Document ID: FAA-2013-0900-0002
Agency: faa
Document Type: Rule
Title: Special Conditions: Airbus Model A350-900 airplane; General Limiting Requirements
Posted Date: 2014-09-22T04:00Z

[Federal Register Volume 79, Number 183 (Monday, September 22, 2014)]
[Rules and Regulations]
[Pages 56485-56486]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-22340]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2013-0900; Special Conditions No. 25-540-SC]

Special Conditions: Airbus Model A350-900 airplane; General 
Limiting Requirements

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 
airplanes. These airplanes will have a novel or unusual design feature 
associated with general limiting requirements of its flight-envelope 
protection features. 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 September 22, 2014.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and 
Flightcrew Interface, ANM-111, Transport Airplane Directorate, Aircraft 
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone (425) 227-2011; facsimile (425) 227-1320.

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 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 airplane 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.

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 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 airplane 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 airplane 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. 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 airplane incorporates the following novel 
or unusual design features: General limiting requirements for the 
flight-envelope protection system.

Discussion

    These special conditions, and the following that pertain to flight-
envelope protection, present general limiting requirements for all the 
unique flight-envelope protection features of the basic Model A350 
airplane's electronic flight-control system (EFCS) design. Current 
regulations do not address these types of protection features. The 
general limiting requirements are necessary to ensure a smooth 
transition from normal flight to the protection mode and adequate 
maneuver capability. The general limiting requirements also ensure that 
the structural limits of the airplane are not exceeded. Furthermore, 
failure of the flight-envelope protection feature must not create 
hazardous flight conditions. Envelope-protection parameters include 
angle of attack, normal load factor, bank angle, pitch angle, and 
speed. To accomplish these envelope protections, one or more 
significant changes occur in the EFCS control laws as the normal 
flight-

[[Page 56486]]

envelope limit is approached or exceeded.
    Flight-envelope protection is the subject of several special 
conditions for the A350. Each specific type of envelope protection is 
addressed individually, but some requirements are common to all 
limiting systems and are therefore put forth as general limiting 
requirements.
    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. 25-12-08-SC for Airbus 
Model A350-900 airplanes was published in the Federal Register on 
January 14, 2014 (79 FR 2387). 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 airplane. 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 standard practice, the effective date of final special 
conditions would be 30 days after the date of publication in the 
Federal Register; however, as the certification date for the Airbus 
Model A350-900 airplane is imminent, the FAA finds that good cause 
exists to make these special conditions effective upon publication.

Conclusion

    This action affects only certain novel or unusual design features 
on the Airbus Model A350-900 airplane. 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 350-900 airplanes.

General Limiting Requirements

    a. Onset characteristics of each flight-envelope protection feature 
must be smooth, appropriate to the phase of flight and type of 
maneuver, and not in conflict with the ability of the pilot to 
satisfactorily change airplane flight path, speed, or attitude as 
needed.
    b. Limit values of protected flight parameters (and, if applicable, 
associated warning thresholds) must be compatible with the following:
    (1) Airplane structural limits,
    (2) Required safe and controllable maneuvering of the airplane, and
    (3) Margins to critical conditions. Unsafe flight characteristics/
conditions must not result if dynamic maneuvering, airframe, and system 
tolerances (both manufacturing and in-service), and non-steady 
atmospheric conditions, in any appropriate combination and phase of 
flight, can produce a limited flight parameter beyond the nominal 
design limit value.
    c. The airplane must be responsive to intentional dynamic 
maneuvering to within a suitable range of the parameter limit. Dynamic 
characteristics such as damping and overshoot must also be appropriate 
for the flight-maneuver and limit parameter in question.
    d. When simultaneous envelope limiting is engaged, adverse coupling 
or adverse priority must not result.

Failure States

    EFCS failures (including sensor) must not result in a condition 
where a parameter is limited to such a reduced value that safe and 
controllable maneuvering is no longer available. The crew must be 
alerted by suitable means if any change in envelope limiting or 
maneuverability is produced by single or multiple failures of the EFCS 
not shown to be extremely improbable.

    Issued in Renton, Washington, on August 27, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-22340 Filed 9-19-14; 8:45 am]
BILLING CODE 4910-13-P