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
49430 Federal Register / Vol. 79, No. 162 / Thursday, August 21, 2014 / Rules and Regulations 

1Hill, R., and Johnson, G.R., ‘‘Investigation of 

Aircraft Fuel Tank Explosions and Nitrogen Inerting 

Requirements During Ground Fires,’’ FAA Report 

DOT/FAA/RD–75–119, October 1975. Available via 

the FAA Technical Center Web site for Fire Safety 

at http://www.fire.tc.faa.gov/. 

2Cherry, R. and Warren, K. ‘‘Fuselage 

Burnthrough Protection for Increased Postcrash 

Occupant Survivability: Safety Benefit Analysis 

Based on Past Accidents, ‘‘FAA Report DOT/FAA/ 

AR–99/57, September 1999 and R G W Cherry & 

Associates Limited, ‘‘A Benefit Analysis for Cabin 

Water Spray Systems and Enhanced Fuselage 

Burnthrough Protection,’’ FAA Report DOT/FAA/ 

AR–02/49, April 7, 2003. 

Hughes Technical Center.1 Results of 

these tests have verified adequate 

dissipation of heat across wetted 

aluminum fuel-tank surfaces so that 

localized hot spots do not occur, thus 

minimizing the threat of explosion. This 

inherent capability of aluminum to 

dissipate heat also allows the wing 

lower surface to retain its load-carrying 

characteristics during a fuel-fed ground 

fire, and significantly delay wing 

collapse or burn-through for a time 

interval that usually exceeds evacuation 

times. In addition, as an aluminum fuel 

tank is heated with significant 

quantities of fuel inside, fuel vapor 

accumulates in the ullage space, 

exceeding the upper flammability limit 

relatively quickly and thus reducing the 

threat of a fuel-tank explosion prior to 

fuel-tank burn-through. Service history 

of conventional aluminum airplanes has 

shown that fuel-tank explosions caused 

by ground fires have been rare on 

airplanes configured with flame 

arrestors in the fuel-tank vent lines. Fuel 

tanks constructed with composite 

materials may or may not have 

equivalent capability. 

Due to the inherent properties 

provided by aluminum skin and 

structure, current regulations may not 

be adequate as they were developed, 

and have evolved under the assumption 

that wing construction would be of 

aluminum materials. Inherent properties 

of aluminum, with respect to fuel tanks 

and fuel-fed fires, are as follows: 

• Aluminum is highly thermally 

conductive and readily transmits the 

heat of a fuel-fed external fire to fuel in 

the tank. This has the benefit of rapidly 

driving the fuel-tank ullage to exceed 

the upper flammability limit prior to 

burn-through of the fuel-tank skin, or 

heating of the wing upper surface above 

the auto-ignition temperature, thus 

greatly reducing the threat of fuel-tank 

explosion. 

• Aluminum panels at thicknesses 

previously used in wing lower surfaces 

of large, transport-category airplanes 

have been fire resistant as defined in 14 

CFR 1.1 and AC 20–135. 

• Heat capacity of aluminum and fuel 

prevents burn-through or wing collapse 

for a time interval that generally exceeds 

the passenger evacuation time. 

Type Certification Basis 

Under 14 CFR 21.17, Airbus must 

show that the Model A350–900 series 

airplane meets the applicable provisions 

of 14 CFR 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 series airplane 

because of a novel or unusual design 

feature, special conditions are 

prescribed under § 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. 

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). 

In addition to the applicable 

airworthiness regulations and special 

conditions, the Model A350–900 series 

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.’’ 

Novel or Unusual Design Features 

The Airbus Model A350–900 series 

airplane will incorporate the following 

novel or unusual design feature: 

Composite fuel tanks. 

Discussion 

The extensive use of composite 

materials in the design of the A350–900 

airplane wing and fuel-tank structure is 

considered a major change from 

conventional and traditional methods of 

construction, as this will be only the 

second large, transport-category airplane 

design to be certificated with this level 

of composite material for these 

purposes. The applicable airworthiness 

regulations do not contain specific 

standards for post-crash fire-safety 

performance of wing and fuel-tank skin 

or structure. 

