[Federal Register Volume 79, Number 148 (Friday, August 1, 2014)]
[Rules and Regulations]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-18176]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2013-0902; Special Conditions No. 25-521-SC]
Special Conditions: Airbus Model A350-900 Series Airplane;
Electronic Flight-Control System (EFCS) To Limit Pitch and Roll
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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 the electronic flight-control system (EFCS) that limits
pitch- and roll-attitude functions. 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 2, 2014.
FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and
Flightcrew Interface Branch, ANM-111, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98057-3356; telephone (425) 227-2011; facsimile (425) 227-
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
A special condition to supplement Sec. 25.143 concerning pitch and
roll limits was developed for the Airbus Model A320, A330, A340, and
A380 airplanes wherein performance of the limiting functions was
monitored throughout the flight-test program. The FAA expects similar
monitoring to take place during the A350 flight-test program to
substantiate the pitch- and roll-attitude limiting functions, and the
appropriateness of the chosen limits.
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-
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 final
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 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 series will incorporate the following
novel or unusual design features: an EFCS that, when operating in its
normal mode, will prevent airplane pitch attitudes greater than +30
degrees and less than -15 degrees, and roll angles greater than plus or
minus 67 degrees. In addition, positive spiral stability is introduced
for roll angles greater than 33 degrees at speeds below VMO/
MMO. At speeds greater than VMO and up to
VDF, maximum aileron-control force is limited to only 45
degrees maximum bank angle.
It is expected that high thrust-to-weight ratios provide the most
critical cases for the positive-pitch limit. A margin in pitch control
must be available to enable speed control in maneuvers such as climb
after takeoff, and balked landing climb. The pitch limit must not
impede likely maneuvering made necessary by collision avoidance
efforts. A negative-pitch limit must similarly not interfere with
collision-avoidance capability, or with attaining and maintaining
speeds near VMO/MMO for emergency descent.
Spiral stability, which is introduced above 33 degrees roll angle,
and the roll limit must not restrict attaining roll angles up to 66
degrees (approximately 2.5g level turn) with flaps up and 60 degrees
(approximately 2.0g level turn) with flaps down. The implementation of
this spiral stability requires a steady aileron-control force to
maintain a constant bank angle above 33 degrees. This force must not
require excessive pilot strength as stated in Sec. 25.143(f).
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
Discussion of Comments
Notice of proposed special conditions no. 25-13-25-SC for the
Airbus Model A350-900 airplane was published in the Federal Register on
November 12, 2013 (78 FR 67320). One comment supporting the special
conditions was received. These special conditions are adopted as
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.
This action affects only certain novel or unusual design features
on the Airbus Model A350-900 airplanes. It is not a rule of general
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
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
addition to Sec. 25.143, the following requirements apply:
1. The pitch-limiting function must not impede normal maneuvering
for pitch angles up to the maximum required for normal maneuvering,
including a normal all-engines-operating takeoff, plus a suitable
margin to allow for satisfactory speed control.
2. The pitch and roll limiting functions must not restrict or
prevent attaining pitch attitudes necessary for emergency maneuvering,
or roll angles up to 66 degrees with flaps up or 60 degrees with flaps
down. Spiral stability, which is introduced above 33 degrees roll
angle, must not require excessive pilot strength to achieve these roll-
limit angles. Other protections, which further limit the roll
capability under certain extreme angle-of-attack,
attitude, or high-speed conditions, are acceptable as long as they
allow at least 45 degrees of roll capability.
Issued in Renton, Washington, on July 11, 2014.
Acting Manager, Transport Airplane Directorate, Aircraft Certification
[FR Doc. 2014-18176 Filed 7-31-14; 8:45 am]
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