**AIRCRAFT GENERAL**

**Table of contents**

## General 2

**Limitations 3**

**Engines 5**

**Propellers 9**

**Electrical System 10**

**Fuel System 12**

**Hydraulic System 13**

**Flight Controls 14**

**Ice and Rain Protection 15**

**Oxygen System 17**

**Ventilation and Heating 17**

**General**

A. Dimensions

1\. Wing Span 65 feet, 0 inches

2\. Height 18 feet, 7 inches

3\. Length 51 feet, 9 inches

B. Engines- Pratt and Whitney PT6A-27 (Installed on N141Z)

PT6A-34 (Installed on N143Z)

C. Propellers- Hartzell

1\. Constant speed

2\. Full feathering and reversing

D. Fuel

1\. Commercial grades- Jet A, Jet A-1, Jet B

2\. Military grades- JP-4, JP-5, JP-8

3\. System Capacity 380 gallons useable

E. Oil- Total capacity 9.2 quarts Exon 2380

F. Maximum Certification Weights

1\. Ramp weight 12,500 pounds

2\. Takeoff 12,500 pounds

3\. Landing 12,300 pounds

4\. Rear baggage compartment 500 pounds

5\. Nose baggage compartment 300 pounds

6\. Cabin floor loading 200 pounds/sq ft

7\. Baggage floor loading 100 pounds/sq ft

**Limitations**

A. Power plant PT6A-27 installed on N141Z

Engine Operating Limits

+-----------+-------+-------+--------+-----+-------+-------+--------+
| Power     | SHP   | T     | M      | Ng  | Np    | Oil   | Oil    |
|           |       | orque | aximum | (2) | (1) % | P     | Temp.  |
| Setting   |       | PSI   | ITT    | %   | RPM   | ress. | (C)    |
|           |       | (1)   | (C)    | RPM |       | PSI   | (4)    |
|           |       |       |        |     |       | (3)   |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Takeoff   | 620   | 50    | 725    | 10  | 96    | 8     | 10-99  |
| Max cont  |       |       |        | 1.5 |       | 0-100 |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Max climb | 620   | 50    | 695    | \(  | 96    | 8     | 0-99   |
| Max       |       |       |        | 5\) |       | 0-100 |        |
| cruise    |       |       |        |     |       |       |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Idle      |       |       | 660    |     |       | 40    | -40-99 |
|           |       |       | (6)    |     |       | min.  |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Starting  |       |       | 1090   |     |       |       | -40    |
|           |       |       | (7)    |     |       |       | min.   |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Transient |       |       | 825    | 10  | 110   |       | 0-99   |
|           |       |       | (7)    | 2.6 |       |       |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Max       | 620   | 50    | 725    | 10  | 91+1  | 8     | 0-99   |
| reverse   |       | (8)   |        | 1.5 |       | 0-100 |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+

\(1\) Maximum permissible sustained torque is 50 psi.

\(2\) For every 10 C below -30 C ambient temperature, reduce maximum
allowable Ng by 2.2%

\(3\) Normal oil pressure is 80 to 100 psi at gas generator speeds above
72% with oil temperature between 60 and 70 C. Oil pressures below 80 psi
are undesirable and should be tolerated only for the completion of the
flight, preferably at a reduced power setting. Oil pressures below
normal should be reported as an engine discrepancy and should be
corrected before the next takeoff. Oil pressures below 40 psi are unsafe
and require that either the engine be shut down or a landing be made as
soon as possible using the minimum power required to sustain flight.

\(4\) For increased service life of the engine (i.e., the time between
oil changes), an oil temperature between 74 C and 80 C is recommended. A
minimum oil temperature of 55 C is recommended for fuel heater operation
at takeoff power.

\(5\) Climb and cruise power settings should be achieved by use of power
setting charts.

\(6\) At 51% rpm (Ng) minimum. Increase Ng as required to maintain idle
temperature limit.

\(7\) These values are time-limited to two seconds.

\(8\) Reverse power operation is time limited to one minute.

