Federal Register / Vol. 79, No. 162 / Thursday, August 21, 2014 / Rules and Regulations 49427 

the anonymous comment is beyond the 

scope of this special condition, and is 

already accounted for and considered in 

the basic regulatory-compliance process. 

Applicability 

As discussed above, these special 

conditions apply to Airbus Model 

A350–900 airplanes. Should Airbus 

apply later for a change to the type 

certificate to include another model 

incorporating the same novel or unusual 

design feature, the special conditions 

would apply to that model as well. 

Conclusion 

This action affects only certain novel 

or unusual design features on Airbus 

Model A350–900 series airplanes. It is 

not a rule of general applicability. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

The authority citation for these 

special conditions is as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701, 

44702, 44704. 

The Special Conditions 

■ Accordingly, pursuant to the authority 

delegated to me by the Administrator, 

the following special conditions are 

issued as part of the type-certification 

basis for Airbus Model A350–900 series 

airplanes. 

In addition to § 25.143, the following 

requirements apply: Operation of the 

high-speed limiter during all routine 

and descent-procedure flight must not 

impede normal attainment of speeds up 

to overspeed warning. 

Issued in Renton, Washington, on August 

15, 2014. 

Jeffrey E. Duven, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2014–19822 Filed 8–20–14; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–1001; Special 

Conditions No. 25–535–SC] 

Special Conditions: Airbus Model 

A350–900 Airplanes; High-Speed 

Protection System 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for Airbus Model A350–900 

airplanes. These airplanes will have a 

novel or unusual design feature 

associated with a high-speed protection 

system that limits nose-down pilot 

authority at speeds above VC/MC, and 

prevents the airplane from performing 

the maneuver required under the Code 

of Federal Regulations. The applicable 

airworthiness regulations do not contain 

adequate or appropriate safety standards 

for this design feature. These special 

conditions contain the additional safety 

standards that the Administrator 

considers necessary to establish a level 

of safety equivalent to that established 

by the existing airworthiness standards. 

DATES: Effective date: September 22, 

2014. 

FOR FURTHER INFORMATION CONTACT: 

Todd Martin, FAA, Airframe/Cabin 

Safety, ANM–115, Transport Airplane 

Directorate, Aircraft Certification 

Service, 1601 Lind Avenue SW., 

Renton, Washington 98057–3356; 

telephone (425) 227–1178; facsimile 

(425) 227–1322. 

SUPPLEMENTARY INFORMATION: 

Background 

On August 25, 2008, Airbus applied 

for a type certificate for their new Model 

A350–900 airplane. Later, Airbus 

requested, and the FAA approved, an 

extension to the application for FAA 

type certification to November 15, 2009. 

The Model A350–900 airplane has a 

conventional layout with twin wingmounted Rolls-Royce Trent XWB 

engines. It features a twin-aisle, 9- 

abreast, economy-class layout, and 

accommodates side-by-side placement 

of LD–3 containers in the cargo 

compartment. The basic Model A350– 

900 airplane configuration 

accommodates 315 passengers in a 

standard two-class arrangement. The 

design cruise speed is Mach 0.85 with 

a maximum take-off weight of 602,000 

lbs. 

The Model A350–900 airplane, like 

Airbus Model A320, A330, A340 and 

A380 series airplanes, has a high-speed 

protection system that limits nose-down 

pilot authority at speeds above VC/MC, 

and prevents the airplane from actually 

performing the maneuver required 

under § 25.335(b)(1). Special conditions 

are necessary to address the Model 

A350–900 airplane high-speed 

protection system. These special 

conditions identify various symmetric 

and non-symmetric maneuvers that will 

ensure that an appropriate design dive 

speed, VD/MD, is established. 

Type Certification Basis 

Under Title 14, Code of Federal 

Regulations (14 CFR) 21.17, Airbus must 

show that the Model A350–900 airplane 

meets the applicable provisions of part 

25, as amended by Amendments 25–1 

through 25–129. 

