
[Federal Register Volume 79, Number 113 (Thursday, June 12, 2014)]
[Rules and Regulations]
[Pages 33674-33675]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-13667]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0890; Special Conditions No. 25-524-SC]


Special Conditions: Airbus Model A350-900 Series Airplane; Ground 
Pivoting Loads

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for Airbus Model A350-900 
Series airplanes. These airplanes will have a novel or unusual design 
feature(s) associated with a braking system that affects the airplane's 
pivoting behavior. 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 July 14, 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) 227-1320.

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 
June 28, 2009. The Model A350-900 series airplane has a conventional 
layout with twin wing-mounted Rolls-Royce Trent 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 configuration will accommodate 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. Airbus proposes the 
Model A350-900 series airplane to be certified for extended operations 
(ETOPS) beyond 180 minutes at entry into service for up to a 420-minute 
maximum diversion time.
    The Airbus Model A350-900 series airplane is equipped with a 
braking system that affects the airplane's pivoting behavior. During 
pivoting the braking system inhibits braking on some wheels. Title 14 
Code of Federal Regulations (14 CFR) 25.503 and European Aviation 
Safety Agency (EASA) Certification Specification (CS) section 25.503, 
each specify limit loads due to pivoting, however, system effects are 
not taken into account.

Type Certification Basis

    Under Title 14, Code of Federal Regulations (14 CFR) 21.17, Airbus 
must show that the Model A350-900 series 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 because of a 
novel or unusual design feature, special conditions are prescribed 
under Sec.  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 Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model A350-900 series must comply with the fuel-vent 
and exhaust-emission requirements of 14 CFR part 34 and the noise-
certification requirements of 14 CFR part 36 and the FAA must issue a 
finding of regulatory adequacy under Sec.  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 Sec.  11.38, and they become part of the type-certification basis 
under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Airbus Model A350-900 series airplane will incorporate the 
following novel or unusual design features: a braking system that 
affects the airplane's pivoting behavior.

Discussion

    Within the Aviation Rulemaking Advisory Committee, the Loads and 
Dynamics Harmonization Working Group developed criteria for determining 
pivoting loads. The group recommended, for airplanes with more than two 
main landing gear units, a rational pivoting maneuver that takes into 
account the effects of the braking system and tire characteristics, in 
lieu of the current requirement. Although the

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Airbus Model A350-900 series airplane has two main landing gear units, 
EASA and the FAA propose to apply the same criteria on this airplane.
    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. 25-13-10-SC for Airbus 
Model A350-900 series airplanes was published in the Federal Register 
on October 29, 2013 (78FR64415). The Boeing Company submitted one 
comment, which stated that ``there is not a specific requirement to 
consider failure modes. Failure modes of the brake system that would 
cause brakes to be applied during pivoting should be investigated in 
accordance with the requirements relating to systems and structures 
interaction. We suggest that the FAA consider revising the proposal to 
include this specific requirement.''
    Failure modes of the braking system are addressed by a separate 
special-conditions document titled Interaction of Systems and 
Structures, published in the Federal Register on December 20, 2013 
(78FR76980). The Interaction of Systems and Structures special 
conditions requires that the effects of system failures be taken into 
account, and specifically addresses the pivoting requirement, Sec.  
25.503, and any special condition used in lieu of Sec.  25.503.
    This (i.e., current) special conditions document addresses loads 
associated with structural design not specific to a failure condition.

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.

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, 44704.

The Special Conditions

0
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 lieu of Sec.  25.503:
    1. The main landing gear and supporting structure must be designed 
for the loads induced by pivoting during ground maneuvers.
    a. The following rational pivoting maneuvers must be considered:
    i. Towing at the nose gear at the critical towing angle with no 
brakes applied, including cases with torque links disconnected; and 
separately,
    ii. Application of symmetrical or unsymmetrical forward thrust to 
aid pivoting, with or without braking by pilot action on the pedals.
    b. The airplane is assumed to be in static equilibrium, with the 
loads being applied at the ground contact points.
    c. The limit vertical load factor must be 1.0, and:
    i. For wheels with brakes applied, the coefficient of friction must 
be 0.8,
    ii. For wheels with brakes not applied, the ground tire reactions 
must be based on reliable tire data.

    Issued in Renton, Washington, on: April 25, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-13667 Filed 6-11-14; 8:45 am]
BILLING CODE 4910-13-P


