Special Conditions: Airbus, Model A350-900 Series Airplane; Lateral Trim Function Through Differential Flap Setting, 1339-1341 [2014-00105]
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Federal Register / Vol. 79, No. 5 / Wednesday, January 8, 2014 / Proposed Rules
characteristics for what are considered
survivable crash conditions. The
proposed special conditions are
necessary to ensure a level of safety
equivalent to that provided by 14 CFR
part 25.
Discussion
Factors in crash survivability are
retention of items of mass, maintenance
of occupant emergency egress paths,
maintenance of acceptable acceleration
and loads experienced by the occupants,
and maintenance of a survivable
volume. To provide the same level of
safety as exists with conventional
airplane construction, Airbus should
show that the Model A350–900 series
airplanes have sufficient
crashworthiness capabilities under
foreseeable survivable impact events. To
show this, Airbus should evaluate the
impact response characteristics of the
Model A350–900 series airplane to
ensure that its crashworthiness
characteristics are not significantly
different from those of a similarly sized
airplane built from traditionally used
metallic materials.
In their evaluation of the Model
A350–900 series airplane response to an
impact event, Airbus should
demonstrate that the structural behavior
is similar to that expected from a
metallic airframe of similar size to the
Model A350–900, or incorporate
mitigating design features that provide a
similar level of safety.
Airbus should demonstrate either
through analysis using validated
analytical tools or by direct test
evidence that the crash dynamics of the
A350 fuselage structure provides a level
of occupant protection consistent with
previously certificated large transport
category airplanes.
mstockstill on DSK4VPTVN1PROD with PROPOSALS
Applicability
As discussed above, these proposed
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 proposed
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:
VerDate Mar<15>2010
16:18 Jan 07, 2014
Jkt 232001
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation
Administration (FAA) proposes the
following special conditions as part of
the type certification basis for Airbus
Model A350–900 series airplanes.
The Airbus Model A350–900 series
airplanes must provide an equivalent
level of occupant safety and
survivability to that provided by
previously certificated wide-body
transports of similar size under
foreseeable survivable impact events for
the following four criteria. In order to
demonstrate an equivalent level of
occupant safety and survivability, the
applicant must demonstrate that Model
A350–900 series airplanes meet the
following criteria for a range of airplane
vertical descent velocities up to 30 ft/
sec.
1. Retention of items of mass. The
occupants, i.e., passengers, flight
attendants, and flightcrew, must be
protected during the impact event from
release of seats, overhead bins, and
other items of mass due to the impact
loads and resultant structural
deformation of the supporting airframe
and floor structures. The applicant must
show that loads due to the impact event
and resultant structural deformation of
the supporting airframe and floor
structure at the interface of the airplane
structure to seats, overhead bins, and
other items of mass are comparable to
those of previously certificated widebody transports of similar size for the
range of descent velocities stated above.
The attachments of these items need not
be designed for static emergency
landing loads in excess of those defined
in § 25.561 if impact response
characteristics of the Airbus Model
A350–900 series airplanes yield load
factors at the attach points that are
comparable to those for a previously
certificated wide-body transport
category airplane.
2. Maintenance of acceptable
acceleration and loads experienced by
the occupants. The applicant must show
that the impact response characteristics
of the Airbus Model A350–900 series
airplane, specifically the vertical
acceleration levels experienced at the
seat/floor interface and loads
experienced by the occupants during
the impact events, are consistent with
those found in § 25.562(b) or with levels
expected for a previously certificated
wide-body transport category airplane
for the conditions stated above.
3. Maintenance of a survivable
volume. For the conditions stated above,
the applicant must show that all areas
PO 00000
Frm 00006
Fmt 4702
Sfmt 4702
1339
of the airplane occupied for takeoff and
landing provide a survivable volume
comparable to that of previously
certificated wide-body transports of
similar size during and after the impact
event. This means that structural
deformation will not result in
infringement of the occupants’ normal
living space so that passenger
survivability will not be significantly
affected.
4. Maintenance of occupant
emergency egress paths. The evacuation
of occupants must be comparable to that
from a previously certificated widebody transport of similar size. To show
this, the applicant must show that the
suitability of the egress paths, as
determined following the vertical
impact events, is comparable to the
suitability of the egress paths of a
comparable, certificated wide-body
transport, as determined following the
same vertical impact events.
Issued in Renton, Washington, on October
22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. 2014–00104 Filed 1–7–14; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2013–0911; Notice
No. 25–13–22–SC]
Special Conditions: Airbus, Model
A350–900 Series Airplane; Lateral Trim
Function Through Differential Flap
Setting
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed special
conditions.
