
[Federal Register Volume 79, Number 152 (Thursday, August 7, 2014)]
[Rules and Regulations]
[Pages 46173-46175]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-18659]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2014-0303; Special Conditions No. 25-561-SC]


Special Conditions: Airbus Model A350-900 Airplane; Operation 
Without Normal Electrical Power

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special condition; request for comments.

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SUMMARY: These special conditions are issued for the Airbus Model A350-
900 airplane. This airplane will have a novel or unusual design feature 
associated with operation without normal electrical power. 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: The effective date of these special conditions is August 7, 
2014. We must receive your comments by September 22, 2014.

ADDRESSES: Send comments identified by docket number FAA-2014-0303 
using any of the following methods:
     Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending 
your comments electronically.
    Mail: Send comments to Docket Operations, M-30, U.S. Department of 
Transportation (DOT), 1200 New Jersey Avenue SE., Room W12-140, West 
Building Ground Floor, Washington, DC, 20590-0001.
    Hand Delivery or Courier: Take comments to Docket Operations in 
Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through 
Friday, except federal holidays.
    Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov/, including any personal 
information the commenter provides. Using the search function of the 
docket Web site, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov/.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov/ at any time. Follow the online instructions 
for accessing the docket or go to the Docket Operations in Room W12-140 
of the West Building Ground Floor at 1200 New Jersey Avenue SE., 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except federal holidays.

FOR FURTHER INFORMATION CONTACT: Nazih Khaouly, FAA, Airframe and 
Flightcrew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; telephone (425) 227-2432; facsimile (425) 227-
1320.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and 
opportunity for prior public comment on, these special conditions is 
impracticable because these procedures would significantly delay 
issuance of the design approval and thus delivery of the affected 
aircraft. In addition, the substance of these special conditions has 
been subject to the public-comment process in several prior instances 
with no substantive comments received. The FAA therefore finds that 
good cause exists for making these special conditions effective upon 
publication in the Federal Register.

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special conditions, explain the 
reason for any recommended change, and include supporting data.
    We will consider all comments we receive by the closing date for 
comments. We may change these special conditions based on the comments 
we receive.

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 Airbus 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.
    The Airbus Model A350-900 airplane fly-by-wire control system 
requires a continuous source of electrical power to maintain an 
operable flight-control system. The current rule, Title 14, Code of 
Federal Regulations (14 CFR) 25.1351(d), Amendment 25-72, requires safe 
operation under visual flight rules (VFR) conditions for at least five 
minutes after loss of all normal electrical power. This rule was 
structured around a traditional design utilizing mechanical control 
cables for flight control while the crew took time to sort out the 
electrical failure, start engine(s) if necessary, and re-establish some 
of the electrical-power-generation capability.
    To maintain the same level of safety associated with traditional 
designs, Airbus Model A350-900 airplanes must be designed for operation 
with the normal sources of engine- or Auxiliary Power Unit (APU)-
generated electrical power inoperative. Service experience has shown 
that loss of all electrical power from the airplane's engine and APU-
driven generators is not extremely improbable. Therefore, it must be 
shown that the airplane is capable of recovering adequate primary 
electrical-power generation for safe flight and landing with the use of 
its emergency electrical-power systems. These emergency electrical-
power systems must be able to

[[Page 46174]]

power loads that are essential for continued safe flight and landing.

Type Certification Basis

    Under 14 CFR 21.17, Airbus must show that the Airbus 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 Airbus Model A350-900 airplane 
because of a novel or unusual design feature, special conditions are 
prescribed under Sec.  21.16. These special conditions are an extension 
of part 25 due to the inadequacies of the existing part 25 requirements 
to address loss of all normal electrical power.
    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 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 Airbus Model A350-900 airplane must be shown to 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 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 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: The capability of continued safe flight and 
landing that are dependent on one or more continuous sources of 
electrical power.
    Due to rapid improvements in airplane technology, the applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for these design features. These special conditions for the 
Airbus Model A350-900 airplane 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.
    In addition to an electronic flight-control system, a number of 
systems that have traditionally been mechanically operated have been 
implemented as electrically powered systems on the Model A350-900 
airplane. The criticality of some of these systems is such that their 
failure will either reduce the capability of the airplane or the 
ability of the crew to cope with adverse operating conditions, or 
prevent continued safe flight and landing of the airplane.