To provide the same level of safety as 

exists with conventional airplane 

construction, Airbus must demonstrate 

that the Model A350–900 series airplane 

has sufficient post-crash survivability to 

enable occupants to safely evacuate in 

the event that the wings are exposed to 

a large, fuel-fed fire. Factors in fuel-tank 

survivability are the structural integrity 

of the wing and tank; flammability of 

the tank; burn-through resistance of the 

wing skin; and the presence of autoignition threats during exposure to a 

fire. The FAA assessed post-crash 

survival time during the adoption of 

Amendment 25–111 for fuselage burnthrough protection. Studies conducted 

by, and on behalf of, the FAA indicated 

that, following a survivable accident, 

prevention of fuselage burn-through for 

approximately 5 minutes can 

significantly enhance survivability.2

There is little benefit in requiring the 

design to prevent wing-skin burnthrough beyond five minutes, due to the 

effects of the fuel fire itself on the rest 

of the airplane. That assessment was 

carried out based on accidents involving 

airplanes with conventional fuel tanks, 

and considering the ability of ground 

personnel to rescue occupants. In 

addition, AC 20–135 indicates that, 

when aluminum is used for fuel tanks, 

the tank should withstand the effects of 

fire for 5 minutes without failure. 

Therefore, to be consistent with existing 

capability and related requirements, the 

Model A350–900 series airplane fuel 

tanks must be capable of resisting a 

post-crash fire for at least 5 minutes. In 

demonstrating compliance, Airbus must 

address a range of fuel loads from 

minimum to maximum, as well as any 

other critical fuel load. 

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. 25–13–24–SC for Airbus 

Model A350–900 series airplanes was 

published in the Federal Register on 

January 8, 2014 (79 FR 1334). 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 series 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 under the provisions of § 21.101. 


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Federal Register / Vol. 79, No. 162 / Thursday, August 21, 2014 / Rules and Regulations 49431 

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 type-certification 

basis for Airbus Model A350–900 series 

airplanes. 

In addition to complying with 14 CFR 

part 25 regulations governing the firesafety performance of the fuel tanks, 

wings, and nacelle, the Airbus Model 

A350–900 series airplane must 

demonstrate acceptable post-crash 

survivability in the event the wings are 

exposed to a large fuel-fed ground fire. 

Airbus must demonstrate that the wing 

and fuel-tank design can endure an 

external fuel-fed pool fire for at least 

five minutes. This must be 

demonstrated for minimum fuel loads 

(not less than reserve fuel levels) and 

maximum fuel loads (maximum-range 

fuel quantities), and other identified 

critical fuel loads. Considerations must 

include fuel-tank flammability, burnthrough resistance, wing structuralstrength retention properties, and autoignition threats during a ground-fire 

event for the required time duration. 

Issued in Renton, Washington, on August 

1, 2014. 

Jeffrey E. Duven, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2014–19823 Filed 8–20–14; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2014–0124; Directorate 

Identifier 2012–NM–197–AD; Amendment 

39–17944; AD 2014–16–20] 

RIN 2120–AA64 

Airworthiness Directives; Airbus 

Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: We are adopting a new 

airworthiness directive (AD) for all 

Airbus Model A300 series airplanes. 

This AD was prompted by an analysis 

of the impacts of extended service goal 

activities on Airbus Model A300 series 

airplanes. This AD requires revising the 

maintenance or inspection program. We 

are issuing this AD to prevent failure of 

flight critical systems. 

DATES: This AD becomes effective 

September 25, 2014. 

ADDRESSES: You may examine the AD 

docket on the Internet at http:// 

www.regulations.gov/ 

#!docketDetail;D=FAA-2014-0124; or in 

person at the Docket Management 

Facility, U.S. Department of 

Transportation, Docket Operations, M– 

30, West Building Ground Floor, Room 

W12–140, 1200 New Jersey Avenue SE., 

Washington, DC. 

