressure for which approval is requested. 

(m) The manufacturer may propose an alternate endurance test procedure if the APU system 

differs in character from that in this part. This test plan must be approved by the 

Administrator.

HCC.J939 Powerplant operating characteristics 

(a) Turbine engine powerplant operating characteristics must be investigated in flight to 

determine that no adverse characteristics (such as stall, surge, or flameout) are present, to a 

hazardous degree, during normal and emergency operation within the range of operating 

limitations of the Airship and of the engine.

(b) Turbocharged reciprocating engine operating characteristics must be investigated in flight 

to assure that no adverse characteristics, as a result of an inadvertent overboost, surge, 
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flooding, or vapor lock, are present during normal or emergency operation of the engine(s) 

throughout the range of operating limitations of both Airship and engine.

(c) For turbine engines, the air inlet system must not, as a result of airflow distortion during 

normal operation, cause vibration harmful to the engine.

(d) It must be established over the range of operating conditions for which certification is 

required that the powerplant installation does not induce engine carcass vibration in excess of 

the acceptable levels established during engine type certification under 14 CFR part 33.83 (e) 

or equivalent. 

(e) For governor-controlled engines, it must be shown that there exists no hazardous torsional 

instability of the drive system associated with critical combinations of power, rotational 

speed, and control displacement.

HCC.J943 Negative acceleration 

No hazardous malfunction of an engine or any component or system associated with the APU 

may occur when the Airship is operated at the negative accelerations within the flight envelopes 

prescribed in HCC.333. This must be shown for the greatest duration expected for the 

acceleration. 

FUEL SYSTEM 

HCC.J951 General 

(a) Each fuel system must be constructed and arranged to ensure a flow of fuel at a rate and 

pressure established for proper engine functioning under each likely operating condition, 

including any maneuver for which certification is requested. 

(b) Each fuel system must be arranged so that 

(1) No fuel pump can draw fuel from more than one tank at a time; or 

(2) There are means to prevent introducing air into the system. 

(c) Each fuel system for a turbine engine must be capable of sustained operation throughout 

its flow and pressure range with fuel initially saturated with water at 80°F (27°C) and having 

0.2 cm3of free water per liter added and cooled to the most critical condition for icing likely 

to be encountered in operation.

(d) Each fuel system for a turbine engine powered Airship must meet the applicable fuel 

venting requirements of 14 CFR part 34.

HCC.J952 Fuel system analysis and test 

(a) Proper fuel system functioning under all probable operating conditions must be shown by 

analysis and those tests found necessary by the Administrator. Tests, if required, must be 

made using the Airship fuel system or a test article that reproduces the operating 

characteristics of the portion of the fuel system to be tested. 

(b) The likely failure of any heat exchanger using fuel as one of its fluids may not result in a 

hazardous condition. 
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(c) Each fuel heat exchanger must be able to withstand without failure any vibration, inertia 

and fuel pressure load to which it may be subjected in operation. 

HCC.J953 Fuel system independence 

Each fuel system must meet the requirements of HCC.J903 (b) by:

(a) Allowing the supply of fuel to each engine through a system independent of each part of 

the system supplying fuel to any other engine; or 

(b) Any other acceptable method. 

HCC.J954 Fuel System lightning protection 

The fuel system must be designed and arranged to prevent the ignition of fuel vapor within the 

system by:

(a) direct lightning strikes to areas having a high probability of stroke attachment; 

(b) swept lightning strokes on areas where swept strokes are highly probable; 

(c) corona or streamering at fuel vent outlets. 

HCC.J955 Fuel Flow 

(a) Each fuel system must provide at least 100% of the fuel flow required under each intended 

operating condition and maneuver. Compliance must be shown as follows: 

(1) Fuel must be delivered to each engine at a pressure, corrected for accelerations (load 

factors), within the limits specified in the engine type certificate. 

(2) The quantity of fuel in the tank may not exceed the amount established as the unusable 

fuel quantity for that tank under the requirements of HCC.959 plus that necessary to show 

compliance with this paragraph. 

(3) Each main pump must be used that is necessary for each operating condition and 

attitude for which compliance with this paragraph is shown, and the appropriate emergency 

pump must be substituted for each main pump so used. 

(4) If there is a fuel flowmeter, it must be blocked and the fuel must flow through the meter 

or its bypass. 

(5) The fuel head between the tank and the engine must be critical with respect to Airship 

flight attitudes. 

(b) If an engine can be supplied with fuel from more than one tank, the fuel system must for 

each engine, in addition to having appropriate manual switching capability, be designed to 

prevent interruption of fuel flow to that engine, without attention by the flight crew, when any 

tank supplying fuel to that engine is depleted of usable fuel during normal operation, and any 

other tank, that normally supplies fuel to that engine alone, contains usable fuel. 

HCC.J961 Fuel system hot weather operation 

(a) The fuel system must perform satisfactorily in hot weather operation. This must be shown 

by demonstrating that the fuel system from the tank outlets to each engine is pressurized, 

under all intended operations, so as to prevent vapor formation, or must be shown by climbing 

from the altitude of the airport elected for the product to the maximum altitude established as 
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an operating limitation under HCC.1527. If a climb test is elected, there must be no evidence 

of vapor lock or other malfunctioning during the climb test conducted under the following 

conditions:

(1) For piston engine APUs, the power settings should be maintained at the maximum 

approved levels during takeoff and climb to provide for the maximum fuel flow. The climb 

should be continued to the maximum operating altitude approved for the Airship. If a

lower altitude is substantiated, appropriate limitations should be published in the Airship 

Flight Manual. 

(2) For turbine engine APUs, the engines must operate at maximum RPM for the time 

interval selected for showing the takeoff flight path, and at maximum continuous power for 

the rest of the climb.

(3) The mass of the Airship must be with full fuel tanks, minimum crew, and the ballast 

necessary to maintain the center of gravity within allowable limits or other combinations 

approved by the Administrator. 

(4) The climb airspeed may not exceed the maximum airspeed established for climbing 

from takeoff to the maximum operating altitude. 

(5) The fuel temperature must be at least 110oF (43°C). 

(b) The test prescribed in subparagraph (a) of this paragraph may be performed in flight or on 

the ground under closely simulated flight conditions. If a flight test is performed in weather 

cold enough to interfere with the proper conduct of the test, the fuel tank surfaces, fuel lines, 

and other fuel system parts subject to cold air must be insulated to simulate, insofar as 

practicable, flight in hot weather. 

HCC.J975 Carburetor vapor vents

(a) Reserved

(b) Each carburetor with vapor elimination connections and each fuel injection engine 

employing vapor return provisions must have a separate vent line to lead vapors back to the 

top of a fuel tank. If there is more than one fuel tank, and it is necessary to use these tanks in a 

definite sequence for any reason, the vapor vent return line must lead back to the fuel tank to 

be used first, unless the relative capacities of the tanks are such that return to another tank is 

preferable.

HCC.J977 Fuel tank outlet 

(a) There must be a fuel strainer for the fuel tank outlet or for the booster pump. This strainer 

must 

(1) For reciprocating engine-powered APUs, have 8 to 16 meshes per inch (3 to 6 meshes 

per cm); 

(2) For turbine engine-powered Airships, prevent the passage of any object that could 

restrict fuel flow or damage any fuel-system component.

(b) The clear area of each fuel tank outlet strainer must be at least five times the area of the 

outlet line. 
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(c) The diameter of each strainer must be at least that of the fuel tank outlet. 

(d) Each finger strainer must be accessible for inspection and cleaning. 

FUEL SYSTEM COMPONENTS 

HCC.J991 Fuel pumps 

(a) Main pumps: each fuel pump required for proper engine operation, or required to meet the 

fuel system requirements of this Subpart (other than those in subparagraph (b) of this 

paragraph), is a main pump. For each main pump, provision must be made to allow the bypass 

of each positive displacement fuel pump approved as part of the engine. 

(b) Emergency pumps: there must be emergency pumps or another main pump to feed each 

engine immediately after failure of any main pump. 

(c) Warning means: If both the normal pump and emergency pump operate continuously, 

there must be a means to indicate to the appropriate flight crewmember a malfunction of 

either pump. 

(d) Operation of any fuel pump may not affect engine operation so as to create a hazard, 

regardless of the engine power or RPM setting or functional status of any other fuel pump. 

HCC.J993 Fuel system lines and fittings 

(a) Each fuel line must be installed and supported to prevent excessive vibration and to 

withstand loads due to fuel pressure and accelerated flight conditions. 

(b) Each fuel line connected to components of the Airship between which relative motion 

could exist must have provisions for flexibility. 

(c) Each flexible connection in fuel lines that may be under pressure and subjected to axial 

loading must use flexible hose assemblies. 

(d) Each flexible hose must be approved or must be shown to be suitable for the particular 

application. 

(e) No flexible hose that might be adversely affected by exposure to high temperatures may be 

used where excessive temperatures will exist during operation or after engine shutdown. 

(f) Each fuel line must be designed and installed to allow a reasonable degree of deformation 

and stretching without leakage. 

HCC.J994 Fuel system components 

Fuel system components must be protected from damage which could result in spillage of 

enough fuel to constitute a fire hazard as a result of an ACLS retracted landing.

HCC.J995 Fuel valves 

There must be a means to allow appropriate flight crew members rapidly to shut off the fuel to 

each engine individually in flight. In addition to the requirements of HCC.J1189 for shut-off 

means, each fuel valve must: 

(a) Reserved
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(b) be supported so that no loads resulting from their operation or from accelerated flight 

conditions are transmitted to the lines attached to the valve. 

HCC.J997 Fuel strainer or filter 

(This paragraph does not apply to fuel strainers or filters already approved as part of an engine 

type certificated under 14 CFR part 33 or equivalent.) 