**Limitations**

A. Powerplant PT6A-34 installed on N143Z

Engine Operating Limits

+-----------+-------+-------+--------+-----+-------+-------+--------+
| Power     | SHP   | T     | M      | Ng  | Np    | Oil   | Oil    |
|           |       | orque | aximum | (2) | (1) % | P     | Temp.  |
| Setting   |       | PSI   | ITT    | %   | RPM   | ress. | (C)    |
|           |       | (1)   | (C)    | RPM |       | PSI   | (4)    |
|           |       |       |        |     |       | (3)   |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Takeoff   | 620   | 50    | 790    | 10  | 96    | 8     | 10-99  |
| Max cont  |       |       |        | 1.5 |       | 5-105 |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Max climb | 620   | 50    | 765    | \(  | 96    | 8     | 0-99   |
| Max       |       |       |        | 5\) |       | 5-105 |        |
| cruise    |       |       |        |     |       |       |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Idle      |       |       | 685    |     |       | 40    | -40-99 |
|           |       |       | (6)    |     |       | min.  |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Starting  |       |       | 1090   |     |       |       | -40    |
|           |       |       | (7)    |     |       |       | min.   |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Transient |       |       | 850    | 10  | 110   |       | 0-99   |
|           |       |       | (7)    | 2.6 |       |       |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+
| Max       | 620   | 50    | 725    | 10  | 91+1  | 8     | 0-99   |
| reverse   |       | (8)   |        | 1.5 |       | 5-105 |        |
+-----------+-------+-------+--------+-----+-------+-------+--------+

\(1\) Maximum permissible sustained torque is 50 psi.

\(2\) For every 10 C below -30 C ambient temperature, reduce maximum
allowable Ng by 2.2%

\(3\) Normal oil pressure is 85 to 105 psi at gas generator speeds above
72% with oil temperature between 60 and 70 C. Oil pressures below 85 psi
are undesirable and should be tolerated only for the completion of the
flight, preferably at a reduced power setting. Oil pressures below
normal should be reported as an engine discrepancy and should be
corrected before the next takeoff. Oil pressures below 40 psi are unsafe
and require that either the engine be shut down or a landing be made as
soon as possible using the minimum power required to sustain flight.

\(4\) For increased service life of the engine (i.e., the time between
oil changes), an oil temperature between 74 C and 80 C is recommended. A
minimum oil temperature of 55 C is recommended for fuel heater operation
at takeoff power.

\(5\) Climb and cruise power settings should be achieved by use of power
setting charts.

\(6\) At 51% rpm (Ng) minimum. Increase Ng as required to maintain idle
temperature limit.

\(7\) These values are time-limited to two seconds.

\(8\) Reverse power operation is time limited to one minute.

**Limitations (continued)**

B. Airframe

1\. Vmc Flaps 10 to 20 degrees 64 KIAS

2\. Vmc Autofeather Inoperative 68 KIAS

3\. Vmo MSL to 6700 MSL 166 KIAS

4\. Vmo To 10000 MSL 156 KIAS

5\. Vmo To 15000 MSL 141 KIAS

6\. Vmo To 20000 MSL 126 KIAS

7\. Vmo To 25000 MSL 112 KIAS

8\. Vfe 0 to 10 degrees 100 KIAS

9\. Vfe 10 to 37.5 degrees 93 KIAS

10\. Va 132 KIAS

11\. Demonstrated crosswind 20 Knots

C. Starter

1\. 25 seconds ON, 60 seconds OFF

2\. 25 seconds ON, 60 seconds OFF

3\. 25 seconds ON, 30 **minutes** OFF

D. Use of Aviation Gasoline

1\. Limited to 150 hours between engine overhauls

2\. Limited to 8000 feet MSL without boost pumps

3\. Crossfeed capability for single engine operation only

4\. Limited to 100 octane (not above 15000 ft MSL)