AGENCY:
This action proposes special
conditions for the Airbus Model A350–
900 series airplanes. These airplanes
will have a novel or unusual design
feature associated with a lateral trim
function that deploys flaps
asymmetrically for airplane lateral trim
control. This function replaces the
traditional method of providing airplane
lateral trim over a small range through
flap and aileron mechanical rigging. The
applicable airworthiness regulations do
not contain adequate or appropriate
safety standards for this design feature.
These proposed special conditions
contain the additional safety standards
that the Administrator considers
necessary to establish a level of safety
SUMMARY:
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08JAP1
mstockstill on DSK4VPTVN1PROD with PROPOSALS
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Federal Register / Vol. 79, No. 5 / Wednesday, January 8, 2014 / Proposed Rules
equivalent to that established by the
existing airworthiness standards.
DATES: Send your comments on or
before February 24, 2014.
ADDRESSES: Send comments identified
by docket number FAA–2013–0911
using any of the following methods:
• Federal eRegulations Portal: Go to
https://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 https://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 https://DocketsInfo.
dot.gov/.
Docket: Background documents or
comments received may be read at
https://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:
Robert C. Jones, FAA, Propulsion/
Mechanical Systems, ANM–112,
Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington 98057–3356;
telephone (425) 227–1234; facsimile
(425) 227–1320.
SUPPLEMENTARY INFORMATION:
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
VerDate Mar<15>2010
16:18 Jan 07, 2014
Jkt 232001
specific portion of the special
conditions, explain the reason for any
recommended change, and include
supporting data.
We will consider all comments we
receive on or before the closing date for
comments. We may change these
proposed 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 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 has a
conventional layout with twin wingmounted 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 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 to be certified for extended
operations (ETOPS) beyond 180 minutes
at entry into service for up to a 420minute maximum diversion time.
On conventional airplanes, small
lateral airplane asymmetries have
typically been addressed through flap
and aileron rigging (e.g., using shims).
On Model A350–900 series airplanes, an
order for asymmetric flap deployment
will be computed by the primary flight
control system as a function of the
aileron position. The current
airworthiness standards do not contain
adequate safety standards for
asymmetric use of the flaps as proposed
for Airbus Model A350–900 series
airplanes. Special conditions are needed
to account for the aspects of a function
used to command an intended flap
asymmetry. The lateral trim function is
intended to be performed once during
climb and once during cruise to
compensate for small airplane lateral
asymmetries.
The lateral trim function is not a trim
control system in the conventional
sense as it has no pilot interface and is
not governed by § 25.677. In fact some
fly-by-wire airplanes have no pilot
operated lateral trim at all. The lateral
trim function is simply an additional
fly-by-wire flight control function that
nulls small roll asymmetries in certain
flight phases with small asymmetric flap
deployments. Although the function
operates under normal conditions
within the small range of the traditional
PO 00000
Frm 00007
Fmt 4702
Sfmt 4702
rigging, there may be failure cases
leading to a significant out of range
asymmetric flap condition. An
asymmetry threshold will protect the
system against excessive flap
asymmetry.
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
§ 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 novel or unusual
design feature, the proposed special
conditions would also apply to the other
model under § 21.101.
In addition to the applicable
airworthiness regulations and proposed
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
§ 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 § 11.38,
and they become part of the typecertification basis under § 21.17(a)(2).
Novel or Unusual Design Features
The Airbus Model A350–900 series
will incorporate the following novel or
unusual design features: the asymmetric
use of flaps to address lateral trim
which is not adequately addressed by
§ 25.701.
Discussion
Title 14 Code of Federal Regulations
(14 CFR) part 25 § 25.701(a) requires
that unless the airplane has safe flight
characteristics with the flaps or slats
retracted on one side and extended on
the other, flap and slat surfaces must be
synchronized by either a mechanical
interconnection or any equivalent
means that has the same integrity.
Synchronization is interpreted to mean
that flap movement is symmetrical
throughout the full range of flap motion.
Because the lateral trim function
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Federal Register / Vol. 79, No. 5 / Wednesday, January 8, 2014 / Proposed Rules
intentionally creates asymmetric flap
motions, the flap system installation of
the Model A350–900 series does not
meet the requirement of § 25.701(a) and
(d).
Issued in Renton, Washington, on October
22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
Applicability
As discussed above, these proposed
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 proposed
special conditions would apply to that
model as well.
[FR Doc. 2014–00105 Filed 1–7–14; 8:45 am]
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:
mstockstill on DSK4VPTVN1PROD with PROPOSALS
The Proposed Special Conditions
Accordingly, the Federal Aviation
Administration (FAA) proposes the
following special conditions as part of
the type certification basis for Airbus
Model A350–900 series airplanes.
1. Lateral Trim Function through
Differential Flap Setting.