There must be a fuel strainer or filter between the fuel tank outlet and the inlet of either the fuel 

metering device or an engine-driven positive displacement pump, whichever is nearer the fuel 

tank outlet. This fuel strainer or filter must 

(a) Be accessible for draining and cleaning and must incorporate a screen or element which is 

easily removable; 

(b) Have a sediment trap and drain except that it need not have a drain if the strainer or filter 

is easily removable for drain purposes; 

(c) Be mounted so that its weight is not supported by the connecting lines or by the inlet or 

outlet connections of the strainer or filter itself; 

(d) Have the capacity (with respect to operating limitations established for the engine) and the 

mesh to ensure that engine fuel system functioning is not impaired, with the fuel contaminated 

to a degree (with respect to particle size and density) that is greater than the established for the 

engine in 14 CFR part 33, or equivalent regulations. 

(e) In addition, unless means are provided in the fuel system to prevent the accumulation of 

ice on the filter, a means must be provided to automatically maintain the fuel flow if ice 

clogging of the filter occurs. 

HCC.J999 Fuel system drains 

(a) Drainage of the fuel system must be accomplished by the use of fuel strainer and fuel tank 

sump drains 

(b) Each drain required by subparagraph (a) of this paragraph and HCC.971 must 

(1) discharge clear of all parts of the Airship; 

(2) Have manual or automatic means for positive locking in the closed position; 

(3) Have a drain valve that is readily accessible and which can be easily opened and 

closed; and that is either located or protected to prevent fuel spillage in dangerous 

quantities in the event of an unintended contact with the ground.

OIL SYSTEM 

HCC.J1011 General 

(a) Each engine must have an independent oil system that can supply it with an appropriate 

quantity of oil at a temperature not above that safe for continuous operation. 

(b) The usable oil tank capacity may not be less than the product of the endurance of the 

Airship under critical operating conditions and the maximum oil consumption of the engine 

under the same conditions, plus a suitable margin to ensure adequate circulation and cooling. 
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(c) For an oil system without an oil transfer system, only the usable oil tank capacity may be 

considered. The amount of oil in the engine oil lines, the oil radiator, and the feathering 

reserve, may not be considered. 

(d) If an oil transfer system is used, the amount of oil in the transfer lines that can be pumped 

by the transfer pump must be included in the oil capacity. 

HCC.J1013 Oil tanks 

(This paragraph does not apply to oil tanks already approved as part of an engine type 

certificated under 14 CFR part 33.) 

(a) Installation: each oil tank must be installed to: 

(1) meet the requirements of HCC.J967; 

(2) withstand any vibration, inertia, and fluid loads expected in operation. 

(b) Expansion space: oil tank expansion space must be provided so that 

(1) Each oil tank used with a reciprocating engine has an expansion space of not less than 

the greater of 10% of the tank capacity or 0.5 US-gallons (1.9 liter), and each oil tank used 

with a turbine engine has an expansion space of not less than 10% of the tank capacity;

(2) It is impossible to fill the expansion space inadvertently with the Airship in the normal 

ground attitude. 

(3) Each reserve oil tank not directly connected to any engine may have an expansion 

space of not less than 2% of the tank capacity. 

(c) Filler connection: each recessed oil tank filler connection that can retain any appreciable 

quantity of oil must have a drain that discharges clear of each part of the Airship. In addition: 

(1) Each oil tank filler cap must provide an oil tight seal; 

(2) Each oil tank filler must be marked as prescribed in HCC.1557(c). 

(d) Vent: oil tanks must be vented as follows: 

(1) Each oil tank must be vented from the top part of the expansion space so that the vent 

connection is not covered by oil under any normal flight condition; 

(2) Oil tank vents must be arranged so that condensed water vapor that might freeze and 

obstruct the line cannot accumulate at any point.

(e) Outlet: no oil tank outlet may be enclosed by any screen or guard that would reduce the 

flow of oil below a safe value at any operating temperature. No oil tank outlet diameter may 

be less than the diameter of the engine oil pump inlet. Each oil tank used with a turbine engine 

must have means to prevent entrance into the tank itself, or into the tank outlet, of any object 

that might obstruct the flow of oil through the system. There must be a shutoff valve at the 

outlet of each oil tank used with a turbine engine, unless the external portion of the oil system 

(including of tank supports) is fireproof. 

(f) Flexible liners: each flexible oil tank liner must be approved or must be shown to be 

suitable for the particular application. 
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(g) Each filler cap of an oil tank that is used with a turbine engine must provide an oil tight 

seal. 

HCC.J1015 Oil tank tests 

(This paragraph does not apply to oil tanks already approved as part of an engine type 

certificated under 14 CFR part 33.) 

Each oil tank must be designed and installed so that: 

(a) It can withstand, without failure, each vibration, inertia, and fluid load that it may be 

subjected to in operation; and

(b) It meets the provisions of HCC.965, except: 

(1) The test pressure: 

(i) For pressurized tanks used with a turbine engine, may not be less than 5 psi (34.45 

kPa) plus the maximum operating pressure of the tank instead of the pressure specified 

in HCC.965(a); and

(ii) For all other tanks, may not be less than 5 psi (34.45 kPa) instead of the pressure 

specified in HCC.965(a); and 

(2) The test fluid must be oil at 250oF (120°C) instead of the fluid specified in HCC.965(c). 

HCC.J1017 Oil lines and fittings 

(a) Oil lines: oil lines must meet HCC.J993, and each oil line and fitting in any designated fire 

zone must meet the requirements of HCC.J1183. Oil lines must accommodate a flow of oil at 

a rate and pressure adequate for proper engine functioning under any normal operating 

condition. 

(b) Breather lines: breather lines must be arranged so that 

(1) condensed water vapor or oil that might freeze and obstruct the line cannot accumulate 

at any point;

(2) the breather discharge will not constitute a fire hazard if foaming occurs, or cause 

emitted oil to strike the pilot's windshield; 

(3) the breather does not discharge into the engine air-induction system; 

(4) the breather outlet its protected against blockage by ice or foreign matter. 

HCC.J1019 Oil strainer or filter 

(This paragraph does not apply to oil strainers or filters already approved as part of an engine 

type certificated under 14 CFR part 33 or equivalent.) 

(a) Each turbine engine installation must incorporate an oil strainer or filter through which all 

of the engine oil flows and which meets the following requirements. 

(1) Each oil strainer or filter that has a bypass must be constructed and installed so that oil 

will flow at the normal rate through the rest of the system with the strainer or filter 

completely blocked. 
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(2) The oil strainer or filter must have the capacity (with respect to operating limitations 

established for the engine) and the mesh to ensure that engine oil system functioning is not 

impaired when the oil is contaminated to a degree (with respect to particle size and 

density) that is greater than that established for the engine in 14 CFR part 33 or equivalent 

regulations.

(3) The oil strainer or filter, unless it is installed at an oil tank outlet, must incorporate an 

indicator that will indicate contamination of the screen before it reaches the capacity 

established in accordance with subparagraph (2) of this paragraph. 

(4) The bypass of a strainer or filter must be constructed and installed so that the release of 

collected contaminants is minimized by appropriate location of the bypass to ensure that 

collected contaminants are not in the bypass flow path.

(5) An oil strainer or filter that has no bypass, except on that is installed at an oil tank 

outlet, must have a means to connect it to the warning system required in subparagraph 

1305(c)(7). 

(b) Each oil strainer or filter in a powerplant installation using reciprocating engines must be 

constructed and installed so that oil will flow at the normal rate through the rest of the system 

with the strainer or filter element completely blocked. 

HCC.J1021 Oil system drains 

A drain (or drains) must be provided to allow safe drainage of the oil system. Each drain must: 

(a) Be accessible; and 

(b) Have manual or automatic means for positive locking in the closed position. 

HCC.J1023 Oil radiators 

If installed: 

(a) each oil radiator and its supporting structures must be able to withstand the vibration, 

inertia, and oil pressure loads to which it would be subjected in operation. 

(b) each oil radiator air duct must be located so that, in case of fire, flames coming from 

normal openings of the engine nacelle cannot impinge directly upon the radiator.

HCC.J1025 Oil valves 

(a) Each oil shut-off must meet the requirements of HCC.J1189. 

(b) Reserved

(c) Each oil valve must have positive stops or suitable index provisions in the 'on' and 'off ' 

positions and must be supported so that no loads resulting from its operation or from 

accelerated flight conditions are transmitted to the lines attached to the valve. 

COOLING 

HCC.J1041 General 

The APU cooling provisions must be able to maintain the temperatures of the APU components 

and engine fluids, within the temperature limits established during ground and flight operations 

to the maximum altitude for which approval is requested and after normal engine shutdown. 
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HCC.J1043 Cooling tests 

(a) General: compliance with HCC.J1041 must be shown under critical ground and flight 

operating conditions (including loiter, hover, climb, and descent) to the maximum altitude for 

which approval is requested. For turbocharged engines, each turbocharger must be operated 

through that part of the climb profile for which operation with the turbocharger is requested 

and in a manner consistent with its intended operation. For these tests, the following apply. 

(1) If the tests are conducted under conditions deviating from the maximum ambient 

atmospheric temperature specified in subparagraph (b), of this paragraph, the recorded 

APU temperature must be corrected under paragraphs (c) and (d) of this paragraph, unless 

a more rational correction method is applicable. 

(2) No corrected temperature determined under subparagraph (1) of this paragraph may 

exceed established limits. 

(3) The fuel used during the cooling tests must be of the minimum grade approved for the 

engines, and for reciprocating engines the mixture settings must be the leanest 

recommended for flight. 

(b) Maximum ambient atmospheric temperature: a maximum ambient atmospheric 

temperature corresponding to sea level conditions of at least 100°F (38°C) must be 

established. The assumed temperature lapse rate is 3.6°F (2°C) per thousand feet of altitude 

above sea level. However, for winterization installations, a maximum ambient atmospheric 

temperature corresponding to sea level conditions of less than 100°F (38°C) may be selected 

for the product. 