E. Maximum altitude is 25000 ft MSL

F. Tire pressures

1\. Nose wheel......32 PSI

2\. Main gear......\...38 PSI

**Engines**

A. United Aircraft of Canada PT6A-27 (680 SHP) or PT6A-34 (750 SHP)

1.  Reverse flow free turbine engine flat rated to 620 SHP in this
    installation

2\. Compressor

a\. Three-stage axial

b\. One-stage centrifugal

c\. Driven by single stage reaction turbine

d\. One interstage bleed valve

3\. Turbine

a\. Single-stage compressor turbine drives compressor and accessory
section (N1)

b\. Single-stage power turbine drives propeller shaft (Np)

c\. Power turbine is free air (no mechanical connection)

4\. Combustion Chamber

a\. Singular annular unit

b\. 14 fuel nozzles (10 primary, 4 secondary)

c\. Two igniters per engine are used to start combustion

d\. Pneumatic fuel control schedules fuel flow set by power lever

4\. Accessory drive at aft end of engine drives:

a\. Fuel pump

b\. Fuel control unit

c\. Oil pump

d\. Starter/generator

e\. Tachometer (N1)

5\. Gear reduction box at forward end of engine drives:

a\. Propeller

b\. Prop Np

c\. Primary propeller governor

d\. Overspeed governor

e\. Fuel topping governor

f\. Gear box speed is 33000 RPM at 101.5%

B. Torquemeter

1\. Hydro mechanical measuring device consisting of:

a\. Ring gear and case

b\. Torquemeter cylinder, piston, and valve plunger

c\. Differential pressure sensor and servo transmitter

d\. Servo indicator (Torque gauge calibrated to read PSI)

2\. Propeller torque increase causes:

a\. Ring gear moves forward

b\. Trapped oil moves piston

c\. Piston drives servo transmitter

d\. Transmitter signals servo indicator (Torque gauge)

**Engines (continued)**

C. Propulsion System Controls

1\. Power levers (these control engine power)

a\. Operate fuel control unit (FCU)

b\. When rotated they disengage mechanical locks allowing power control

through beta and reverse ranges

c\. CAUTION; Do not move into reverse position when engines are not
running

2\. Condition Levers

a\. Control flow of fuel at FCU

b\. Select fuel cut off

c\. Low idle at 50% Ng; no high idle function

3\. Propeller levers

a\. Control propellers through primary prop governor

D. Engine Instrumentation

1\. Interstage Turbine Temperature (ITT)

a\. Ring of eight thermocouples around power turbine inlet

b\. Trim probe provides correction for manufacturing tolerances

2\. Gas Generator (N1)

a\. Tach generator on accessory gearbox (self powered)

3\. Torque Gauge

a\. Torque is sensed at first stage ring gear, which is mounted in the
gear box with

a helical cut spline so that increased torque load causes the ring gear
to move aft.

This aft motion is resisted by a piston containing oil pressure. The oil
pressure

is regulated and directly proportional to the torque. Torque is sensed
using a

26 volt AC transducer.

b\. Limitations

1\. Maximum torque 50 PSI

2\. Max torque during acceleration 68.8 PSI for 2 seconds

3\. Max torque in reverse 50 PSI for 1 minute

4\. Fuel Flow Indicator

a\. Marked in PPH x 100

b\. Powered by 400 cycle 26 VAC

**Engines (continued)**

5\. Oil Pressure Gauge

a\. Powered by 26 VAC

b\. Minimum oil pressure at idle 40 PSI

c\. Green Arc for --27s is 80-100 psi, for --34s is 85-105 psi.

6\. Oil Temperature Gauge

a\. 28 volt DC powered

b\. Minimum temperature, start: -40C

c\. Minimum idle -40C, maximum 99C

d\. Minimum take-off 10C. maximum 99C

e\. Minimum cruise and climb 0C, maximum 99C

E. Engine Lubrication

1\. The 1.5 gallons of Exon 2380 turbine oil provide lubrication,
cooling. propeller

control, torque indication, and the heating of fuel.