If the Administrator finds that the 

applicable airworthiness regulations 

(i.e., 14 CFR part 25) do not contain 

adequate or appropriate safety standards 

for the Model A350–900 airplane 

because of a novel or unusual design 

feature, special conditions are 

prescribed under the provisions of 

§ 21.16. 

Special conditions are initially 

applicable to the model for which they 

are issued. Should the type certificate 

for that model be amended later to 

include any other model that 

incorporates the same or similar novel 

or unusual design feature, the special 

conditions would also apply to the other 

model under § 21.101. 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Model A350–900 

airplane must comply with the fuel-vent 

and exhaust-emission requirements of 

14 CFR part 34, and the noisecertification requirements of 14 CFR 

part 36. The FAA must issue a finding 

of regulatory adequacy under section 

611 of Public Law 92–574, the ‘‘Noise 

Control Act of 1972.’’ 

The FAA issues special conditions, as 

defined in 14 CFR 11.19, under § 11.38, 

and they become part of the typecertification basis under § 21.17(a)(2). 

Novel or Unusual Design Features 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Model A350–900 

airplane must comply with the fuel-vent 

and exhaust-emission requirements of 

14 CFR part 34, and the noisecertification requirements of 14 CFR 

part 36. The FAA must issue a finding 

of regulatory adequacy under § 611 of 

Public Law 92–574, the ‘‘Noise Control 

Act of 1972.’’ 

The Airbus Model A350–900 airplane 

will incorporate the following novel or 

unusual design features: 

A high-speed protection system that 

limits nose-down pilot authority at 

speeds above VC/MC, and prevents the 

airplane from actually performing the 

maneuver required under § 25.335(b)(1). 

The special conditions identify various 

symmetric and non-symmetric 

maneuvers that will ensure that an 

appropriate design dive speed, VD/MD, 

is established. 

Discussion 

Section 25.335(b)(1) is an analytical 

envelope condition originally adopted 

in Part 4b of the Civil Air Regulations 

to provide an acceptable speed margin 


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49428 Federal Register / Vol. 79, No. 162 / Thursday, August 21, 2014 / Rules and Regulations 

between design cruise speed and design 

dive speed. Flutter-clearance design 

speeds and airframe design loads are 

impacted by the design dive speed. 

While the initial condition for the upset 

specified in the rule is 1g level flight, 

protection is afforded for other 

inadvertent overspeed conditions as 

well. Section 25.335(b)(1) is intended as 

a conservative enveloping condition for 

potential overspeed conditions, 

including non-symmetric conditions. 

To establish that potential overspeed 

conditions are enveloped, Airbus 

should demonstrate that any reduced 

speed margin, based on the high-speed 

protection system in the Model A350– 

900 airplane, will not be exceeded in 

inadvertent, or gust-induced, upsets 

resulting in initiation of the dive from 

non-symmetric attitudes; or that the 

airplane is protected, by the flightcontrol laws, from getting into nonsymmetric upset conditions. The special 

conditions identify various symmetric 

and non-symmetric maneuvers that will 

ensure that an appropriate design dive 

speed, VD/MD, is established. 

These special conditions are in lieu of 

§ 25.335(b)(1). Section 25.335(b)(2), 

which also addresses the design dive 

speed, is applied separately (Advisory 

Circular (AC) 25.335–1A provides an 

acceptable means of compliance to 

§ 25.335(b)(2)). The applicant should 

conduct a demonstration that includes a 

comprehensive set of conditions, as 

described below. 

Special conditions (3) and (4) indicate 

that failures of the high-speed 

protection system must be improbable 

and must be annunciated to the pilots. 