(c) Correction factor (except cylinder barrels): Unless a more rational correction applies, 

temperatures of engine fluids and APU components (except cylinder barrels) for which 

temperature limits are established, must be corrected by adding to them the difference 

between the maximum ambient atmospheric temperature and the temperature of the ambient 

air at the time of the first occurrence of the maximum component or fluid temperature 

recorded during the cooling test. 

(d) Correction factor for cylinder barrel temperatures: Cylinder barrel temperatures must be 

corrected by adding to them 0.7 times the difference between the maximum ambient 

atmospheric temperature and the temperature of the ambient air at the time of the first 

occurrence of the maximum cylinder barrel temperature recorded during the cooling test. 

HCC.J1045 Cooling test procedures 

(a) General: Compliance with HCC.J1041 must be shown for the takeoff, climb, en-route, and 

landing stages of flight that correspond to the applicable performance requirements. For each 

stage of flight, the cooling test must be conducted with the Airship 

(1) In the configuration most critical for cooling (including cowl flap settings selected for 

the product for reciprocating engine powered APUs, if applicable).

(2) Under the operational conditions most critical for cooling. 
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(b) Temperature stabilization: For the purpose of the cooling tests, a temperature is 'stabilized' 

when its rate of change is less than 2°F (1.1°C) per minute. The following stabilization rules 

apply for each stage of flight:

(1) The temperatures must be stabilized under the conditions from which entry is made 

into the stage of flight being investigated; or

(2) If the entry condition normally does not allow temperatures to stabilize, operation 

through the full entry condition must be conducted before entry into the stage of flight 

being investigated in order to allow the temperatures to have attained their natural levels at 

the time of entry.

(c) Duration of test: For each stage of flight the test must be continued until 

(1) The component and engine-fluid temperatures stabilize; or

(2) The stage of flight is completed; or 

(3) An operating limitation is reached. 

(d) Turbine engine powered APUs: The following additional requirement applies: The takeoff cooling test must be preceded by a period during which the APU component and enginefluid temperatures are stabilized with the engines at ground idle.

(e) For reciprocating engine-powered APUs, engine-cooling tests during climb must be 

conducted as follows: 

(1) Reserved 

(2) Engine temperature must be stabilized in level flight with the engine at not less than 

75% of maximum continuous power.

(3) The climb must begin at the lowest practicable altitude with the engine at full power for 

the specified duration of takeoff and then remain at full power. 

(4) The climb must be conducted at a speed not more than the best rate of climb speed with 

maximum continuous power unless the slope of the flight path at the speed chosen for the 

cooling test is equal to or greater than the minimum required angle of climb determined 

under HCC.65 and the Airship has a cylinder head temperature indicator. 

(5) The APU must continue at full power for at least 5 minutes after the occurrence of the 

highest temperature recorded (or pressure height). 

(f) The hovering cooling provisions must be shown: 

(1) Reserved

(2) Reserved

(3) With the APU at full power, until at least 5 minutes after the occurrence of the highest 

temperature recorded. 
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LIQUID COOLING 

HCC.J1061 Installation 

(a) General: Each liquid-cooled engine must have an independent cooling system (including 

coolant tank) installed so that: 

(1) Each coolant tank is supported so that tank loads are distributed over a large part of the 

tank surface; 

(2) There are pads or other isolation means between the tank and its supports to prevent 

chafing; and 

(3) Pads or any other isolation means that is used must be non-absorbent or must be treated 

to prevent absorption of flammable fluids; and 

(4) No air or vapor can be trapped in any part of the system, except the coolant tank 

expansion space, during filling or during operation.

(b) Coolant tank: The tank capacity must be at least 1 US-gallon (3.8 liters), plus 10% of the 

cooling system capacity. In addition:

(1) Each coolant tank must be able to withstand the vibration, inertia and fluid loads to 

which it may be subjected in operation; 

(2) Each coolant tank must have an expansion space of at least 10% of the total cooling 

system capacity; and 

(3) It must be impossible to fill the expansion space inadvertently with the Airship in the 

normal ground attitude. 

(c) Filler connection: Each coolant tank filler connection must be marked as specified in 

HCC.1557 In addition: 

(1) Spilled coolant must be prevented from entering the coolant tank compartment or any 

part of the Airship other than the tank itself; and 

(2) Each recessed coolant filler connection must have a drain that discharges clear of the 

entire Airship. 

(d) Lines and fittings: Each coolant system line and fitting must meet the requirements of 

HCC.J993, except that the inside diameter of the engine coolant inlet and outlet lines may not 

be less than the diameter of the corresponding engine inlet and outlet connections. 

(e) Radiators: Each coolant radiator must be able to withstand any vibration, inertia and 

coolant pressure load to which it may normally be subjected. In addition: 

(1) Each radiator must be supported to allow expansion due to operating temperatures and 

prevent the transmittal of harmful vibration to the radiator; and 

(2) If flammable coolant is used, the air intake duct to the coolant radiator must be located 

so that (in case of fire) flames from the nacelle cannot strike the radiator. 

(f) Drains: There must be an accessible drain that: 
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(1) Drains the entire cooling system (including the coolant tank, radiator and the engine) 

when the Airship is in the normal ground attitude; 

(2) Discharges clear of the entire Airship; and 

(3) Has means to lock it closed positively. 

HCC.J1063 Coolant tank tests 

Each coolant tank must be tested under HCC.965, except that: 

(a) The test required by HCC.965 (a) (1) must be replaced with a similar test using the sum of 

the pressure developed during the maximum ultimate acceleration with a full tank or a 

pressure of 3.5 psi (24.12 kPa), whichever is greater, plus the maximum working pressure of 

the system; and: 

(b) For a tank with a non-metallic liner the test fluid must be coolant rather than fuel as 

specified in HCC.965 (c) and the slosh test on a specimen liner must be conducted with the 

coolant at operating temperature. 

INDUCTION SYSTEM 

HCC.J1091 Air intake 

(a) The air intake system for each engine must supply: 

(1) the air required by that engine under the operating conditions for which certification is 

requested, and: 

(2) The air for proper fuel metering and mixture distribution with the air intake system 

valves in any position. 

(b) Each reciprocating engine installation must have at least two separate air intake sources 

and must meet the following. 

(1) Primary air intakes may open within the cowling if that part of the cowling is isolated 

from the engine accessory section by a fire-resistant diaphragm or if there are means to 

prevent the emergence of backfire flames. 

(2) Each alternate air intake must be located in a sheltered position and may not open 

within the cowling if the emergence of backfire flames will result in a hazard. 

(3) The supplying of air to the engine through the alternate air intake system may not result 

in a loss of excessive power in addition to the power loss due to the rise in air temperature. 

(4) Each automatic alternate air door must have an override means accessible to the flight 

crew. 

(5) Each automatic alternate air door must have a means to indicate to the flight crew when 

it is not closed 

(c) For air intakes for turbine engine-powered installations the following apply: 

(1) Air intakes may not open within the cowling, unless that part of the cowling is isolated 

from the engine accessory section by means of a fireproof diaphragm; 
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(2) There must be means to prevent hazardous quantities of fuel leakage or overflow from 

drains, vents, or other components of flammable fluid systems from entering the engine 

intake system; 

(3) The air inlet ducts must be located or protected so as to minimize the ingestion of 

foreign matter during take-off, landing, parking and taxiing;

(4) If the engine air intake system contains parts or components that could be damaged by 

foreign objects entering the air intake, it must be shown by tests or, if appropriate, by 

analysis that the air intake system design can withstand the foreign object ingestion test 

conditions of 14 CFR part 33 without failure of parts or components that could create a 

hazard. 

HCC.J1093 Air intake system de-icing and anti-icing provisions 

(a) Reciprocating gasoline engines: Each reciprocating gasoline engine air-induction system 

must have means to prevent and eliminate icing. Unless this is done by other means, it must 

be shown that, in air free of visible moisture at a temperature of 30°F (-1.1°C): 

(1) Each Airship with altitude engines using fuel metering devices tending to prevent icing 

has a preheater that, with the engines at 60% of maximum continuous power, can provide a 

temperature rise of: 

(i) 100°F (56°C); or 

(ii) 40°F (22°C), if a fluid de-icing system meeting the requirements of 14 CFR part

23.1095 through 23.1099 is installed; 

(2) Each Airship with sea level engine(s) using a fuel metering device tending to prevent 

icing has a sheltered alternate source of air with a preheat temperature rise of not less than 

60°F (33°C) with the engines at 75% of maximum continuous power; 

(3) Each Airship with sea level or altitude engine(s) using fuel injection systems having 

metering components on which impact ice may accumulate has a preheater capable of 

providing a temperature rise of 75°F (42°C) when the engine is operating at 75% of its 

maximum continuous power; and:

(4) Each Airship with sea level or altitude engine(s) using fuel injection systems not 

having fuel metering components projecting into the airstream on which ice may form, and 

introducing fuel into the air induction system downstream of any components or other 

obstruction on which ice produced by fuel evaporation may form, has a sheltered alternate 

source of air with a preheat temperature rise of not less than 60°F (33°C) with the engines 

at 75% of its maximum continuous power.

(b) Turbine engines

(1) Each turbine engine and its air-inlet system must operate throughout the flight-power 

range of the engine (including idling), within the limitations established for the Airship, 

without the accumulation of ice on engine or inlet system components that would 

adversely affect engine operation or cause a serious loss of power or. 

(i) Under the icing conditions specified in 14 CFR part 25 Appendix C; 
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(ii) In snow, both falling and blowing. 