2\. Oil tank capacity is 2.3 gallons. The oil pressure pump, regulator,
and oil filter

with bypass are located in this tank

3\. Scavenge Pumps (4 per engine)

a\. Return oil from the compressor and turbine bearings to the accessory
gear case

where the air is separated and dumped overboard.

b\. Oil from the accessory gear case is returned to the tank via the
fuel heater and

the oil cooler.

c\. Oil from the propeller gear box is returned to the tank via the oil
cooler.

F. Fire Detection and Suppression

1\. Detection: 4 heat sensitive detectors per engine- one in accessory
section and

one at the C flange. The bimetal elements trigger warning lights on
T-handles

and warning bell behind pilot\'s head. Bell is cancelable.

2\. Suppression: Pulling the T-handle discharges the contents of the
associated fire

extinguisher. One shot per engine.

**Propellers**

A. Hartzell Propeller

1\. Full feathering, reversing, all metal

2\. Constant speed

3\. Counter-weighted

5\. Controlled with propeller levers using engine oil boosted by the
pump

in the engine driven propeller governer

B. Centrifugal counter-weights, assisted by feathering spring, move
propeller blades

To low RPM (high pitch) and into feather

C. Governor boosted engine oil pressure move propellers to high RPM,
(low pitch)

Hydraulic stop and reverse position

D. Primary Governor

1\. Mounted to the top of the gear reduction housing

2\. Controls prop through entire range (+17 to +87 degrees of blade
angle)

3\. Propeller levers control RPM through this governor

E. Overspeed Governor

1\. If the primary governor fails and the prop exceeds 96%, the
overspeed governor

dumps oil from prop dome to limit Np to 101.5%

2\. Solenoid actuated by overspeed governor test switch resets overspeed
to 70% for

testing purposes

F. Fuel Topping Governor

1\. Prevents overspeed in the event that the prop should stick or move
too slowly during

transient or failure of the primary governor or the hydraulic low pitch
stop

2\. Limits at 102% Np or or 6% above selected Np by limiting fuel flow

3\. In reverse range the fuel topping governor is reset to 4% below
selected prop speed to

prevent governor interaction.

G. Autofeather System

1\. Dumps oil from prop dome

2\. Feathering spring and counterweights drive blades into feather

3\. System is armed when autofeather switch on and power levers set
above 88% Ng

4\. Autofeather lights indicate when system is armed

5\. Dump valve is controlled by sensing torque differential

6\. If one engine starts to feather, the other engine autofeather system
is disarmed

H. Low Pitch Stops

1\. Mechanical/hydraulic stop

2\. Allows blades to rotate beyond low pitch position and into reverse
when selected

3\. Beta and reverse blade angles are provided by adjusting low pitch
stop

4\. Blade angle is controlled by power levers in reverse range

**Electrical System**

The Twin Otter electrical system functions primarily on 28 volt DC
power. AC power is used for some avionics, the fuselage fuel quantity
indicating system, and some engine instruments.

The electrical system normally consists of two batteries (main and
auxiliary), two starter-generators, two inverters, provisions to connect
ground power, and devices for indication, regulation, and control. The
main battery is used to start the engines and for emergency in-flight
backup power. The auxiliary battery supplies power to the engine
igniters and start control relays.

The aircraft has two inverters. Only one at a time is used to supply the
required AC power. Commonly, but not always, DC circuits are protected
by circuit breakers, and AC circuits are protected by fuses.

A.  Main Battery

    1.  One 24 VDC, 42 amp-hour lead acid battery

    2.  Located under floor of rear baggage compartment

    3.  Supplies power to electrical system when DC MASTER is ON, and
        the BATTERY/EXTERNAL switch is BATTERY

    4.  Battery temperature monitor located under right instrument panel

    5.  Hot battery bus, has breaker panel on aft cabin wall, controls
        passenger door entrance lighting and baggage compartment lights.