If these two criteria are not met, then the 

probability that the established dive 

speed will be exceeded, and the 

resulting risk to the airplane, is too 

great. On the other hand, if the highspeed protection system is known to be 

inoperative, then dispatch of the 

airplane could be acceptable under an 

approved minimum-equipment list 

(MEL) containing language similar to 

special condition (5). Dispatch under an 

MEL would require that appropriate 

reduced operating speeds, VMO/MMO, 

are provided in the airplane flight 

manual (AFM), and the cockpit display 

of those reduced speeds, as well as the 

overspeed warning for exceeding those 

speeds, are equivalent to that of the 

normal airplane with the high-speed 

protection system operative. 

We do not believe that application of 

the Interaction of Systems and 

Structures special conditions (docket 

no. FAA–2013–0894), or the European 

Aviation Safety Agency (EASA) 

Certification Specification (CS) 25.302, 

is appropriate in this case because 

design dive speed is, in and of itself, 

part of the design criteria. Stability and 

control, flight loads, and flutter 

evaluations all depend on the design 

dive speed. Therefore, a single design 

dive speed should be established that 

will not be exceeded, taking into 

account the performance of the highspeed protection system as well as its 

failure modes, failure indications, and 

accompanying AFM instructions. 

These special conditions contain the 

additional safety standards that the 

Administrator considers necessary to 

establish a level of safety equivalent to 

that established by the existing 

airworthiness standards. 

Discussion of Comments 

Notice of proposed special conditions 

No. 25–13–35–SC for Airbus Model 

A350–900 airplanes was published in 

the Federal Register on December 24, 

2013 (78 FR 77611). No comments were 

received and the special conditions are 

adopted as proposed. 

Applicability 

As discussed above, these special 

conditions apply to Airbus Model 

A350–900 airplanes. Should Airbus 

apply at a later date for a change to the 

type certificate to include another 

airplane series incorporating the same 

novel or unusual design feature, the 

special conditions would apply to that 

series as well. 

Conclusion 

This action affects only certain novel 

or unusual design features on the Airbus 

Model A350–900 series airplanes. It is 

not a rule of general applicability. 

List of Subjects in 14 CFR Part 25 

Aircraft, Aviation safety, Reporting 

and recordkeeping requirements. 

The authority citation for these 

special conditions is as follows: 

Authority: 49 U.S.C. 106(g), 40113, 44701, 

44702 and 44704. 

The Special Conditions 

Accordingly, pursuant to the 

authority delegated to me by the 

Administrator, the following special 

conditions are issued as part of the typecertification basis for Airbus Model 

A350–900 series airplanes. 

1. In lieu of compliance with 

§ 25.335(b)(1), if the flight-control 

system includes functions that act 

automatically to initiate recovery before 

the end of the 20-second period 

specified in § 25.335(b)(1), VD/MD must 

be determined from the greater of the 

speeds resulting from conditions (a) and 

(b), below. The speed increase occurring 

in these maneuvers may be calculated if 

reliable or conservative aerodynamic 

data are used. 

a. From an initial condition of 

stabilized flight at VC/MC, the airplane 

is upset so as to travel a new flight path 

7.5 degrees below the initial path. 

Control application, up to full authority, 

is made to try to maintain this new 

flight path. Twenty seconds after 

initiating the upset, manual recovery is 

made at a load factor of 1.5 g (0.5 

acceleration increment), or such greater 

load factor that is automatically applied 

by the system with the pilot’s pitch 

control set to neutral. Power, as 

specified in § 25.175(b)(1)(iv), is 

assumed until recovery is initiated, at 

which time power reduction and the use 

of pilot-controlled drag devices may be 

used. 

b. From a speed below VC/MC, with 

power to maintain stabilized level flight 

at this speed, the airplane is upset so as 

to accelerate through VC/MC at a flight 

path 15 degrees below the initial path 

(or at the steepest nose-down attitude 

that the system will permit with full 

control authority, if less than 15 

degrees). The pilot’s controls may be in 

the neutral position after reaching VC/

MC and before recovery is initiated. 