FOR FURTHER INFORMATION CONTACT: Dan 

Rodina, Aerospace Engineer, 

International Branch, ANM–116, 

Transport Airplane Directorate, FAA, 

1601 Lind Avenue SW., Renton, WA 

98057–3356; telephone 425–227–2125; 

fax 425–227–1149. 

SUPPLEMENTARY INFORMATION: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 by adding an AD that would 

apply to all Airbus Model A300 series 

airplanes. The NPRM published in the 

Federal Register on February 28, 2014 

(79 FR 11358). The NPRM was 

prompted by an analysis of the impacts 

of extended service goal activities on 

Airbus Model A300 series airplanes. 

The NPRM proposed to require revising 

the maintenance program. We are 

issuing this AD to prevent failure of 

flight critical systems. 

The European Aviation Safety Agency 

(EASA), which is the Technical Agent 

for the Member States of the European 

Community, has issued EASA 

Airworthiness Directive 2012–0233, 

dated November 7, 2012 (referred to 

after this as the Mandatory Continuing 

Airworthiness Information, or ‘‘the 

MCAI’’), to correct an unsafe condition 

on all Airbus Model A300 series 

airplanes. The MCAI states: 

The results of the Extended Service Goal 

(ESG) exercise for A300 series aeroplanes 

(75,000 flight hours (FH) or 48,000 flight 

cycles (FC), whichever occurs first) identified 

certain operational tests as Airworthiness 

Limitation Items (ALI), necessary to ensure 

the safety objectives for aeroplanes which 

have accumulated or exceeded 60,000 FH. 

These ALI are not fully new, since all nine 

tasks derive from existing Maintenance 

Planning Document (MPD) tasks. 

Consequently, the intervals of those nine 

tasks can no longer be escalated or retained 

at an interval higher than that specified in 

this [EASA] AD for each task. 

Failure to comply with these tasks within 

the established maximum intervals could be 

detrimental to the safety of the affected 

aeroplanes. 

For the reasons described above, this 

[EASA] AD requires the implementation of 

nine specific operational ALI test for 

aeroplanes which have accumulated or 

exceeded 60,000 FH. 

In addition, Airbus performed an analysis 

of the impacts of ESG activities on A300 

series aeroplanes and, based on the results, 

this [EASA] AD publishes an operational life 

of 75,000 FH or 48,000 FC, whichever occurs 

first, applicable to A300 system installations. 

You may examine the MCAI in the 

AD docket on the Internet at http:// 

www.regulations.gov/ 

#!documentDetail;D=FAA-2014-0124- 

0002. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

received no comments on the NPRM (79 

FR 11358, February 28, 2014) or on the 

determination of the cost to the public. 

‘‘Contacting the Manufacturer’’ 

Paragraph in This AD 

Since late 2006, we have included a 

standard paragraph titled ‘‘Airworthy 

Product’’ in all MCAI ADs in which the 

FAA develops an AD based on a foreign 

authority’s AD. 

The MCAI or referenced service 

information in an FAA AD often directs 

the owner/operator to contact the 

manufacturer for corrective actions, 

such as a repair. Briefly, the Airworthy 

Product paragraph allowed owners/ 

operators to use corrective actions 

provided by the manufacturer if those 

actions were FAA-approved. In 

addition, the paragraph stated that any 

actions approved by the State of Design 

Authority (or its delegated agent) are 

considered to be FAA-approved. 

In the NPRM (79 FR 11358, February 

28, 2014), we proposed to prevent the 

use of repairs that were not specifically 

developed to correct the unsafe 

condition, by requiring that the repair 

approval provided by the State of 

Design Authority or its delegated agent 

specifically refer to this FAA AD. This 

change was intended to clarify the 

method of compliance and to provide 

operators with better visibility of repairs 

that are specifically developed and 

approved to correct the unsafe 

condition. In addition, we proposed to 

change the phrase ‘‘its delegated agent’’ 

to include a design approval holder 

(DAH) with State of Design Authority 

design organization approval (DOA), as 

applicable, to refer to a DAH authorized 

to approve required repairs for the 

proposed AD. 


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