Current airworthiness standards,
specifically § 25.701, do not contain
adequate safety standards for the
proposed design. In lieu of the
requirements of § 25.701(a) and (d) for
the lateral trim function, the following
special condition is proposed:
a. Airbus must demonstrate that an
unsafe condition is not created by using
the flaps asymmetrically,
b. The degree of acceptable
asymmetry must be defined and
justified for all flight phases with
respect to:
• § 25.701(b) and (c), with the worst
case asymmetric flap configurations,
and
• providing equivalent protection
against excess asymmetry in the same
manner as § 25.701 provides to systems
that are synchronized or use another
equivalent means to prevent asymmetry.
c. This lateral trim function is a flight
control system and therefore must show
compliance to both general system
requirements as well as general flight
control requirements. Therefore, the
function must be demonstrated not to
embody, where practicable, significant
latent failures.
16:18 Jan 07, 2014
Jkt 232001
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 71
[Docket No. FAA–2013–0175; Airspace
Docket No. 13–AGL–12]
Proposed Amendment of Class D and
Class E Airspace; Traverse City, MI
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
This action proposes to
amend Class D and Class E airspace at
Traverse City, MI. Additional controlled
airspace is necessary to accommodate
new Standard Instrument Approach
Procedures (SIAP) at Cherry Capital
Airport. Geographic coordinates of the
airport also would be adjusted. The
FAA is taking this action to enhance the
safety and management of Instrument
Flight Rules (IFR) operations for SIAPs
at the airport.
DATES: Comments must be received on
or before February 24, 2014.
ADDRESSES: Send comments on this
proposal to the U.S. Department of
Transportation, Docket Operations, 1200
New Jersey Avenue SE., West Building
Ground Floor, Room W12–140,
Washington, DC 20590–0001. You must
identify the docket number FAA–2013–
0175/Airspace Docket No. 13–AGL–12,
at the beginning of your comments. You
may also submit comments through the
Internet at https://www.regulations.gov.
You may review the public docket
containing the proposal, any comments
received, and any final disposition in
person in the Dockets Office between 9
a.m. and 5 p.m., Monday through
Friday, except Federal holidays. The
Docket Office (telephone 1–800–647–
5527), is on the ground floor of the
building at the above address.
FOR FURTHER INFORMATION CONTACT:
Scott Enander, Central Service Center,
Operations Support Group, Federal
Aviation Administration, Southwest
Region, 2601 Meacham Blvd., Fort
Worth, TX 76137; telephone: (817) 321–
7716.
SUPPLEMENTARY INFORMATION:
SUMMARY:
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
VerDate Mar<15>2010
BILLING CODE 4910–13–P
PO 00000
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Fmt 4702
Sfmt 4702
1341
Comments Invited
Interested parties are invited to
participate in this proposed rulemaking
by submitting such written data, views,
or arguments, as they may desire.
Comments that provide the factual basis
supporting the views and suggestions
presented are particularly helpful in
developing reasoned regulatory
decisions on the proposal. Comments
are specifically invited on the overall
regulatory, aeronautical, economic,
environmental, and energy-related
aspects of the proposal.
Communications should identify both
docket numbers and be submitted in
triplicate to the address listed above.
Commenters wishing the FAA to
acknowledge receipt of their comments
on this notice must submit with those
comments a self-addressed, stamped
postcard on which the following
statement is made: ‘‘Comments to
Docket No. FAA–2013–0175/Airspace
Docket No. 13–AGL–12.’’ The postcard
will be date/time stamped and returned
to the commenter.
Availability of NPRMs
An electronic copy of this document
may be downloaded through the
Internet at https://www.regulations.gov.
Recently published rulemaking
documents can also be accessed through
the FAA’s Web page at https://
www.faa.gov/airports_airtraffic/
air_traffic/publications/
airspace_amendments/.
You may review the public docket
containing the proposal, any comments
received and any final disposition in
person in the Dockets Office (see
ADDRESSES section for address and
phone number) between 9 a.m. and 5
p.m., Monday through Friday, except
Federal holidays. An informal docket
may also be examined during normal
business hours at the office of the
Central Service Center, 2601 Meacham
Blvd., Fort Worth, TX 76137.
Persons interested in being placed on
a mailing list for future NPRMs should
contact the FAA’s Office of Rulemaking
(202) 267–9677, to request a copy of
Advisory Circular No. 11–2A, Notice of
Proposed Rulemaking Distribution
System, which describes the application
procedure.