(2) Each turbine engine must idle for 30 minutes on the ground, with the air bleed available 

for engine icing protection at its critical condition, without adverse effect, in an atmosphere 

that is at a temperature between 15°F (-9°C) and 30°F (-1°C) and has a liquid water 

content not less than 0.3 grams per cubic meter in the form of drops having a mean 

effective diameter not less than 20 micrometers, followed by momentary operation at takeoff power or thrust. During the 30 minutes of idle operation, the engine may be run up 

periodically to a moderate power or thrust setting in a manner acceptable to the 

Administrator.

(c) For Airships with reciprocating engines having superchargers or turbocharges to 

pressurize the air before it enters the carburetor, the temperature rise in the air caused by that 

pressurizing at any altitude may be utilized in determining compliance with subparagraph (a) 

of this paragraph if the heat rise utilized is that which will be available, automatically, for the 

applicable altitudes and operating condition because of supercharging or turbochanging.

HCC.J1101 Carburetor air preheater design

Each exhaust-heated, induction air preheater must be designed and constructed to:

(a) Ensure ventilation of the preheater when the induction air preheater is not being used 

during engine operation.

(b) Allow inspection of the exhaust manifold parts that it surrounds; and

(c) Allow inspection of critical parts of the preheater itself.

HCC.J1103 Induction system ducts 

(a) Each induction system duct must have a drain to prevent the accumulation of fuel or 

moisture in the normal ground and flight attitudes. No drain may discharge where it will cause 

a fire hazard. 

(b) Each turbine air intake system must be: 

(1) Strong enough to prevent structural failure resulting from engine surging; and 

(2) Fire-resistant if it is in any fire zone for which a fire extinguishing system is required. 

(c) Each duct connected to components between which relative motion could exist must have 

means for flexibility. 

(d) For bleed air systems no hazard may result if a duct rupture or failure occurs at any point 

between the engine port and the Airship unit served by the bleed air.

(e) For reciprocating engine installations, each induction system duct must be: 

(1) Strong enough to prevent induction system failures resulting from normal backfire 

conditions; and 

(2) Fire resistant in any compartment for which a fire extinguishing system is required. 

HCC.J1105 Air intake system screens 

If induction system screens are used: 
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(a) Each screen must be upstream of the fuel metering device; 

(b) No screen may be in any part of the induction system that is the only passage through 

which air can reach the engine, unless 

(1) The available preheat temperature rise is at least 100°F (55.6°C), and

(2) The screen can be de-iced by heated air;

(c) No screen may be de-iced by alcohol alone; and

(d) It must be impossible for fuel to strike any screen 

HCC.J1107 Inter-coolers and after-coolers 

Each inter-cooler and after-cooler must be able to withstand any vibration, inertia, and air 

pressure load to which it would be subjected in operation. 

HCC.J1108 Induction system filters 

If an air filter, is used to protect the engine against foreign material particles in the induction air 

supply, it must be capable of withstanding the effects of temperature extremes, rain, fuel, oil, and 

solvents to which it is expected to be exposed in service and maintenance. 

HCC.J1111 Turbine engine bleed-air system 

For turbine engine bleed-air systems, the following apply.

(a) No hazard may result if duct rupture or failure occurs anywhere between the engine port 

and the Airship unit served by the bleed air.

(b) The effect on Airship and engine performance of using maximum bleed air must be 

established. 

(c) Hazardous contamination of cabin air systems may not result from failures of the engine 

lubricating system. 

(d) Bleed air must not discharge directly on any Airship component (e.g. windshield) unless 

such discharge is shown to cause no hazard to the Airship under all operating conditions. 

EXHAUST SYSTEM 

HCC.J1121 General 

(a) Each exhaust system must ensure safe disposal of exhaust gases without fire hazard or 

carbon monoxide contamination in any crew or passenger compartment. For test purposes, 

any acceptable carbon monoxide detection method may be used to show the absence of 

carbon monoxide. 

(b) Each exhaust system part with a surface hot enough to ignite flammable fluids or vapors 

must be located or shielded so that leakage from any system carrying flammable fluids or 

vapors will not result in a fire caused by impingement of the fluids or vapors on any part of 

the exhaust system including shields for the exhaust system.

(c) Each component that hot exhaust gases could strike, or that could be subjected to high 

temperatures from exhaust system parts, must be fireproof. All exhaust system components 

must be separated by fireproof shields from adjacent parts of the Airship that are outside the 

engine compartment. 
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(d) No exhaust gases may discharge near any flammable fluid, vent, or drain that may cause a 

fire hazard. 

(e) Each exhaust shroud must be ventilated or insulated to avoid, during normal operation, a 

temperature high enough to ignite any flammable fluids or vapors external to the shroud. 

(f) No exhaust gases may be discharged where they will cause a glare seriously affecting pilot 

vision at night. 

(g) If significant traps exist, each turbine engine exhaust system must have drains discharging 

clear of the Airship, in any normal ground and flight attitude, to prevent fuel accumulation 

after the failure of an attempted engine start. 

(h) Each exhaust heat exchanger must incorporate means to prevent blockage of the exhaust 

port after any internal heat exchanger failure. 

HCC.J1123 Exhaust piping 

(a) Each exhaust piping must be fireproof and corrosion-resistant, and must have means to 

prevent failure due to expansion caused by operating temperatures. 

(b) Each exhaust piping must be supported to withstand the vibration and inertia loads to 

which it may be subjected in operation. 

(c) Parts of the exhaust system connected to components between which relative motion could 

exist must have means for flexibility. 

HCC.J1125 Exhaust heat exchangers 

For reciprocating engine-powered Airships, the following apply: 

(a) Each exhaust heat exchanger must be constructed and installed to withstand the vibration, 

inertia, and other loads to which it will be subject in normal operation. In addition: 

(1) Each exchanger must be suitable for continued operation at high temperatures and 

resistant to corrosion from exhaust gases;

(2) There must be means for inspection of the critical parts of each exchanger;

(3) Each exchanger must be ventilated wherever it is subject to contact with exhaust gases.

(4) No exhaust heat exchanger or muffler may have any stagnant areas or liquid traps that 

would increase the probability of ignition of flammable fluids or vapors that might be 

present in case of the failure or malfunction of components carrying flammable fluids.

(b) If an exhaust heat exchanger is used for heating ventilating air: 

(1) There must be a secondary heat exchanger between the primary exhaust gas heat 

exchanger and the ventilating air system; or

(2) Other means must be used to preclude the harmful contamination of the ventilating air. 

APU CONTROLS AND ACCESSORIES 

HCC.J1141 APU controls: general 

Each APU control shall be located, arranged, and designed under HCC.777 and 779 and marked 

under HCC.1555. In addition, it must meet the following requirements: 
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(a) Each control shall be located so that it cannot be operated inadvertently by persons 

entering, leaving, or moving normally in the cockpit. 

(b) Each flexible control shall be approved or must be shown to be suitable for the particular 

application. 

(c) Each control shall have sufficient strength and rigidity to withstand operating loads 

without failure and without excessive deflection. 

(d) Each control shall be able to maintain any set position without constant attention by flightcrew members and without creep due to control loads or vibration. 

(e) The portion of each powerplant control located in a designated fire zone that is required to 

be operated in the event of fire shall be at least fire resistant. (See HCC.903(c)(2).)

(f) APU valve controls located in the cockpit must have 

(1) For manual valves, positive stops or in the case of fuel valves suitable index provisions, 

in the open and closed positions; and 

(2) In the case of valves controlled from the cockpit other than by mechanical means, 

where the correct functioning of such a valve is essential for the safe operation of the 

Airship, a valve position indicator operated by a system which senses directly that the 

valve has attained the position selected, unless other indications in the cockpit give the 

flight crew a clear indication that the valve has moved to the selected position.

HCC.J1143 APU Engine controls 

(a) There shall be a separate and independent power control for each engine, and a separate 

control for each supercharger that requires a control. 

(b) The controls shall be grouped and arranged to allow separate control of each APU engine. 

(c) Each power and supercharger control must give a positive and immediately response in 

controlling its engine or supercharger.

(d) Reserved

(e) If a power control incorporates a fuel-shut-off feature, the control must have a means to 

prevent the inadvertent movement of the control into the shut-off position. The control must

(1) Have a positive lock or stop at the idle position; 

(2) Require a separate and distinct operation to place the control in the shut-off position. 

HCC.J1145 Ignition switches 

(a) Ignition switches must control each ignition circuit on each engine.

(b) There must be means to shut off quickly all ignition either by a group of switches or by a 

master ignition control. 

(c) Each group of ignition switches, except ignition switches for turbine engines for which 

continuous ignition is not required, and each master ignition control must have a means to 

prevent its inadvertent operation. 

(d) Pre-glow switches for Diesel engines are to be treated the same as ignition switches. 
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HCC.J1147 Mixture controls 

(a) If there are mixture controls, each engine must have a separate control and each mixture 

control must have guards or must be shaped or arranged to prevent confusion by feel with 

other controls. 

(1) The controls must be grouped and arranged to allow:

(i) Separate control of each engine; and: 

(ii) Simultaneous control of all functionally related engines. 

(2) The control must require a separate and distinct operation to move the control towards 

lean or shut-off position. 

(b) Each manual engine mixture control must be designed so that, if the control separates at 

the engine fuel metering device, the Airship is capable of continuing safe flight. 

HCC.J1157 Carburetor air temperature controls

If there is a carburetor air temperature control, it must be separate for each engine.

HCC.J1163 APU Powerplant accessories 

(a) Each engine-driven accessory must: 

(1) Be approved for mounting on the engine involved; 

(2) Use the provisions on the engine for mounting; 

(3) Be sealed to prevent contamination of the engine oil system and the accessory system. 

(b) Electrical equipment subject to arcing or sparking must be installed to minimize the 

probability of contact with any flammable fluids or vapors that might be present in a free 

state.

(c) Each generator rated at or more than 6 kW must be designed and installed to minimize the 

probability of a fire hazard in the event it malfunctions.