B.  Auxiliary Battery

    1.  24 VDC, 3.6 amp-hour lead acid

    2.  Located right forward wall of rear baggage compartment

    3.  Provides power for start control relays and engine igniters

    4.  Recharged whenever a generator is on line

C.  External Power

    1.  Receptacle located left side forward of rear baggage compartment
        door

    2.  Supplies power when DC MASTER is ON and BATTERY/ EXTERNAL switch
        is EXTERNAL

    3.  No cockpit indication that external power source has been
        disconnected

D.  DC MASTER Switch

    1.  Controls power to all busses except Hot Battery Bus ( in
        conjunction with the BATTERY/EXTERNAL Switch and the BUS TIE
        Switch)

E.  BATTERY/EXTERNAL Switch

    1.  OFF -- No power

    2.  BATTERY -- power supplied from batteries or generators only
        (normal position in flight to allow the batteries to recharge

    3.  EXTERNAL -- power from external source only ( de-energizes the
        main battery relay and aux battery relay. If a generator is
        selected online now, the

> External power relay removes external power.

Note: It is not possible to charge the aircraft battery with power
supplied to the External Power Receptacle.

F.  BUS TIE Switch

    1.  Normally closed (NORMAL position)

    2.  Parallels generator output

    3.  When in the OPEN position:

        a.  Left bus powered by left battery and left generator

        b.  Right bus powered by right generator

G.  Power Distribution and Control Box

    1.  Located in right side cabin roof

    2.  Provides reverse current protection

    3.  Provides current limiting

    4.  Provides overvoltage protection

    5.  Windshield heat CBs located here

    6.  Location of Reverse Current Relays (RCRs) which:

        a.  Connect battery or external power to Starter/Generator
            during start

        b.  Connect generator output to DC busses

H.  Voltage Regulators

    1.  Located right side forward wall of rear baggage compartment

I.  Starter/Generators

    1.  28.5 VDC

    2.  200 amp maximum output

    3.  One per engine in accessory section

J.  Voltmeter

    1.  Connected to left DC bus

    2.  Indicates highest available voltage supplied to left DC bus,
        regardless of the power source

K.  Loadmeter

    1.  Normally reads battery load

    2.  Toggle switch to right to read right generator load

    3.  Toggle switch to left to read left generator load

    4.  Reads 0 to 1.0

        a.  Limit is .5 generator load at idle Ng

        b.  Limit is .8 generator load for ground operations

        c.  Limit is 1.0 generator load in flight

L.  AC system

    1.  2 inverters

    2.  Supply 115 volt and 26 volt 400 Hz single phase AC power

    3.  #1 inverter powered from left DC bus

    4.  #2 inverter powered from right DC bus

    5.  AC powers:

        a.  Fuel flow gauges

        b.  Oil pressure gauges

        c.  Fuel quantity indicators

        d.  Torque pressure gauges

        e.  Both attitude indicators

        f.  Directional gyros, some flight director functions

**Fuel System**

A. Fuel Storage

1\. Total capacity is 380 gallons in two tanks located in belly of
aircraft

2\. Forward tank

a\. Capacity 182 gallons

b\. Consists of 4 nylon rubber cells- 3 feeder cells and 1 collector
cell

c\. Collector cell has two internal 28 VDC powered boost pumps, 1
primary

and 1 secondary

d\. Forward tank normally feeds right engine

3\. Aft tank

a\. Capacity 198 gallons

b\. Consists of 4 nylon rubber cells- 3 feeder cells and 1 collector
cell

c\. Collector cell has two internal 28 VDC powered boost pumps, 1
primary

and 1 secondary

d\. Aft tank normally feeds the left engine

B. Fuel Indication Systems

1\. Fuel quantity gauges

a\. Capacitance-resistance type

b\. 115 VAC powered

c\. Shows pounds of useable fuel

2\. Fuel Low Level Caution Lights

a\. Located on Central Warning Panel (CWP)

b\. FWD FUEL LOW LEVEL comes on with 75 pounds useable fuel remaining

c\. AFT FUEL LOW LEVEL comes on with 110 pounds useable fuel remaining

3\. Fuel Flow Indicators

a\. Gauges on instrument panel powered by 26 VAC

b\. Gauges read pounds per hour (PPH)