The Proposal
This action proposes to amend Title
14, Code of Federal Regulations (14
CFR), part 71 by amending Class D
airspace, Class E airspace designated as
a surface area, and Class E airspace
extending upward from 700 feet above
the surface to accommodate new
standard instrument approach
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]]>Agencies
[Federal Register Volume 79, Number 5 (Wednesday, January 8, 2014)]
[Proposed Rules]
[Pages 1339-1341]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-00105]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2013-0911; Notice No. 25-13-22-SC]
Special Conditions: Airbus, Model A350-900 Series Airplane;
Lateral Trim Function Through Differential Flap Setting
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
-----------------------------------------------------------------------
SUMMARY: This action proposes special conditions for the Airbus Model
A350-900 series airplanes. These airplanes will have a novel or unusual
design feature associated with a lateral trim function that deploys
flaps asymmetrically for airplane lateral trim control. This function
replaces the traditional method of providing airplane lateral trim over
a small range through flap and aileron mechanical rigging. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. These proposed
special conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
[[Page 1340]]
equivalent to that established by the existing airworthiness standards.
DATES: Send your comments on or before February 24, 2014.
ADDRESSES: Send comments identified by docket number FAA-2013-0911
using any of the following methods:
Federal eRegulations Portal: Go to https://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 https://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 https://DocketsInfo.dot.gov/.
Docket: Background documents or comments received may be read at
https://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: Robert C. Jones, FAA, Propulsion/
Mechanical Systems, ANM-112, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone (425) 227-1234; facsimile (425) 227-1320.
SUPPLEMENTARY INFORMATION:
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 on or before the closing
date for comments. We may change these proposed 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 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 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 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 to be certified for extended operations (ETOPS)
beyond 180 minutes at entry into service for up to a 420-minute maximum
diversion time.
On conventional airplanes, small lateral airplane asymmetries have
typically been addressed through flap and aileron rigging (e.g., using
shims). On Model A350-900 series airplanes, an order for asymmetric
flap deployment will be computed by the primary flight control system
as a function of the aileron position. The current airworthiness
standards do not contain adequate safety standards for asymmetric use
of the flaps as proposed for Airbus Model A350-900 series airplanes.
Special conditions are needed to account for the aspects of a function
used to command an intended flap asymmetry. The lateral trim function
is intended to be performed once during climb and once during cruise to
compensate for small airplane lateral asymmetries.
The lateral trim function is not a trim control system in the
conventional sense as it has no pilot interface and is not governed by
Sec. 25.677. In fact some fly-by-wire airplanes have no pilot operated
lateral trim at all. The lateral trim function is simply an additional
fly-by-wire flight control function that nulls small roll asymmetries
in certain flight phases with small asymmetric flap deployments.
Although the function operates under normal conditions within the small
range of the traditional rigging, there may be failure cases leading to
a significant out of range asymmetric flap condition. An asymmetry
threshold will protect the system against excessive flap asymmetry.
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 novel or
unusual design feature, the proposed special conditions would also
apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and
proposed 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 will incorporate the following
novel or unusual design features: the asymmetric use of flaps to
address lateral trim which is not adequately addressed by Sec. 25.701.
Discussion
Title 14 Code of Federal Regulations (14 CFR) part 25 Sec.
25.701(a) requires that unless the airplane has safe flight
characteristics with the flaps or slats retracted on one side and
extended on the other, flap and slat surfaces must be synchronized by
either a mechanical interconnection or any equivalent means that has
the same integrity. Synchronization is interpreted to mean that flap
movement is symmetrical throughout the full range of flap motion.
Because the lateral trim function
[[Page 1341]]
intentionally creates asymmetric flap motions, the flap system
installation of the Model A350-900 series does not meet the requirement
of Sec. 25.701(a) and (d).
Applicability
As discussed above, these proposed 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 proposed 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 Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Airbus Model A350-900 series airplanes.
1. Lateral Trim Function through Differential Flap Setting.
Current airworthiness standards, specifically Sec. 25.701, do not
contain adequate safety standards for the proposed design. In lieu of
the requirements of Sec. 25.701(a) and (d) for the lateral trim
function, the following special condition is proposed:
a. Airbus must demonstrate that an unsafe condition is not created
by using the flaps asymmetrically,
b. The degree of acceptable asymmetry must be defined and justified
for all flight phases with respect to:
Sec. 25.701(b) and (c), with the worst case asymmetric
flap configurations, and
providing equivalent protection against excess asymmetry
in the same manner as Sec. 25.701 provides to systems that are
synchronized or use another equivalent means to prevent asymmetry.
c. This lateral trim function is a flight control system and
therefore must show compliance to both general system requirements as
well as general flight control requirements. Therefore, the function
must be demonstrated not to embody, where practicable, significant
latent failures.
Issued in Renton, Washington, on October 22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2014-00105 Filed 1-7-14; 8:45 am]
BILLING CODE 4910-13-P
