Proposed Rule2022-07228
Special Conditions: Airbus Model A321neoXLR Airplane; Passenger Protection From External Fire
Primary source
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Published
April 6, 2022
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
This action proposes special conditions for the Airbus Model A321neoXLR airplane. This airplane will have a novel or unusual design feature when compared to the technology envisaged by the airworthiness standards for transport category airplanes. This design feature is an integral rear center tank (RCT). 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 equivalent to that established by the existing airworthiness standards.
Full Text
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<title>Federal Register, Volume 87 Issue 66 (Wednesday, April 6, 2022)</title>
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[Federal Register Volume 87, Number 66 (Wednesday, April 6, 2022)]
[Proposed Rules]
[Pages 19811-19813]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-07228]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2021-0891; Notice No. 25-21-04-SC]
Special Conditions: Airbus Model A321neoXLR Airplane; Passenger
Protection From External Fire
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the Airbus Model
A321neoXLR airplane. This airplane will have a novel or unusual design
feature when compared to the technology envisaged by the airworthiness
standards for transport category airplanes. This design feature is an
integral rear center tank (RCT). 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 equivalent to that established by the
existing airworthiness standards.
DATES: Send comments on or before May 23, 2022.
ADDRESSES: Send comments identified by Docket No. FAA-2021-0891 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="http://www.regulations.gov/">http://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> 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.
<bullet> 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.
<bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: Except for Confidential Business Information (CBI) as
described in the following paragraph, and other information as
described in 14 CFR 11.35, the FAA will post all comments received
without change to <a href="http://www.regulations.gov/">http://www.regulations.gov/</a>, including any personal
information you provide. The FAA will also post a report summarizing
each substantive verbal contact received about this proposal.
Confidential Business Information: Confidential Business
Information (CBI) is commercial or financial information that is both
customarily and actually treated as private by its owner. Under the
Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from
public disclosure. If your comments responsive to this Notice contain
commercial or financial information that is customarily treated as
private, that you actually treat as private, and that is relevant or
responsive to this Notice, it is important that you clearly designate
the submitted comments as CBI. Please mark each page of your submission
containing CBI as ``PROPIN.'' The FAA will treat such marked
submissions as confidential under the FOIA, and the indicated comments
will not be placed in the public docket of this Notice. Submissions
containing CBI should be sent to Shannon Lennon, Human Machine
Interface, AIR-626, Technical Innovation Policy Branch, Policy and
Innovation Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3209; email <a href="/cdn-cgi/l/email-protection#95e6fdf4fbfbfafbbbf9f0fbfbfafbd5f3f4f4bbf2fae3"><span class="__cf_email__" data-cfemail="c8bba0a9a6a6a7a6e6a4ada6a6a7a688aea9a9e6afa7be">[email protected]</span></a>. Comments
the FAA receives, which are not specifically designated as CBI, will be
placed in the public docket for this rulemaking.
Docket: Background documents or comments received may be read at
<a href="http://www.regulations.gov/">http://www.regulations.gov/</a> at any time. Follow the online instructions
for accessing the docket or go 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.
FOR FURTHER INFORMATION CONTACT: Shannon Lennon, Human Machine
Interface, AIR-626, Technical Innovation Policy Branch, Policy and
Innovation Division, Aircraft Certification Service, Federal Aviation
Administration, 2200 South 216th Street, Des Moines, Washington 98198;
telephone and fax 206-231-3209; email <a href="/cdn-cgi/l/email-protection#1d6e757c73737273337178737372735d7b7c7c337a726b"><span class="__cf_email__" data-cfemail="2a59424b4444454404464f444445446a4c4b4b044d455c">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites 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
[[Page 19812]]
recommended change, and include supporting data.
The FAA will consider all comments received by the closing date for
comments. The FAA may change these special conditions based on the
comments received.
Background
On September 16, 2019, Airbus applied for an amendment to Type
Certificate No. A28NM to include the new Model A321neoXLR airplane. The
Model A321neoXLR airplane, which is a derivative of the Model
A321neoACF airplane currently approved under Type Certificate No.
A28NM, is a twin-engine transport category aircraft that seats 244
passengers and has a maximum takeoff weight of 202,000 lbs.
Type Certification Basis
Under the provisions of title 14, Code of Federal Regulations (14
CFR) 21.101, Airbus must show that the Model A321neoXLR airplane meets
the applicable provisions of the regulations listed in Type Certificate
No. A28NM, or the applicable regulations in effect on the date of
application for the change, except for earlier amendments as agreed
upon by the FAA.
If the Administrator finds that the applicable airworthiness
regulations (e.g., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Airbus Model A321NeoXLR airplane
because of a novel or unusual design feature, special conditions are
prescribed under the provisions of 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, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, these 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 A321NeoXLR 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 issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.101.
Novel or Unusual Design Feature
The Airbus Model A321NeoXLR airplane will incorporate the following
novel or unusual design feature:
An integral RCT.