(d) If the continued rotation of any accessory remotely driven by the engine is hazardous 

when malfunctioning occurs, a means to prevent rotation without interfering with the 

continued operation of the engine must be provided. 

(e) The generator cooling provisions must be able to maintain the temperatures of generator 

components within the established temperature limits during ground and flight operations. 

(f) Each accessory driven by a gearbox that is not approved as part of the powerplant driving 

the gearbox must: 

(1) Have torque limiting means to prevent the torque limits established for the affected 

drive from being exceeded; 

(2) Use the provisions on the gearbox for mounting; and 

(3) Be sealed to prevent contamination of the gearbox oil system and the accessory system.
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HCC.J1165 Engine ignition systems 

(a) Each battery ignition system must be supplemented by a generator that is automatically 

available as an alternate source of electrical energy to allow continued engine operation if any 

battery becomes depleted. 

(b) The capacity of batteries and generators must be large enough to meet the simultaneous 

demands of the engine ignition system and the greatest demands of any electrical system 

components that draw electrical energy from the same source.

(c) The design of the engine ignition system must account for: 

(1) the condition of an inoperative generator; 

(2) the condition of a completely depleted battery with the generator running at its normal 

operating speed; and 

(3) the condition of a completely depleted battery with the generator operating at idling 

speed, if there is only one battery. 

(d) There must be means to warn appropriate crew members if malfunctioning of any part of 

the electrical system is causing the continuous discharge of any battery used for engine 

ignition. 

(e) No ground wire for any engine may be routed through a fire zone of another engine unless 

each part of that wire within that zone is fireproof. 

(f) Each ignition system must be independent of any electrical circuit not used for assisting, 

controlling, or analyzing the operation of that system.

(g) There must be means to warn appropriate flight-crew members if the malfunctioning of 

any part of the electrical system is causing the continuous discharge of any battery necessary 

for engine ignition.

(h) Each engine ignition system must be considered an essential electrical load. 

APU POWERPLANT FIRE PROTECTION 

HCC.J1181 Designated fire zones: regions included 

(a) Designated fire zones are -

(1) The engine power section; 

(2) The engine accessory section; 

(3) Any complete APU compartment in which no isolation is provided between the engine 

section and the engine accessory section; 

(4) Reserved

(5) The compressor and accessory sections of turbine engines; and 

(6) Combustor, turbine, and tailpipe sections of turbine engine installations that contain 

lines or components carrying flammable fluids or gases. 

(b) Each designated fire zone must meet the requirements of HCC.869, J1185 to J1203. 
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(c) Each Airship must: 

(1) Be designed and constructed so that no fire originating in any fire zone can enter, either 

through openings or by burning through external skin, any other zone or region where it 

would create additional hazards; 

(2) Meet subparagraph (c) (1) of this paragraph with the ACLS retracted (if applicable); 

and 

(3) Have fireproof skin in areas subject to flame if a fire starts in the engine power or 

accessory section. 

HCC.J1182 Areas behind firewalls, and engine pod attaching structures containing 

flammable fluid lines 

(a) Each area immediately behind the firewall, and each portion of any engine pod attaching 

structure containing flammable fluid lines, must meet each requirement of HCC.J1103, J1165 

(e), J1183, J1185 (c), J1187, J1189 and HCC.J1195 to J1203, including those concerning 

designated fire zones. However, engine pod attaching structures need not contain fire 

detection or extinguishing means. 

HCC.J1183 Flammable fluid-carrying components 

(a) Except as provided in subparagraph (b) of this paragraph, each line, fitting, and other 

component carrying flammable fluid in any area subject to engine fire conditions, and each 

component which conveys or contains flammable fluid in a designated fire zone must be fire 

resistant, except that flammable fluid tanks and supports in a designated fire zone must be 

fireproof or be enclosed by a fireproof shield unless damage by fire to any non-fireproof part 

will not cause leakage or spillage of flammable fluid. Components must be shielded or located 

to safeguard against the ignition of leaking flammable fluid. 

(b) Subparagraph (a) of this paragraph does not apply to: 

(1) Lines, fittings and components which are already approved as part of a type certificated 

engine; and: 

(2) Vent and drain lines, and their fittings, the failure of which will not result in, or add to, 

a fire hazard. 

(c) All components, including ducts, within a designated fire zone must be fireproof if, when 

exposed to or damaged by fire, they could: 

(1) Result in fire spreading to other regions of the Airship, or

(2) Cause unintentional operation of, or inability to operate, essential services or 

equipment.

HCC.J1185 Flammable fluids

(a) Except for the integral oil sumps specified in HCC.J1013 (a), no tank or reservoir that is a 

part of a system containing flammable fluids or gases may be in a designated fire zone unless 

the fluid contained, the design of the system, the materials used in the tank, the shut-off 

means, and all connections, lines and controls provide a degree of safety equal to that which 

would exist if the tank or reservoir were outside such a zone. 
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(b) There must be at least 0.5 in (13 mm) of clear airspace between each tank or reservoir and 

each firewall or shroud isolating a designated fire zone. 

(c) Absorbent materials close to flammable fluid system components that might leak must be 

covered or treated to prevent the absorption of hazardous quantities of fluids. 

HCC.J1187 Drainage and ventilation of fire zones 

(a) There must be complete drainage of each part of each designated fire zone to minimize the 

hazards resulting from failure or malfunctioning of any component containing flammable 

fluids. The drainage means must be:

(1) Effective under conditions expected to prevail when drainage is needed; and 

(2) Arranged so that no discharge fluid will cause an additional fire hazard. 

(b) Each designated fire zone must be ventilated to prevent the accumulation of flammable 

vapors.

(c) No ventilation opening may be where it would allow the entry of flammable fluids, vapors, 

or flame from other zones.

(d) Each ventilation means must be arranged so that no discharged vapors will cause an 

additional fire hazard.

(e) Unless the extinguishing agent capacity and rate of discharge are based on maximum air 

flow through a zone, there must be a means to allow the crew to shut-off sources of forced 

ventilation to any fire zone except the engine power section of the nacelle and the combustion 

heater ventilating air ducts.

HCC.J1188 Ventilation 

Each compartment containing any part of the powerplant installation must have provision for 

ventilation to prevent the accumulation of flammable vapors.

HCC.J1189 Shut-off means 

(a) Each engine installation and each fire zone specified in HCC.J1181 (a)(5) and (a)(6) must 

have means to shut-off or otherwise prevent hazardous quantities of fuel, oil, and other 

flammable liquids from flowing into, within, or through any engine compartment, except that 

shut-off means are not required for:

(1) Lines, fittings, and components forming an integral part of an engine; and 

(2) Oil systems in which all components of the system in a designated fire zone, including 

the oil tanks, are fireproof or located in areas not subject to engine fire conditions. 

(b) The closing of the fuel shutoff valve for any engine may not make fuel unavailable to the 

remaining engines. 

(c) Operation of any shutoff means may not interfere with the later emergency operation of 

other equipment such as propeller feathering devices. 

(d) Each flammable fluid shut-off means and control must be fireproof or must be located and 

protected so that any fire in a fire zone will not affect its operation. 
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(e) No hazardous amount of flammable fluid may drain into the engine compartment after 

shutoff. 

(f) There must be means to guard against inadvertent operations of each shutoff means, and to 

make it possible for the crew to reopen the shutoff means in flight after it has been closed. 

(g) Each tank-to-engine shut-off valve must be located so that the operation of the valve will 

not be affected by powerplant or engine mount structural failure. 

(h) Each shut-off valve must have a means to relieve excessive pressure accumulation unless 

a means for pressure relief is otherwise provided in the system. 

HCC.J1191 Firewalls 

(a) Each engine, fuel-burning heater and other combustion equipment intended for operation 

in flight, and the combustion, turbine, and tailpipe sections of turbine engines must be isolated 

from the rest of the Airship by firewalls, shrouds, or other equivalent means. 

(b) Each firewall or shroud must be constructed so that no hazardous quantity of liquid, gas, 

or flame can pass from the engine compartment to other part of the Airship. 

(c) Each opening in the firewall or shroud must be sealed with close-fitting, fireproof 

grommets, bushings, or firewall fittings. 

(d) Each firewall and shroud must be fireproof and protected against corrosion. 

(e) Compliance with the criteria for fireproof materials or components must be shown as 

follows. 

(1) The flame to which the materials or components are subjected must be 2000 ± 150°F 

(1100 ± 65°C); 

(2) Sheet materials approximately 10 sq in must be subjected to the flame from a suitable 

burner; 

(3) The flame must be large enough to maintain the required test temperature over an area 

approximately 5 sq in. 

(f) Firewall materials and fittings must resist flame penetration for at least 15 minutes. 

(g) The following materials may be used in firewalls or shrouds without being tested as 

required by this paragraph: 

(1) Stainless steel sheet, 0.015 in (0.38 mm) thick. 

(2) Mild steel sheet (coated with aluminum or otherwise protected against corrosion) 0.018 

in (0.45 mm) thick.

(3) Terne plate, 0.018 in (0.45 mm) thick. 

(4) Monel metal, 0.018 in (0.45 mm) thick. 

(5) Steel or copper base alloy firewall fittings. 
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HCC.J1192 Engine accessory compartment diaphragm 

For air-cooled radial engines, the engine power section and all portions of the exhaust system 

must be isolated from the engine accessory compartment by a diaphragm that meets the firewall 

requirements of HCC.J1191.

HCC.J1193 APU Engine compartment 

(a) The APU engine compartment must be constructed and supported so that it can resist the 

vibration, inertia, and air loads to which it may be subjected in operation.

(b) APU engine compartment must meet the drainage and ventilation requirements of 

HCC.J1187. 

(c) On Airships with a diaphragm isolating the engine power section from the engine 

accessory section, each part of the accessory section compartment subject to flame in case of 

fire in the engine power section of the APU must: 

(1) Be fireproof; and 

(2) Meet the requirements of HCC.J1191. 