Recovery may be initiated three seconds 

after operation of the high-speed 

warning system by application of a load 

of 1.5g (0.5 acceleration increment), or 

such greater load factor that is 

automatically applied by the system 

with the pilot’s pitch control set to 

neutral. Power may be reduced 

simultaneously. All other means of 

decelerating the airplane, the use of 

which is authorized up to the highest 

speed reached in the maneuver, may be 

used. The interval between successive 

pilot actions must not be less than one 

second. 

2. The applicant must also 

demonstrate that the speed margin, 

established as above, will not be 

exceeded in inadvertent, or gustinduced, upsets resulting in initiation of 

the dive from non-symmetric attitudes, 

unless the airplane is protected by the 

flight-control laws from getting into 

non-symmetric upset conditions. The 

upset maneuvers described in AC 25– 

7C, Chapter 2, Section 8, Paragraph 

32c.(3)(a) and (c), may be used to 

comply with this requirement. 

3. Detected loss of the high-speed 

protection function must be less than 

10¥3 per flight hour. 

4. Failures of the system must be 

annunciated to the pilots. The 

Operating Limitations Section of the 

AFM must contain instructions that 

reduce the maximum operating speeds, 

Vmax/Mmax, to a value that maintains a 

speed margin between these speeds and 


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Federal Register / Vol. 79, No. 162 / Thursday, August 21, 2014 / Rules and Regulations 49429 

VD/MD that is consistent with showing 

compliance to § 25.335(b), without the 

benefit of the high-speed protection 

system. 

5. Dispatch of the airplane with the 

high-speed protection system 

inoperative is prohibited except under 

an approved MEL that requires AFM 

instructions to indicate reduced 

maximum operating speeds, as 

described in special condition (4), 

above. In addition, the cockpit display 

of the reduced operating speeds, as well 

as the overspeed warning for exceeding 

those speeds, must be equivalent to that 

of the normal airplane with the highspeed protection system operative. Also, 

it must be shown that no additional 

hazards are introduced with the highspeed protection system inoperative. 

Issued in Renton, Washington, on July 30, 

2014. 

Jeffrey E. Duven, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2014–19824 Filed 8–20–14; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 25 

[Docket No. FAA–2013–0908; Special 

Conditions No. 25–538–SC] 

Special Conditions: Airbus Model 

A350–900 Series Airplane; Airplane 

Level of Safety Provided by Composite 

Fuel-Tank Structure: Post-Crash Fire 

Survivability 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final special conditions. 

SUMMARY: These special conditions are 

issued for Airbus Model A350–900 

series airplanes. These airplanes will 

have a novel or unusual design feature 

associated with the post-crash fire 

survivability of composite fuel tanks. 

The applicable airworthiness 

regulations do not contain adequate or 

appropriate safety standards for this 

design feature. These special conditions 

contain the additional safety standards 

that the Administrator considers 

necessary to establish a level of safety 

equivalent to that established by the 

existing airworthiness standards. 

DATES: Effective date: September 22, 

2014. 

FOR FURTHER INFORMATION CONTACT: 

Doug Bryant, Propulsion and 

Mechanical Systems, ANM–112, 

Transport Airplane Directorate, Aircraft 

Certification Service, 1601 Lind Avenue 

SW., Renton, Washington 98057–3356; 

telephone (425) 227–2384; facsimile 

(425) 227–1320. 

SUPPLEMENTARY INFORMATION: 

Background 

On August 25, 2008, Airbus applied 

for a type certificate for their new Model 

A350–900 series airplane. Later, Airbus 

requested, and the FAA approved, an 

extension to the application for FAA 

type certification to November 15, 2009. 

The Model A350–900 series airplane 

has a conventional layout with twin 

wing-mounted Rolls-Royce Trent XWB 

engines. It features a twin-aisle, 9- 

abreast, economy-class layout, and 

accommodates side-by-side placement 

of LD–3 containers in the cargo 

compartment. The basic Model A350– 

900 series airplane configuration 

accommodates 315 passengers in a 

standard two-class arrangement. The 

design cruise speed is Mach 0.85 with 

a maximum take-off weight of 602,000 

lbs. 