Discussion
The proposed Airbus Model A321neoXLR incorporates an integral RCT.
This tank is a ``center'' fuel tank, in that would, if approved, be
located in the airplane fuselage rather than in its wings. The tank is
a ``rear'' tank, that would be located aft of the wheel bay; it would
be in an area of the lower fuselage that partially replaces the aft
cargo compartment of the airplane from which this proposed model is
derived. The top of the tank would be directly below the floor of the
passenger cabin. The fuel tank would be ``integral'' to the airplane,
in that its walls would be part of the airplane structure. The exterior
skin of the airplane fuselage would constitute part of the walls of the
fuel tank, and these areas would lack the thermal/acoustic insulation
that usually lines the exterior skin of an airplane fuselage.
This proposed design was not envisaged by the FAA's regulatory
requirements for insulation installations on transport category
airplanes. 14 CFR 25.856(b) requires all thermal/acoustic insulation in
the lower half of the airplane fuselage and their installation to
comply with the flame penetration resistance test of Appendix F Part
VII. The FAA adopted Sec. 25.856(b) to raise the level of post-crash
fire safety on transport category airplanes. Part VII of Appendix F
requires a stringent test method for all thermal/acoustic insulation
proposed for installation in the lower half of the fuselage. The FAA's
intent in imposing this requirement was to ensure that this insulation
provides an additional barrier between the occupants and an external
post-crash fire, especially a fire resulting from a pool of spilled
aviation fuel.\1\ This barrier extends the time available for
evacuation.
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\1\ See pg. 2 of FAA Advisory Circular 25.856-2A, Installation
of Thermal/Acoustic Insulation for Burnthrough Protection (Jul. 29,
2008), available at <a href="http://drs.faa.gov">drs.faa.gov</a>.
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While the rule applies to the thermal/acoustic insulation that an
applicant proposes as part of their design, it does not require
applicants to install such insulation. Since the fuselage skins of the
lower half of transport category airplanes are generally insulated, and
were at the time these standards were developed, the FAA considered
this approach to be sufficient to ensure safety. The rulemaking also
noted, however, that if applicants began to propose designs that
omitted this thermal/acoustic insulation, the FAA would revisit the
need for a specific fuselage burnthrough standard.\2\
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\2\ Improved Flammability Standards for Thermal/Acoustic
Insulation Materials Used In Transport Category Airplanes, 68 FR
45046, 45049 (Jul. 31, 2003).
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Thus, since this proposed design will lack thermal/acoustic
insulation under the fuselage skin in the area of the fuel tank,
current FAA regulations do not ensure that it will provide a continuous
flame penetration (burnthrough) resistant barrier between the
passengers and an external fire, nor that it will provide enough
protection, against an external post-crash fire, to allow time for
passengers to evacuate.
According to Airbus, its proposed design does not allow for
compliant thermal/acoustic insulation to be placed beneath the cabin
floor. This large volume of unheated liquid (fuel), directly below the
floor of the passenger cabin, would, without mitigation, create a `cold
feet' effect for the passengers above it. Therefore, Airbus plans to
install insulation panels between the fuel tank and the cabin floor,
for comfort reasons. These insulation panels would normally be required
to meet Sec. 25.856(b). However, Airbus states that it is technically
not feasible to install thermal/acoustic insulation that complies with
Sec. 25.856(b), due to the lack of space in this area, and the need to
keep nearby decompression panels free of blockages and ensure adequate
ventilation.
To address the assumption in the FAA's current flammability
standards that proposed airplane designs would include thermal/acoustic
insulation in the lower fuselage, and to ensure that this proposed
design does not reduce the time available for passenger evacuation in
the case of a post-crash external fire, special conditions are needed.
Specifically, the FAA proposes to require that the lower half of the
airplane fuselage, spanning the longitudinal area of the tank, be
resistant to fire penetration. ``Resistant to fire penetration'' would,
for this special condition, mean that this area provides fire
penetration resistance equivalent to the resistance which would be
provided if the fuselage were lined with thermal/acoustic insulation
that meets the flame penetration resistance test requirements of part
VII of Appendix F. The applicant's method of compliance may, but is not
required to, be based upon any inherent flame penetration resistance
capability
[[Page 19813]]
provided by the construction of the fuel tank and/or other surrounding
features.
The proposed 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 A321NeoXLR airplane. 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, these special
conditions would apply to that model as well.
Conclusion
This action affects only a certain novel or unusual design feature
on one model of airplane. It is not a rule of general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
The Federal Aviation Administration (FAA) proposes the following
special conditions as part of the type certification basis for Airbus
Model A321NeoXLR airplanes.
Passenger Protection From External Fire
The lower half of the fuselage, spanning the longitudinal location
of the rear center fuel tank, must be resistant to fire penetration.
Issued in Kansas City, Missouri, on April 1, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2022-07228 Filed 4-5-22; 8:45 am]
BILLING CODE 4910-13-P
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