C. Fuel Distribution

1\. Boost pumps

a\. Submerged in collector tanks

b\. Supply low pressure fuel from tank through fuel strainer, fuel flow
transmitter,

oil to fuel heater and emergency shut-off valve to the high pressure
fuel pumps

c\. If primary boost pump fails, the secondary pump automatically takes
over via

change over circuitry

2\. High pressure fuel pumps

a\. One per engine on accessory gear drive

b\. Supply high pressure fuel (75 PSI @ 12% Ng, 850 PSI @ 101.5% Ng)

D. Cockpit Fuel Controls

1\. Fuel levers

2\. Fuel Emergency Shut-off Valves

a\. Controlled by switches on instrument panel near Fire T-handles

3.  Fuel Tank Selector- NORM, BOTH ON AFT, or BOTH ON FWD

**Hydraulic System**

A. Hydraulic System Components

1.  Located in the hydraulic bay, left side under cockpit door

2.  Electric motor and pump

    a.  Motor powered from left DC bus, guarded by 35A circuit breaker

    b.  Drives gear type hydraulic pump

    c.  Amber Light 'HYD PUMP C/B OPEN' near pilot's airspeed indicator

3.  Pressure Switch

    a.  operates relay located near main distribution bus

    b.  turns pump off at 1525-1625 PSI

    c.  turns pump on at 1225-1325 PSI

4.  Reservoir

    a.  unpressurized

    b.  has cap and dipstick

    c.  fluid used is MIL-H-5606

5.  Accumulators

    a.  System Accumulator

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1.  750 PSI nitrogen precharge

2.  gauge on instrument panel and in hydraulic bay

3.  Serves wheel brakes, flaps, and nose wheel steering

    a.  Brake Accumulator

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1.  750 PSI nitrogen precharge

2.  gauge on instrument panel and in hydraulic bay

3.  Serves wheel brakes only

B. Hand Pump

1.  double- acting hand operated pump

2.  located on cockpit floor near pilot's left foot

3.  pump handle stowed in cockpit

4.  provides a back-up source of pressure in event of electric pump
    failure

C. Hydraulic Subsystems

1.  Wheel brakes- see Landing Gear

2.  Nose wheel steering- see Landing Gear

3.  Flaps- see Flight Controls

# Flight Controls

A. Primary Controls

1.  Ailerons

    a.  Controlled by cables, pulleys, and mechanical linkage

    b.  Dual Y design control column

    c.  Control wheels are spring loaded to neutral

    d.  Each aileron has geared servo tab

    e.  Stall fences enhance effectiveness at slow airspeeds

    f.  Ailerons are attached to outboard foreflaps

    g.  Extend down and back symmetrically as flaps extend

    h.  Degree of aileron movement relative to control wheel movement

> increases the more the flaps are extended

2.  Elevators

    a.  Controlled by cables, pulleys, and mechanical linkage

    b.  Have no geared servo tab

    c.  Wiper seals on elevator leading edges enhance handling at slow
        airspeeds

3.  Rudder

    a.  Controlled by cables, pulleys, and mechanical linkage

    b.  Has geared servo tab

    c.  Wiper seal on leading edge preserves effectiveness at large
        angles

> of deflection

d.  Vortex generators enhance rudder effectiveness at slow airspeeds

B. Trim Systems

1.  Aileron trim is electrically actuated , 1 tab on left aileron

2.  Elevator trim is manual servo cable system, 1 tab on left elevator

3.  Rudder trim is manual servo cable system, tab on upper elevator

C. Secondary Controls

1.  Flaps

    a.  Mechanically activated, hydraulically actuated

    b.  Consist of inner and outer foreflaps, and inner trailing flaps

    c.  Flap selector is on overhead console

    d.  Flap indicator on center window post

    e.  May select any setting between 0 and 37.5 degrees

    f.  Flap-Elevator interconnect tab

> 1\. Located on right elevator
>
> 2\. Counteracts the pitch up that accompanies flap selection