The Model A350–900 series airplane 

will be the second large, transportcategory airplane certificated with 

composite wing and fuel-tank structure 

that may be exposed to the direct effects 

of post-crash ground, or under-wing, 

fuel-fed fires. Although the FAA has 

previously approved fuel tanks made of 

composite materials located in the 

horizontal stabilizer of some airplanes, 

the composite wing structure of the 

Model A350–900 series airplane will 

incorporate a new fuel-tank 

construction into service. 

Advisory Circular (AC) 20–107A, 

Composite Aircraft Structure, under the 

topic of flammability, states: 

The existing requirements for 

flammability and fire protection of 

aircraft structure attempt to minimize 

the hazard to the occupants in the event 

ignition of flammable fluids or vapors 

occurs. The use of composite structure 

should not decrease this existing level 

of safety. 

Pertinent to the wing structure, postcrash-fire passenger survivability is 

dependent on the time available for 

passenger evacuation prior to fuel-tank 

breach or structural failure. Structural 

failure can be a result of degradation in 

load-carrying capability in the upper or 

lower wing surface caused by a fuel-fed 

ground fire. Structural failure can also 

be a result of over-pressurization caused 

by ignition of fuel vapors inside the fuel 

tank. 

The inherent capability of aluminum 

to resist fire has been considered by the 

FAA in development of the current 

regulations. Title 14, Code of Federal 

Regulations (14 CFR) part 25 Chapter 1, 

Section 1.1, General Definitions, defines 

‘‘fire resistant’’ to mean, with respect to 

sheet or structural members, the 

capacity to withstand heat associated 

with fire at least as well as aluminum 

alloy does in dimensions appropriate for 

the purpose for which those materials 

are used. 

Note that aluminum alloy is identified 

as the performance standard for fire 

resistance, although no thickness or heat 

intensities are defined. Based on the 

performance of aluminum alloy, the 

definition of ‘‘fire resistance’’ was later 

defined, for testing of other materials in 

AC 20–135, as the capability to 

withstand a 2000 °F flame for five 

minutes. 

The FAA has historically issued rules 

with the assumption that the material of 

construction for wing and fuselage 

would be aluminum. As a representative 

case, 14 CFR 25.963 was issued as a 

result of a large, fuel-fed fire following 

the failures of fuel-tank access doors 

caused by uncontained engine failures. 

During the subsequent Aviation 

Rulemaking Advisory Committee 

(ARAC) harmonization process, the 

structures group attempted to 

harmonize § 25.963 regarding the 

impact-and-fire resistance of the fueltank access panels. Discussions between 

the FAA and the European Aviation 

Safety Agency (EASA), formerly the 

European Joint Aviation Authorities 

(JAA), ensued regarding the need for fire 

resistance of the fuel-tank access panels. 

The EASA position was that the FAA 

requirement for the access panels to be 

fire resistant, when the surrounding 

wing structure was not required to be 

fire resistant, was inconsistent, and that 

the access panels only needed to be as 

fire resistant as the surrounding tank 

structure. The FAA position stated that 

the fuel-tank access-panel fire-resistance 

requirement should be retained, and 

that, long-term, a minimum requirement 

should be created for the wing skin 

itself. Both authorities recognized that 

existing aluminum wing structure 

provided an acceptable level of safety. 

Further rulemaking has not yet been 

pursued. 

As with previous Airbus airplane 

designs with under-wing-mounted 

engines, the wing tanks and center tanks 

are located in proximity to the 

passengers and near the engines. Past 

experience indicates that post-crash 

survivability is greatly influenced by the 

size and intensity of any fire that occurs. 

The ability of aluminum wing surfaces, 

wetted by fuel on their interior surface, 

to withstand post-crash fire conditions, 

has been demonstrated by tests 

conducted at the FAA William J. 


tkelley on DSK3SPTVN1PROD with RULES