(d) Each part of the APU engine compartment subjected to high temperatures due to its 

nearness to exhaust-system parts or exhaust gas impingement must be fireproof. 

HCC.J1195 Fire extinguishing systems 

Fire extinguishing systems must be installed and compliance shown with the following. 

(a) Except for combustor, turbine, and tailpipe sections of turbine engine installations that 

contain lines or components carrying flammable fluids or gases for which a fire originating in 

these sections is shown to be controllable, a fire extinguisher system must serve each engine 

compartment. 

(b) The fire extinguishing system, the quantity of the extinguishing agent, the rate of 

discharge, and the discharge distribution must be adequate to extinguish fires. It must be 

shown by either actual or simulated flight tests that under critical airflow conditions in flight 

the discharge of the extinguishing agent in each designated fire zone specified in 

subparagraph (a) of this paragraph will provide an agent concentration capable of 

extinguishing fires in that zone and of minimizing the probability of re-ignition. An individual 

'one-shot' system may be used for fuel burning heaters, and other combustion equipment. For 

each other designated fire zone, two discharges must be provided each of which produces 

adequate agent concentration. 

(c) The fire extinguishing system for an APU compartment must be able to protect 

simultaneously each compartment of the APU area for which protection is provided. 

HCC.J1197 Fire extinguishing agents 

(a) Fire extinguishing agents must: 

(1) Be capable of extinguishing flames emanating from any burning fluids or other 

combustible materials in the area protected by the fire extinguishing system; and 

(2) Have thermal stability over the temperature range likely to be experienced in the 

compartment in which they are stored. 
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(b) If any toxic extinguishing agent is used, provisions must be made to prevent harmful 

concentrations of fluid vapors (which could occur from leakage during normal Airship 

operation or as a result of discharging the fire extinguisher on the ground or in flight) from 

entering any personnel compartment, even if a defect may exist in the extinguishing system. 

This must be shown by test except for extinguishing systems built into the personnel 

compartment where:

(1) 5 lb (2.3 kg) or less of carbon dioxide is available for discharge into personnel 

compartments under established extinguishing procedures, or 

(2) Protective breathing equipment is available for each flight crew member on flight deck 

duty. 

HCC.J1199 Extinguishing agent containers 

The following applies: 

(a) Each extinguishing agent container must be fitted with a pressure relief device to prevent 

the container from bursting through excessive internal pressures. 

(b) The discharge end of each discharge line from a pressure relief connection must be located 

so that discharge of the fire extinguishing agent does not damage the Airship. The line must 

also be located or protected to prevent clogging caused by ice or other foreign matter. 

(c) A means must be provided for each fire extinguishing agent container to indicate that the 

container has discharged or that the charging pressure is below the established minimum 

necessary for proper functioning. 

(d) The temperature of each container must be maintained, under intended operating 

conditions, to prevent the pressure in the container from 

(1) Falling below that necessary to provide an adequate rate of discharge; or 

(2) Rising high enough to cause premature discharge. 

(e) If a pyrotechnic capsule is used to discharge the extinguishing agent, each container must 

be installed so that temperature conditions will not cause hazardous deterioration of the 

pyrotechnic capsule. 

HCC.J1201 Fire extinguishing system materials 

The following apply: 

(a) No material in any fire extinguishing system shall be capable of reacting chemically with 

any extinguishing agent so as to create a hazard. 

(b) Each system component in an engine compartment must be fireproof. 

HCC.J1203 Fire detector system 

(a) There must be approved, quick acting fire or overheat detectors in each designated fire 

zone, and in the combustion, turbine, and tailpipe sections of turbine engine installations, in 

numbers and locations ensuring prompt detection of fire in those zones. 

(b) Each fire detector must be constructed and installed so that-
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(1) It will withstand the vibration, inertia, and other loads to which it may be subjected in 

operation and 

(2) There is a means to warn the crew in the event that the sensor or associated wiring 

within a designated fire zone is severed at one point, unless the system continues to 

function as a satisfactory detection system after the severing; and 

(3) There is a means to warn the crew in the event of a short circuit in the sensor or 

associated wiring within a designated fire zone, unless the system continues to function as 

a satisfactory detection system after the short circuit 

(c) No fire or overheat detector may be affected by any oil, water, other fluids or fumes that 

might be present. 

(d) There must be means to allow the crew to check, in flight, the functioning of each fire 

detector electric circuit. 

(e) Wiring and other components of each fire detector system in an engine compartment must 

be at least fire resistant. 

(f) No fire or overheat detector system component for any fire zone may pass through another 

fire zone, unless -

(1) It is protected against the possibility of false warnings resulting from fires in zones 

through which it passes; or 

(2) Each zone involved is simultaneously protected by the same detector and extinguishing 

system. 

(g) Each fire detector system must be constructed so that when it is in the configuration for 

installation it will not exceed the alarm activation time approved for the detectors using the 

response time criteria specified in the appropriate Technical Standard Order. 

HCC.J1207 Compliance 

Unless otherwise specified, compliance with the requirements of HCC.J1181 to J1205 must be 

shown by a full scale fire test or by one or more of the following methods: 

(a) Tests of similar powerplant configurations; 

(b) Tests of components; 

(c) Service experience of Airships or aircraft with similar powerplant configurations; 

(d) Analysis. 
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APPENDICES

APPENDIX A Tables and data 

Table 1 - Design maneuver conditions 

No Condition Speed Weight Attitude Thrust Control Surface 

Position 

Direction Rudder Elevator 

1 Level Flight VH Wt (2) Forward Neutral (2) 

2 Level Flight 0.71 VH Wl (2) Reverse Neutral (2) 

3 Nose Down VH W0 + 30° Forward Neutral (2) 

4 Nose Up VH W0 - 30° - Neutral (2) 

5 Descent & Pull-Up VH Wt (2) Forward Neutral (2) 

6 Turn Entry VH W0 Horizontal Forward Full Over Neutral 

7 Turn & Reverse VH W0 Horizontal Forward (3) Neutral 

8 Dive Entry VH W0 Horizontal Forward Neutral Full 

Down 

9 Climb Entry VH W0 Horizontal Forward Neutral Full Up 

10 Turn & Climb VH W0 Horizontal Forward Full Over Full Up 

11 Turn & Dive VH W0 Horizontal Forward Full Over Full 

Down 

12 Turn (1) W0 Horizontal Forward Full Over Neutral 

13 Turn Recovery (1) W0 Horizontal Forward (3) Neutral 

14 Turn Rec. & Climb (1) W0 Horizontal Forward (3) Full Up 

15 Turn Rec. & Dive (1) W0 Horizontal Forward (3) Full 

Down 

16 Light Flight VH (2) (2) Forward Neutral (2) 

Notes 

(1) Velocity values must be determined after speed is stabilized, but not before a steady state 

condition. 

(2) That necessary to produce maximum loading conditions. 

(3) Full rudder must be applied followed by full reverse rudder after 75° of turn. 
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Table 2 - Pilot Forces

Control Maximum 

Force or Torque

Minimum Force 

or Torque

(a) Elevator

Capstan wheel (1)

Wheel mounted on a column (symmetrical)

Wheel mounted on a column (unsymmetrical) (2)

Stick

167 lb f (745 N)

200 lb f (900 N)

-

167 lb f (745 N)

100 lb f (445 N)

100 lb f (445 N)

100 lb f (445 N)

100 lb f (445 N)

(b) Rudder

Rudder pedals (3)

Wheel mounted on a column (4)

Stick

200 lb f (900 N)

50 D in-lb (5)

(5.6 D Nm)

67 lb f (300 N)

130 lb f (580 N)

40 D in-lb (5)

(4.5 D Nm)

40 lb f (180 N)

(c) Wheels, levers and cranks operated by

- finger or wrist forces

- hand/arm force without support (seated/standing)

- hand/arm force with support (seated/standing)

33 lb f (145 N)

76 lb f (340 N)

133 lb f (590 N)

(d) Sidestick operated by one wrist (not arm)

for all components between and including the 

handle and its control stops

 - in x-direction

 - in y-direction

for all other components of the side stick control 

assy (excluding the internal components of the electrical 

sensor assy) to avoid damage as a result of an in-flight jam

 - in x-direction

 - in y direction

200 lb f (875 N)

100 lb f (435 N)

125 lb f (545 N)

50 lb f (220 N)

Notes 

(1) When a capstan wheel is mounted beside the pilot, the fore-and-aft force is applied to the 

highest point on the rim of the wheel. 

(2) The unsymmetrical force must be applied at one of the normal hand grip points on the control 

wheel. 

(3) If provided, since Airships may not have pedals mandatory. 

(4) When the rudder operating control is a wheel mounted on a column in front of the pilot, the 

loads must be applied tangentially to the rim of the wheel. 

(5) D is the wheel diameter (m). 
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Table 3 - Takeoff and landing conditions 

Condition Attitude Weight Shock Absorber Landing Gear Loads (3)

Extension Vertical Lateral Longitudinal 

(4) (2)(4) (2)(4)

Takeoff Level Wt static 1.5 Wsh - 0.275 Wsh

Level Landing Level Wl maximum n Wl - ±0.25 nWl

Level Landing Level Wl maximum n Wl - (1) 

Landing Level Wl static 1.5 Wsh 0.55 Wsh -

Side Drift 

Landing 

Level Wl maximum n Wl 0.55 n Wl -

Notes 

(1) This load is based upon spin-up or spring-back conditions. 

(2) Lateral and longitudinal loads act in a horizontal plane. 

(3) For landing gear equipped with dual wheels, use a 60/40 load distribution between wheels. 