# Ice and Rain Protection

A. Powerplant Ice and Rain Protection

1.  Intake deflectors

    a.  Prevent moisture particles from entering inlet plenum

    b.  Heavier particles unable to make turn are discharged

    c.  Must be used in visible moisture below plus 5 degrees C

    d.  Operated by switch on overhead panel; actuated by bleed air

    e.  Slight decrease in torque when deflectors actuated, also a
        slight

> Increase in ITT

f.  Three position switch spring loaded to center

g.  Switch is held 3 to 5 seconds to extend deflectors, but requires

> Only momentary movement to retract

2.  Propeller

    a.  Each propeller blade has two electrically heated elements-

> An inner and an outer

b.  Powered from left DC bus though a 20A circuit breaker

c.  When switched on the automatic timer sequences: 30 seconds left
    outer,

> 30 seconds left inner, 30 seconds right outer, 30 seconds right inner,
>
> repeat. ( total cycle two minutes)

d.  Heat should be selected before icing occurs

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3.  Oil to Fuel Heater

    a.  Fuel is heated by oil/fuel heat exchanger

    b.  Operates continuously with engines running

B. Airframe Ice and Rain Protection

1\. Windshield wipers

a.  Powered by one 28 VDC electric motor

b.  Switch positions OFF, SLOW, PARK, and FAST

c.  Do not operate on dry windshield

d.  Use PARK to bring wiper arms to their most inboard position

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2.  Windshield Heat

    a.  Each side is powered from associated DC bus through 30A circuit

> Breakers located in the power distribution and control box (not
>
> Accessible in flight)

b.  Controlled by switch labeled WINDSHIELD HEAT

c.  Maximum ground operation limited to 10 minutes

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3.  Pitot and Stall Vane Heat

    a.  One switch (PITOT HEAT) operates stall vane heat and both pitot
        heats

    b.  Do not operate on ground except for short periods

**Ice and Rain Protection (continued)**

4\. Surface Deice System

a\. Inflatable rubber boots on wings and horizontal stabilizer

b\. Boots operated by engine bleed air

c\. Wing inspection lights on each nacelle

d\. Ejector flow control valves

1\. Normally de-energized, creating suction in boots

2\. 1 in each wing, 1 in aft fuselage

3\. Each has electric heater controlled by switch on overhead panel

e\. Automatic operation

1\. Select bleed air switches on

2\. Select valve heater switch on

3\. Select MANUAL/OFF/AUTO switch to AUTO

4\. SLOW/FAST switch

a\. Select FAST, and ejector valves will energize in sequence to inflate

inner boots for 5 seconds, outer boots for 5 seconds, left stabilizer

for 3 seconds, right stab for 3 seconds, dwell for 44 seconds, repeat

b\. Select SLOW, and ejector valves will energize in sequence to inflate

inner boots for 5 seconds, outer boots for 5 seconds, left stabilizer

for 3 seconds, right stab for 3 seconds, dwell for 164 seconds, repeat

5\. Visually verify wing boot operation, and blue lights on overhead
panel

will verify tail ejector valve has been energized

f\. Manual operation

1\. Select bleed air switches on

2\. Select valve heater switch on

3\. Select MANUAL/OFF/AUTO switch to MANUAL

4\. Select INNER WING or OUTER WING or LEFT STAB or RIGHT STAB,

boot will stay inflated as long as you hold the spring loaded switch on

5\. Visually verify wing boot operation, and blue lights on overhead
panel

will verify that the tail ejector valve has been energized.

Note: Airworthiness Directive 2000-06-03 BOMBARDIER INC.; Amendment
39-11643; Docket No. 99-CE-44-AD went into effect on May 5. 2000. Here
is what it says:

For DHC-6 Aircraft, with wing and tail leading edge pneumatic deicing
boot system installed, *[must activate the deicing system at the first
sign of ice formation anywhere on the]{.underline}
[aircraft.]{.underline}* The system must be continued to be operated in
the automatic cycling mode, if available. The system may be deactivated
only after leaving known or observed icing that the flight crew has
visually observed on the aircraft and the airplane is determined to be
clear of ice. Compliance with the above is required except for phases of
flight that the AFM specifies that deicing boots should not be used
(e.g., take-off, final approach, and landing).