Discussion

    The current rule, 14 CFR 25.1351(d), Amendment 25-72, requires safe 
operation under VFR conditions for at least five minutes after loss of 
all normal electrical power. This rule was structured around 
traditional airplane designs that use mechanical control cables and 
linkages for flight control. These manual controls allow the flightcrew 
to maintain aerodynamic control of the airplane for an indefinite time 
after loss of all electrical power. Under these conditions, the 
mechanical flight-control system provides the flightcrew with the 
ability to fly the airplane while attempting to identify the cause of 
the electrical failure, start the engine(s) if necessary, and 
reestablish some of the electrical-power-generation capability, if 
possible.
    To maintain the same level of safety associated with traditional 
designs, the Airbus Model A350-900 airplane must be designed for 
operation with the normal sources of engine- and APU-generated 
electrical power inoperative. The FAA has identified electrically 
powered functions required to safely complete a maximum ETOPS diversion 
as another potential catastrophic effect from the loss of all normal 
electrical power. Service history has shown that analytical means have 
not been accurate at anticipating common-cause failures, nor have such 
means been accurate at predicting that loss of all normal sources of 
electrical power is extremely improbable.
    Airbus must demonstrate that the airplane is capable of recovering 
adequate primary electrical-power generation during ETOPS, and for 
continued safe flight and landing. An alternative source of electrical 
power would have to be provided for the time necessary to restore the 
minimum power-generation capability necessary during ETOPS, and for 
continued safe flight and landing.
    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.

Applicability

    As discussed above, these special conditions are applicable to the 
Airbus Model A350-900. Should Airbus apply at a later date 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 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 A350-900 airplanes.
    In lieu of the requirements of 14 CFR 25.1351(d) the following 
special conditions apply:
    1. The applicant must show by test, or a combination of test and 
analysis, that the airplane is capable of continued safe flight and 
landing with all normal sources of engine- and APU-generated electrical 
power inoperative as prescribed by paragraphs 1.a. and 1.b. below. For 
purposes of these special conditions, normal sources of electrical 
power generation do not include any alternate power sources such as 
batteries, ram-air turbine (RAT), or independent power systems such as 
the flight-control permanent magnet generating system. In showing 
capability for continued safe flight and landing, consideration must be 
given to systems capability, effects on flightcrew workload and 
operating conditions, and the physiological needs of the flightcrew and 
passengers for the longest diversion time for which approval is sought.
    a. Common mode failures, cascading failures, and zonal physical 
threats must be considered in showing compliance with this requirement.
    b. In showing compliance with this requirement, the ability to 
restore operation of portions of the electrical-power generation and 
distribution system may be considered if it can be shown that 
unrecoverable loss of those portions of the system is extremely 
improbable. An alternative source of electrical power must be provided 
for the time required to restore the minimum electrical-power 
generation capability required for continued safe

[[Page 46175]]

flight and landing. Unrecoverable loss of all engines may be excluded 
when showing that unrecoverable loss of critical portions of the 
electrical system is extremely improbable.
    2. Regardless of any electrical generation-and-distribution system-
recovery capability shown under paragraph 1, above, sufficient 
electrical-system capability must be provided to--
    a. allow time to descend, with all engines inoperative, at the 
speed that provides the best glide distance, from the maximum operating 
altitude to the top of the engine-restart envelope, and
    b. subsequently allow multiple start attempts of the engines and 
APU. This capability must be provided in addition to the electrical 
capability required by existing part 25 requirements related to 
operation with all engines inoperative.
    3. The electrical energy the airplane uses in descending with 
engines inoperative, from the maximum operating altitude at the best 
glide speed, and in making multiple attempts to start the engines and 
APU, must be considered when showing compliance with paragraphs 1 and 2 
of these special conditions, and with existing 14 CFR part 25 
requirements related to continued safe flight and landing.

    Issued in Renton, Washington, on July 23, 2014.
John P. Piccola, Jr.,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-18659 Filed 8-6-14; 8:45 am]
BILLING CODE 4910-13-P