(4) n is the limit vertical inertia load factor, at the C.G. of the Airship, selected under 

HCC.473(b). 
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Table 4 – Mooring and handling conditions

Conditions (6) Weight Wind Velocity Wind Angle 

Symmetrical Mooring

Unsymmetrical Mooring

Mast Handling-Heavy (3) 

Mast Handling - Equilibrium (3) 

Mast Handling - Override (4) 

Line Handling (3), (5) 

Line Handling (3), (5) 

Wt

Wt

Wt

W0

Wt

Wt

W0

70 knots 

70 knots

(1)

(1)

0

(1)

(1) 

0

(2)

(2)

(2)

0

(2)

(2) 

Notes 

(1) The maximum wind velocities VWG expected to occur during ground handling are selected by 

the designer and listed in the Airship operating limitations, but may not be less than 10 knots. 

(2) The wind angle must be determined from the lateral wind force and the longitudinal wind 

force assumed imposed on the envelope with maximum design gas pressure. These wind forces 

are based on an instantaneous directional change to either side. In the absence of a more rational 

analysis, a wind angle of 10° must be used. 

(3) An envelope of ground loads must be determined based on critical effective relative wind 

angles. 

(4) Loads must be determined based on a compressive force between mast and Airship resulting 

from a differential speed of 3 knots. 

(5) For nose lines, use wind angles determined for mooring conditions with line angles of 0°-

120° laterally with respect to a vertical plane through the Airship axis and at an angle of 30° 

below the horizontal plane through the Airship axis. For tail or after quarter lines, an envelope of 

ground loads must be determined, using wind angles determined for mast handling. In the 

absence of a more rational analysis, use line angles of 60°-120° laterally to the same reference 

planes as for the nose lines. Line angles selected must be listed in the Airship handling

procedures. 

(6) Compressive loads caused by elastic rebound of the Airship due to a sudden change in wind 

velocity must be considered for all applicable mooring conditions. 

Table 5 - General tolerances during flight testing 

see HCC.21 (d) 
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Table 6 - Maximum pilot forces 

Values in N (pound force) 

applied to the control as specified

Pitch Axis Yaw Axis

Temporary application

Stick 60 lb f (265 N) 30 lb f (135 N)

Wheel (applied to rim) 75 lb f (335 N) 60 lb f (265 N)

Capstan wheel 60 lb f (265 N) ---

Rudder pedal 150 lb f (670 N)

Prolonged application

Stick or wheel (applied to rim) 10 lb f (45 N) 5 lb f (22 N)

Capstan wheel 10 lb f (45 N) ---

Rudder pedal 20 lb f (90 N)

Table 7 - Ultimate inertia forces in units of gravity 

Upward 1.5

Downward 4

Forward 4

Rearward 4

Sideward 4

Table 8 – Noncritical castings

Casting factor Inspection 

2.0 or more 100% visual 

Less than 2.0 but more than 

1.5

100% visual, and magnetic particle or penetrant, or 

equivalent nondestructive inspection methods

1.25 through 1.50 100% visual, magnetic particle or penetrant, and 

equivalent nondestructive inspection methods
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Table 9 – Motion and effect of cockpit controls

Controls Motion and effect 

Pitch Rearward for nose up 

Yaw Right pedal forward for nose right, or, for wheel or stick control, 

right (clockwise) for right yaw

Throttle Forward to open

Trims control Rotate to produce similar rotation of the Airship about an axis 

parallel to the axis of the trim wheel

Landing gear Down to extend

Power/Thrust Forward to increase forward or upward thrust and rearward to 

increase rearward or downward thrust

Vectored thrust control In co-ordination with power/thrust controls, the motion of the 

vectoring controls must clearly indicate the direction of thrust

Propellers Forward to increase rpm

Table 10 – Minimum intensities in the horizontal plane position lights

Dihedral angle (light included) Angle from right or left of 

longitudinal axis, measured from 

dead ahead

Intensity (cd)

F (bow white) 0° to 110° 20

L and R

(forward and rearward red and green) 

0° to 10°

10° to 20°

20° to 110°

40

30

5

A (stern white) 110° to 180° 20

Table 11 – Minimum intensities in any vertical plane position lights

Angle above or below the horizontal plane Intensity (cd)

0°

0° to 5°

5° to 10°

10° to 15°

15° to 20°

20° to 30°

30° to 40°

40° to 90°

1.00

0.90

0.80

0.70

0.50

0.30

0.10

0.05
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Table 12 – Maximum intensities in overlapping beams

Overlaps Maximum Intensity (cd)

Area A Area B

Green in dihedral angle L

Red in dihedral angle R

Green in dihedral angle A

Red in dihedral angle A 

White in dihedral angle L 

White in dihedral angle R 

10

10

5

5

5

5

1

1

1

1

1

1

Note 

Area A includes all directions in the adjacent dihedral angle that pass through the light source 

and intersect the common boundary plan at more than 10° but less than 20°. Area B includes all 

directions in the adjacent dihedral angle that pass through the light source and intersect the 

common boundary plan at more than 20°. 

Table 13 – Minimum effective intensities for anti-collision lights

Angle above or below the horizontal plane Effective intensity (cd)

0° to 5°

5° to 10°

10° to 20°

20° to 30°

30° to 75°

400

240

80

40

20
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Table 14 – Strength values for high pressure pneumatic systems

Strength Value

Element of System Proof Ultimate Remarks 

Rigid pipes and ducts

Couplings

Flexible hoses

Return line elements 

1.5 PW

1.5 PW

2.0 PW

---

3.0 PW

3.0 PW

4.0 PW

1.5 Pf Pf The maximum pressure applied during failure 

conditions 

Components other 

than pipes couplings, 

ducts or pressure 

vessels 

1.5 PW 2.0 PW

Pressure vessels 

fabricated from 

metallic materials (For 

non-metallic materials 

see 14 CFR part

25.1438 

Pressure vessels 

connected to a line 

source of pressure 

Pressure vessels not 

connected to a line 

source of pressure e.g. 

emergency vessels 

inflated from a ground 

source 

3.0 PL or 

1.5 PL

2.5 PL or 

1.5 PL

4.0 PL or 

2.0 PL

3.0 PL or 

2.0 PL

The lower values are conditional upon 

justification by a fatigue endurance test from 

which a permissible fatigue life is declared, and 

upon the ultimate load test being made on the test 

specimen used for the fatigue life test.

The lower values are conditional upon 

justification by a life endurance test of a suitably 

factored permissible number of inflation/deflation 

cycles, including temperature fluctuation results 

in a significant pressure variation, and upon the 

ultimate load test being made on the test 

specimen used for the life endurance test. 

For all pressure vessels: 

(1) The minimum acceptable conditions for 

storage, handling and inspection are to be defined 

in the appropriate manual. See 14 CFR part 25 

appendix H.

(2) The proof factor is to be sustained for at least 

three minutes. 

(3) The ultimate factor is to be sustained for at 

least one minute. The factor having been 

achieved, the pressure vessel may be isolated 

from the pressure source for the remaining 

portion of the test period. 
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APPENDIX B Tearing strength test 

Material tearing strength test

(Applicable for non-rigid and semi-rigid Airships only) 

Scope -This test method is intended for use in determining the tearing strength of envelope fabric 

required by HCC.883(d). 

Specimen - The sample must consist of a 4 x 6 in (98 mm x 152 mm) sample having a 1.25 in 

(38 mm) wide slit made with a razor blade across the center of the sample at right angles to the 

longest dimension. 

Apparatus -The apparatus must be approved. 

Procedures -The specimen must be placed symmetrically in the clamps of the machine with the 

long dimension parallel and the short dimension at right angles to the direction of application of 

the load. The yarn running parallel to the long dimension must be aligned parallel with one 

outside edge of the front jaw of each clamp to ensure the same yarns being gripped in both 

clamps. The clamps must be 1 in (25.4 mm) wide and must grip the yarns that have been slit. 

The distance between clamps must be 3 in (76 mm) at the start of the test, with the slit in the 

specimen an equal distance from each clamp jaw. Breaking force must be applied to the 

specimen at such a rate that the pulling clamp will travel at a uniform speed of 12.0 ±0.5 in (305 

mm ±12.7 mm) per minute. After rupture of the specimen, the breaking force must be read from 

the dial, scale, or chart and the value recorded. Five specimens in both the warp and woof (fill) 

directions must be tested and results reported for each fabric type. 

Result - The tearing strength value [N/mm] is the average load of the highest recorded peaks of 

the five specimens. 

Acceptance criteria (pass - fail criteria) - The limit design loads of the envelope must not 

exceed the result of the tested material strength value corresponding. 
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APPENDIX C Definitions and abbreviations 

General Definitions and Acronyms

TERM DEFINITION 

AC Advisory Circular

ACLS Air Cushion Landing System

Aerodynamic trim When all aerodynamic forces plus static lift force are exactly in line 

vertically with the center of gravity without control input by the pilot. 

AFM Airship Flight Manual

Airship A controllable, engine-driven lighter-than-air aircraft

APU Auxiliary Power Unit

ATC Air Traffic Control

Back-up system A second system with or without reduced system capability to 

function as a substitute for an original system, when this fails. 

Ballast, disposable Ballast to be dropped or dumped or jettisioned during flight to adjust 

c.g. or lighten the Airship due to a designated procedure. 

Ballast, fixed To be intended to adjust the Airships balance to achieve defined c.g. 

due to design tolerance in general or production tolerance on a 

specific production Airship. 

Ballast, removable Removable on ground. Thus to prepare the Airship for a certain flight 

mission or movable during flight within the Airship to adjust c.g. 

Ballonet A flexible and collapsible air cell contained within the envelope for 

the purpose of compensating for gas volume changes, maintaining 

internal pressure in the envelope, and assisting in trimming the 

Airship. 

BTPD Body Temperature, Ambient Pressure, Dry

Car Component or structure attached to or suspended from the envelope or 

the structure in- or outside of the envelope for carrying crew members, 

passengers, cargo or propulsion systems or other devices 

Cargo Payload such as freight, bulk cargo or unit load cargo. 

cd Candles

Center of buoyancy The point within the Airship where the buoyancy is assumed to be 

acting on. 

