[Federal Register: September 11, 2006 (Volume 71, Number 175)]
[Rules and Regulations]
[Page 53316-53318]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11se06-7]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM320; Special Conditions No. 25-330-SC]
Special Conditions: Airbus Model A380-800 Airplane, Escape
Systems Inflation Systems
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for the Airbus A380-800
airplane. This airplane will have novel or unusual design features when
compared to the state of technology envisioned in the airworthiness
standards for transport category airplanes. Many of these novel or
[[Page 53317]]
unusual design features are associated with the complex systems and the
configuration of the airplane, including its full-length double deck.
For these design features, the applicable airworthiness regulations do
not contain adequate or appropriate safety standards regarding escape
system reliability. 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. Additional special conditions will be
issued for other novel or unusual design features of the Airbus Model
A380-800 airplane.
DATES: Effective Date: The effective date of these special conditions
is August 28, 2006.
FOR FURTHER INFORMATION CONTACT: Holly Thorson, FAA, International
Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;
telephone (425) 227-1357; facsimile (425) 227-1149.
SUPPLEMENTARY INFORMATION:
Background
Airbus applied for FAA certification/validation of the
provisionally-designated Model A3XX-100 in its letter AI/L 810.0223/98,
dated August 12, 1998, to the FAA. Application for certification by the
Joint Aviation Authorities (JAA) of Europe had been made on January 16,
1998, reference AI/L 810.0019/98. In its letter to the FAA, Airbus
requested an extension to the 5-year period for type certification in
accordance with 14 CFR 21.17(c).
The request was for an extension to a 7-year period, using the date
of the initial application letter to the JAA as the reference date. The
reason given by Airbus for the request for extension is related to the
technical challenges, complexity, and the number of new and novel
features on the airplane. On November 12, 1998, the Manager, Aircraft
Engineering Division, AIR-100, granted Airbus' request for the 7-year
period, based on the date of application to the JAA.
In its letter AI/LE-A 828.0040/99 Issue 3, dated July 20, 2001,
Airbus stated that its target date for type certification of the Model
A380-800 had been moved from May 2005, to January 2006, to match the
delivery date of the first production airplane. In a subsequent letter
(AI/L 810.0223/98 issue 3, dated January 27, 2006), Airbus stated that
its target date for type certification is October 2, 2006. In
accordance with 14 CFR 21.17(d)(2), Airbus chose a new application date
of December 20, 1999, and requested that the 7-year certification
period which had already been approved be continued. The FAA has
reviewed the part 25 certification basis for the Model A380-800
airplane, and no changes are required based on the new application
date.
The Model A380-800 airplane will be an all-new, four-engine jet
transport airplane with a full double-deck, two-aisle cabin. The
maximum takeoff weight will be 1.235 million pounds with a typical
three-class layout of 555 passengers.
Type Certification Basis
Under the provisions of 14 CFR 21.17, Airbus must show that the
Model A380-800 airplane meets the applicable provisions of 14 CFR part
25, as amended by Amendments 25-1 through 25-98. If the Administrator
finds that the applicable airworthiness regulations do not contain
adequate or appropriate safety standards for the Airbus A380-800
airplane because of novel or unusual design features, special
conditions are prescribed under the provisions of 14 CFR 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Airbus Model A380-800 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. In addition, the
FAA must issue a finding of regulatory adequacy pursuant to section 611
of Public Law 93-574, the ``Noise Control Act of 1972.''
Special conditions, as defined in 14 CFR 11.19, are issued in
accordance with 14 CFR 11.38 and become part of the type certification
basis in accordance with 14 CFR 21.17(a)(2).
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 the provisions of 14 CFR 21.101.
Discussion of Novel or Unusual Design Features
The inflation system for the escape systems associated with the
exits includes a pressurized cylinder with a mixture of carbon dioxide
and argon in both gaseous and liquid states. The inflation system also
includes a smaller cylinder containing a solid propellant that burns to
generate gaseous propellant. The opening of the valve and the ignition
of the propellant are accomplished by the firing of squibs. The firing
of these squibs is sequenced to improve their performance in the
extreme temperatures to which they are subjected. Firing of the squibs
is controlled by a system mounted on the emergency exit.
The proposed design for the escape systems on the A380 is much more
complex than the design of systems currently in use. Typically,
inflation systems for escape systems consist of a pressurized cylinder
containing a mixture of gases and a regulator valve that reduces the
outlet pressure supplied from the inflation cylinder. The regulator
valve is opened either by mechanical means or by the firing of a squib.
The regulations governing the certification of the A380 do not
adequately address the certification requirements of this type of
inflation system for an escape system. Furthermore, the Technical
Standard Order (TSO) that addresses escape systems (i.e., TSO-C69c)
does not adequately address this type of inflation system. The current
requirements for escape system reliability are predicated on a simple
inflation system, where reliability is driven by the performance of the
inflatable itself. The existing requirements do not account for an
inflation system that could adversely affect the overall reliability of
the escape system.