**Oxygen System**

The crew oxygen system is a diluter-demand system, providing oxygen for
the pilot and copilot through demand regulators.

A. Components

1.  Oxygen cylinder

    a.  Green 650 cubic inch capacity

    b.  Located forward of the station 60 bulkhead, below the avionic
        equipment shelves.

    c.  Accessed from nose baggage compartment.

    d.  Full charge is 1800+/-50 psi

2.  Pressure gauge and charging valve.

    a.  Direct-reading gauge

    b.  Calibrated from 0 to 2000 psi in 200 psi increments

    c.  Charging valve is adjacent to the pressure gauge and is accessed
        from the nose baggage compartment.

3.  Regulators

    a.  One each for pilot and copilot

    b.  Located on lower subpanel of each instrument panel

4.  Masks

    a.  Located on bulkhead behind crew seats.

    b.  Equipped with quick disconnect fittings.

# Ventilation and Heating System

A. Ventilation

1.  Cabin gasper outlets

    a.  Controlled by passengers

    b.  Fresh air from Ram-air inlet only

    c.  Ram-air always available

    d.  For added ventilation during ground operations, turn on the
        Ram-air Fan.

2.  Cabin baseboard outlets

    a.  Controlled by pilot via the Ram-air Valve on center pedestal,
        and the Cabin Air Control Knob on the floor behind copilot's
        chair

    b.  When the Ram-air valve and the Cabin Air Control Knob are both
        open, low velocity air emerges from the cabin baseboard outlets.

3.  Flight compartment outlets

    a.  Controlled by the pilot via the Ram-air valve

    b.  For maximum ventilation during warm weather operations, select
        the Ram-air valve open, and close the Cabin air Control. This
        configuration provides large quantities of high velocity air to
        the flight compartment. (Passengers may obtain their own supply
        of high velocity air by opening the individual gasper outlets.)

**Ventilation and Heating System (continued)**

4.  Flight compartment Fans

    a.  One each for pilot and copilot

    b.  Individually controlled with switch on back of fan

5.  Air exhaust

    a.  Through grills in the cabin ceiling and exits the fuselage
        through an aft facing scoop on top of the aircraft.

    b.  Through screen located at back of rear cargo compartment and
        exits through plastic guards covering rudder bellcrank

6.  Emergency air evacuation

    a.  In an emergency, open the flight compartment windows

        1.  most effective

        2.  Note: any smoke and fumes in the cabin will be drawn through
            the flight compartment

    b.  Without opening the windows, try this:

        1.  Ram-air fully open

        2.  Cabin Air Valve fully closed

        3.  Heat Off

        4.  Bleed Air Switches off (if there is any reason to suspect
            the quality of the air being delivered from the engine bleed
            air system)

B. Heating System

The cabin and flight compartment may be heated by injecting hot bleed
air from the engines into the ventilation system. This bleed air is
mixed with either cool air from the ram-air inlet or air recirculated
from inside the aircraft, and is available through the cabin baseboard
outlets or the flight compartment outlets as selected by the pilot. The
passenger gasper outlets always deliver only air from the ram-air inlet
if the gasper is opened.

1.  Manual Mode

    a.  Select BLEED AIR switches to ON

    b.  Select MANUAL on the 3 position mode switch located in the TEMP
        CONTROL area of the overhead panel.

    c.  Toggle the switch labeled MANUAL COOL/ MANUAL WARM to modulate
        the amount of hot bleed air that enters the system

2.  Automatic Mode

    a.  Select BLEED AIR switches to ON

    b.  Select AUTO on the 3 position mode switch

    c.  Turn the TEMP CONTROL knob to achieve the desired temperature. A
        cabin temperature Sensor in the forward cabin bulkhead will
        maintain a constant cabin temperature.

In either mode, the Ram-air valve should be slightly open to provide a
motive force to move the hot air out of the plenum and into the cabin.
This will result in faster cabin warmup.