Center of gravity The point in which the mass of the Airship is assumed to be 

concentrated. 

CFR Code of Federal Regulations

Condition A failure, ambient, environmental, event condition, not a capability of 

the Airship. 

Conventional If similar design already approved or experienced otherwise. 

Conventional landing

gear 

Landing gear arrangement is considered as conventional if it consists 

of a single wheel, or twin co-axial wheels, or laterally separated 

wheels with or without shock absorbers with wheels and brakes 

located at the bottom of the Airships hull or keel or car structure. 

CRI Certification Review Item 
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TERM DEFINITION 

Critical function A function, the failure of which would prevent continued safe flight 

and landing of the Airship 

CVR Cockpit Voice Recorder

Defined Defined as/or designed for the product 

Density Density of pure gases at standard sea level atmospheric condition of 

1.01325 x 103 Pa (29.92 in Hg) pressure and 15°C (59°F) temperature

Designated Designated as/or designed for the product 

Desired Desired for the product 

DOP Design Operating Pressure 

Dry Air ρ=1.2250 kg/m3 (0.07647 lb/ft3)

Dry Helium ρ=0.1689 kg/m3 (0.01054 lb/ft3)

Dual redundant Parallel and independent systems. In case of failure of one system 

automatic detection and transition to the parallel system without 

action of the operator. The performed transition must be indicated by 

optical means 

Dual system Two similar or dissimilar systems used (not in a failure case only) as a 

redundant or alternative means with each system having full 

capability, but not a backup system. The independence will be very 

high 

EAS Equivalent Airspeed 

EEC Electronic Engine Control

EFIS Electronic Flight Instrument System

EMI Electromagnetic Interference

Envelope For a non-rigid or semi-rigid Airship: the main body or hull of which 

the shape is maintained by internal pressure. for a rigid Airship: a skin 

or cover around the airframe defining together the external shape of 

the Airship 

Equilibrium Zero static heaviness. The static lift force resulting from buoyancy is 

equal to gravity force. All aerodynamic forces are zero. Nearequilibrium is the capability of achieving zero static heaviness 

resulting in zero vertical air speed during normal flight operations 

Essential function A function, the failure of which would reduce the capability of the 

Airship or the ability of the crew to cope with adverse operating 

conditions 

External load A load attached to the Airship but not enclosed by any Airship 

structure 

FAA Federal Aviation Administration

FADEC Full Authority Digital Engine Control

FDR Flight Data Recorder

FHA Functional Hazard Assessment

Fixed thruster The angle of the thrust is fixed as a normal mode of operation. It 

comprises the thruster drive, thruster control system 

FS Factor of Safety
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TERM DEFINITION 

Gas cell A flexible and collapsible cell containing the lifting gas within the 

airframe or envelope of an Airship 

Grip mode ACLS has fans removing air from inside landing pads creating a 

suction which holds the airship stationary to the surface

Ground handling Condition under which external loads are applied to the Airship by 

ground crews and/ or mechanical equipment to control the movement 

of the Airship on the ground 

Ground operation Ground handling of the Airship already on a mast, moored/tied to the 

ground equipment, or parked. Flight crew is typically not required to 

perform the operation. Typical operations are hangar exit, moving the 

Airship, Airship masted or moored and maintenance 

HCC Hybrid Certification Criteria

Head-over If the masted Airship turns with the unmoored tail up vertically 

unintended due to gust or balance conditions. 

HIRF High Intensity Radiated Fields 

Hybrid airship An airship in the shape of a lifting body using aerodynamic lift in 

combination with air displacement and vectored thrust to generate the 

vehicle’s lift

ICA Instructions for Continued Airworthiness 

IFR Instrument Flight Rules

Keel Component or structure attached to or suspended from the envelope or 

the structure in- or outside of the envelope for carrying crew members, 

passengers, cargo or propulsion systems or other devices 

LIM Limit Load

LOTC Loss Of Thrust Control

LOPC Loss Of Power Control

Mass Definitions are stated in HCC.25 and 29

Masting Ground handling considered in flight until placing an Airship on a 

mast. Flight and ground crew is typically required to perform the 

operation 

Maximum altitude The maximum atmospheric ceiling altitude the Airship can reach 

pending on environmental conditions to Airship and equipment. 

Minor crash Emergency landing condition under which the occupant protection can 

be assured reliably

Mooring Ground handling consisting of tying the airship to the ground. Ground 

crew is typically required to perform the operation

Non-rigid airships Consisting of an envelope, the shape and stiffness of which is 

maintained by the lifting gas contained within it pressurized above 

ambient

Parking Airship stopped with the ACLS in the grip mode, common mode for 

loading and unloading hybrid airship
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TERM DEFINITION 

Pressure height Or ceiling height means the height at which the ballonets are fully 

deflated or where the gas cells are inflated to limit pressure. This 

height is variable but not to be exceeded without over-pressure or 

venting of the lifting gas.

Primary structure The envelope and rigid structure, if provided and carries the critical 

and essential loads. 

Privacy cabin A self contained cabin, which is indispensable for the occupants 

seclusion on long term flights 

Provided A capability of the Airship if desired or designated, but not a 

condition. 

Redundancy A dual, second or back-up system with no further specification. 

Rigid airships Consisting of an airframe, covered with a skin or envelope 

determining the external shape, carrying all heavy components and 

useful load. The lifting gas is contained within one or more gas cells

RPM Revolutions Per Minute

Secondary control All other controls except primary controls, i.e. also a trim system used 

for control of the Airship. 

Specified Defined. 

Starting point A term used in connection with the determination of takeoff 

performance; it is the point on the takeoff surface from which the tail 

point of a stationary Airship commences the takeoff maneuver. 

Static heaviness Difference between Airship mass and static lift. Ship downwards 

means static heaviness. 

Static lift The difference between the weight of air displaced by the Airship and 

the weight of the lifting gas.

Static lightness Difference between Airship mass and static lift. Ship upwards means 

static lightness. 

Static trim If the center of gravity is exactly below the center of buoyancy. 

Semi-rigid airships Consisting of an envelope, the shape of which is maintained by the 

lifting gas contained within it pressurized above ambient, stiffened 

with a structure attached to it

Technique The capability of the Airship in conjunction with a practical approved 

procedure for crew. 

Thruster drive system The mechanical linkage such as torque shafts, gear boxes and clutches 

to drive any thrust system. 

Trim height The height at which one of the ballonets is empty and the Airship is 

still in static trim. Above trim height, the Airship is out of static trim. 

ULT Ultimate load

Useful load All variable loads including cargo, ballast, passengers, and airship fuel

Unit lift The value used should be identified in the analysis of the design. In 

the absence of a rational analysis, 9.975 N/m3 (0.0635 lb/ft3) should be 

used for helium (96% purity)

Unit load device A unit load device to be restrained itself such as a cargo container, but 

not unrestrained bulk. 
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TERM DEFINITION 

UV Ultra-Violet

Variable angle thruster Or vectored thruster means the angle respective direction of the thrust 

is variable as a normal mode of operation. It comprises the thruster 

drive, the vectoring and thruster control system. 

VFR Visual Flight Rules

Virtual inertia Inertia added to a system resulting from changing momentum in the 

surrounding air during acceleration or deceleration of the Airship. As 

a property of the flow field itself, it should not be confused with 

aerodynamic drag or entrained air in the wake. 
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Abbreviations and Symbols 

Abbreviations and symbols in the HCC are in accordance with Title 14 of the Code of Federal 

Regulations. Symbols not specified by Title 14 are listed below. Speeds are equivalent airspeeds 

(EAS) unless indicated otherwise. 

α angel of attack

D dequivalent

f envelope ratio

H gust gradient length

Ie effective intensity

I(t) instantaneous intensity as a function of time

k limit hinge moment factor due to ground gust

L length of the airship

lR mean chord of control surface aft of the hinge line

m maximum aerodynamic bending moment

MR limit hinge moment

n limit vertical inertia load factor at the C.G. of the airship

Pf the maximum pressure applied during failure conditions

PL the limit pressure is the anticipated maximum pressure in service acting on a pressure 

vessel, including the tolerances and possible pressure variations in normal operating 

modes but excluding transient pressures

PW the working pressure is the maximum steady pressure in service acting on the element 

including the tolerances and possible pressure variations in normal operating modes but 

excluding transient pressures

q dynamic pressure

r density of air

SR area of the control surface aft of the hinge line

V total envelope volume

v airship equivalent speed

VRA maximum speed for flight in rough air

VWG design max. wind velocity on ground for takeoff, landing, ground handling and grip mode

VWT design wind speed for the Airship in grip mode for loading/unloading or 

boarding/unboarding. 

VWM design wind speed for moored Airship 

VB design airspeed for maximum gust operating or encounter speed 

VBmin design airspeed minimum for maximum gust intensity

VCD maximum climb dive speed 

VMO max. operating speed 

VVO max. thrust vector operation speed 

VH max. horizontal speed 

VHh design maximum level flight speed (heavy) 

VA design maneuver speed (reserved) 

VAM minimum aerodynamic control speed. 

VLE max. speed landing gear or ACLS extended 
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VLO max. landing gear or ACLS operating speed 

VMC min. control speed with the most critical engine inoperative but maintaining control of the 

Airship is still possible 

VCD design climb/dive airspeed 

u gust shape and intensity

Um gust velocity

Wm minimum design equilibrium mass

W0 max. design equilibrium mass, equaling max. design static lift 

Wsh max. design static heaviness 

Wsl max. design static lightness 

Wtoh max. takeoff static heaviness 

Wl max. landing mass 

Wt max. takeoff mass (W0+Wtoh) 

Wu max. useful load (cargo, ballast, airship fuel, passengers)

X gust penetration distance