[[Page 53318]]
Since the A380 has 16 emergency exits, the requirements of Sec.
25.810 require a total of 80 successful deployments (5 successive
deployments for each exit). However, since the requirements apply to
each system independently, failures in a system common to all the
escape systems would not be adequately addressed. Therefore, the
inflation system needs a specific requirement that will show adequate
system reliability. With a goal of achieving 95% reliability of the
inflation system with a 95% confidence, we are establishing such a
requirement. As we noted above, the propellant used is designed to
burn. The regulations do not address this type of propellant, and some
measure of fire safety protection is needed. United Nations document
No. ST/SG/AC.10/I1/Rev.3 ``Transport of Dangerous Goods, Manual of
Tests and Criteria,'' section 13.7.1, contains a small scale test that
addresses this concern. Propellants that pass this test will not be a
fire hazard.
Therefore, a special condition is needed to ensure that the
inflation system for the A380 escape system is reliable and that the
propellant itself does not constitute a fire hazard.
Discussion of Comments
Notice of Proposed Special Conditions No. 25-05-15-SC, pertaining
to escape systems inflation systems, was published in the Federal
Register on August 9, 2005, (70 FR 46100). Comments were received from
the Airline Pilots Association (ALPA) and an individual commenter.
Requested change 1: ALPA recommends that the tests of the inflation
system ``be conducted on the aircraft (or a mockup). Bench testing does
not adequately ensure that the entire system will have the declared
reliability. The system and its components should be subjected to
accelerated aging representative of long-term storage (temperature and
pressure cycling), long term exposure (high and low frequency
vibration) as part of each test.'' ALPA adds that ``the inflation
systems should be demonstrated to function in winds from the most
severe angle at speeds up to at least the maximum wind speed (gust
included) for which flight operations can occur.''
FAA response: Many of these recommendations go beyond current
regulatory requirements for inflation systems. For example, wind
performance is already specified in 14 CFR part 25. The purpose of the
special conditions is to establish criteria that will validate that the
reliability of the inflation system as a component will not drive the
overall reliability of the escape system. Thus tests on the escape
slides installed on the airplane will be performed as is consistent
with current practice, and additional tests will be performed on the
inflation system itself. Accordingly, we have not changed the special
conditions, as proposed.
Requested change 2: An individual commenter expresses concern about
various aspects of the inflation system, including its output of high
temperature gas; residue from combustion of the solid propellant; high
pressure produced in the inflation system; activation of the inflation
system, including inadvertent activation by a lightning strike; and the
need for a redundant manual (backup) power source for the inflation
system.
FAA response: These comments relate to the general safety and
suitability of the inflation system for the escape system and its
related components. These are fundamental considerations for any
airplane system. Although the inflation system may warrant highly
specific considerations, it is the need to show the reliability of the
system relative to conventional design that makes it novel. Showing
that the system elements are compatible with one another is a basic
certification requirement for any system.
To address the novel features of the inflation system requires
imposition of special conditions in addition to the applicable
requirements of Sec. 25.1301. The slide must be both soaked and
inflated at a range of temperatures to determine its operating range.
The minimum pressures are determined to establish evacuation rate and
stiffness. Therefore, the initial internal pressure of the slide will
not be an issue in the qualification. The electrical systems are
protected against lightning by other requirements. The manual backup
is, indeed, an alternative electrical supply, which is addressed in the
system safety analysis. Accordingly, we have not changed the special
conditions, as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Airbus A380-800 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 features, these special conditions
would apply to that model as well under the provisions of Sec. 21.101.
Conclusion
This action affects only certain novel or unusual design features
of the Airbus A380-800 airplane. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
0
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 the Airbus A380-800 airplane.
a. In addition to the requirements of Sec. 25.810, the following
special condition applies:
To ensure that the inflation system is a reliable design, it must
be tested using 84 inflation/firing system bench tests with no more
than one failure. For these special conditions, the inflation/firing
system is defined as everything upstream of the outlet connection to
the inflation valve, which includes but is not limited to the door-
mounted systems that provide the firing signals to the squibs, the
squibs themselves, the solid propellant, and the valve.
b. In addition to the requirements of Sec. 25.853(a) and Appendix
F Part I (a)(ii), in standard atmosphere conditions, the following
special condition applies:
To ensure that the propellant itself does not contribute
significantly to a fire, the propellant must be subjected to and must
pass a standard ``Small-Scale Burning Test,'' as specified in United
Nations document No. ST/SG/AC.10/11/Rev. 3 ``Transport of Dangerous
Goods, Manual of Tests and Criteria,'' section 13.7.1.
Issued in Renton, Washington, on August 28, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E6-15010 Filed 9-8-06; 8:45 am]
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