[Federal Register: December 13, 2006 (Volume 71, Number 239)]
[Rules and Regulations]
[Page 74758-74761]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr13de06-2]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM313; Special Conditions No. 25-340-SC]
Special Conditions: Airbus Model A380-800 Airplane; Fire
Protection
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, which has novel and unusual design features, such as a full-
length, double deck passenger cabin and electrical equipment bays
distributed throughout the airplane. For these design features, the
applicable airworthiness regulations do not contain adequate or
appropriate safety standards regarding fire protection. 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 November 30, 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-
[[Page 74759]]
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 has 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 7, 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 Airbus Model A380-800 airplane has novel or unusual design
features relative to airplanes previously certificated under 14 CFR
part 25. These design features include full-length passenger cabins on
the main deck and the upper deck and electrical equipment bays that are
distributed throughout the airplane--on the main deck and upper deck as
well as in the lower lobe.
Generally, transport category airplanes have one or two electrical
equipment bays located in the lower lobe, adjacent to pressure
regulator/outflow valves. If there were a fire in an electrical
equipment bay, any smoke would be drawn toward the outflow valves and
be discharged from the airplane without entering occupied areas. In the
Airbus Model A380-800, the electrical equipment bays are distributed
throughout the airplane. Only those equipment bays located in the lower
lobe of the airplane are adjacent to pressure regulator/outflow valves.
For this combination of electrical equipment bays distributed
throughout the airplane and a double deck passenger cabin, the
applicable airworthiness regulations do not contain adequate or
appropriate safety standards regarding fire protection. Based upon its
review of incidents of smoke in the passenger cabin, the FAA determined
that an airplane with electrical equipment bays located below, on, and
above the main deck of a double deck airplane presents a greater risk
of smoke penetration than older designs with equipment bays only in the
lower lobe adjacent to pressure regulator/outflow valves.
In the event of a fire, airplanes with older designs rely upon
``trial and error'' to determine whether the source of fire or smoke is
in the electrical equipment bay. Typically, this involves the pilots
following a procedure in the Airplane Flight Manual. It may involve
shutting down power to the avionics equipment in one electrical
equipment bay and reconfiguring the airplane's environmental control
system (e.g., shutting down the recirculation fan) to see whether the
amount of smoke in the flightdeck or passenger compartment is reduced
or eliminated. If these actions do not eliminate the smoke, the flight
crew may turn the power back on in the one electrical equipment bay,
shut it off in the other equipment bay, and reconfigure the
environmental control system again to see whether the smoke is now
reduced or eliminated.
This approach may be acceptable for airplanes with no more than two
electrical equipment bays, both located in the lower lobe. In that
case, there are only two options: a fire in an electrical equipment bay
is in either one or the other. However, for an airplane with electrical
equipment bays located below, on, and above decks, this approach is not
sufficient, because--in the time it takes to determine the source of
smoke--a fire could spread and the quantity of smoke could increase
significantly.
Furthermore, the ``trial and error'' approach raises concern over
the lack of informational awareness that a flight crew would have
should smoke penetration occur. Many factors--including the airflow
pattern, configuration changes in the environmental control system,
potential leak paths, and location of outflow/ regulator valves--would
make it difficult to identify a smoke source, especially during flight
or system transients, such as climbing/descending or changes in
ventilation.
Current regulations (Sec. 25.857) require that cargo compartments
have a means to exclude hazardous quantities of smoke or fire
extinguishing agent from penetrating into occupied areas of the
airplane. However, there are no requirements that address the
following:
Preventing hazardous quantities of smoke or extinguishing
agent originating from the electrical equipment bays from penetrating
into occupied areas of the airplane;
Installing smoke or fire detectors in electrical equipment
bays; or
Preventing hazardous quantities of smoke or extinguishing
agent originating on one deck from spreading to the other deck.
The FAA believes that smoke detectors are needed in all electrical
equipment bays on the A380 to ensure that the flightcrew can make an
informed decision as to the source of smoke and can shut down the
specific electrical equipment bay from which the smoke is coming.
[[Page 74760]]
These special conditions, therefore, require that there be a smoke
or fire detection system in each electrical equipment bay. They also
include requirements to prevent propagation of hazardous quantities of
smoke or fire extinguishing agent between or throughout the passenger
cabins on the main deck and the upper deck.
Discussion of Comments
Notice of Proposed Special Conditions No. 25-05-08-SC, pertaining
to fire protection for the Airbus A380 airplane, was published in the
Federal Register on August 9, 2005 (70 FR 46108). A comment was
received from the Boeing Company.
Requested change 1: Boeing states that two conditions must be met
in order to issue Special Conditions and that neither one is met in
this case. Specifically, Boeing says that the distributed electrical
equipment bays are not a novel or unusual design feature, because
``There have been remote electrical equipment bays on many previously
certificated airplane models, and similar Special Conditions have not
been required.'' In addition, Boeing states that the current
regulations are adequate to ensure that remote electrical equipment
bays are safe. Boeing concludes, therefore, that the proposed Special
Conditions are neither necessary nor justified.
FAA response: The FAA does not agree. As stated above in the
Discussion of Novel or Unusual Design Features, the FAA finds that both
conditions required for issuance of a special condition are met:
previous part 25 rulemaking did not envision distributed electrical
equipment bays on passenger decks, and new standards are necessary to
maintain the level of safety of part 25. The FAA requested that Boeing
provide further corroboration of its comment that ``There have been
remote electrical equipment bays on many previously certificated
airplane models, and similar Special Conditions have not been
required.'' Our review of the information provided by Boeing indicates
that the specific design features incorporated into certain Boeing
models are not the same as those on the Airbus A380. Specifically, the
A380 has multiple electrical equipment bays distributed throughout the
lower lobe and on and above the main deck, whereas Boeing airplanes
have at most two electrical equipment bays, both located in the lower
lobe.
Historically, electrical equipment bays have been located in the
lower lobe, adjacent to pressure regulator/outflow valves such that any
smoke in the equipment bay would be drawn toward the outflow valves and
leave the airplane without entering occupied areas. The presence of
electrical equipment bays on and above the main deck presents a special
challenge in the event of a fire and creates uncertainty as to whether
smoke will penetrate into occupied areas of the airplane.
To summarize, the FAA believes that it is appropriate to impose
these special conditions for the A380-800 because:
(1) The A380-800 is a large, double deck airplane with multiple
electrical equipment bays distributed throughout, i.e., lower lobe,
main deck, and upper deck.
(2) The A380-800 has electrical equipment bays located above the
lower lobe and not adjacent to pressure regulator/outflow valves.
(3) The A380-800 has more than two electrical equipment bays.
(4) The A380-800 has electrical equipment bays located on or above
passenger decks or the flight deck.
(5) An airplane with this combination of electrical equipment bays
and passenger decks presents a greater risk of smoke penetration than
older designs with equipment bays only in the lower lobe, adjacent to
pressure regulator/outflow valves.
(6) For this combination of design features, the applicable
airworthiness regulations do not contain adequate or appropriate safety
standards regarding fire protection.
(7) All electrical equipment bays on the A380 should contain smoke
or fire detectors to ensure that in the event of a fire in one
equipment bay the flight crew has sufficient situational information to
enable them to shut down the correct electrical equipment bay.
Requested change 2: Boeing objects to applying the proposed Special
Conditions ``to all [electrical] equipment bays, not just the remote
equipment bay(s) that the FAA has determined to be novel and
inadequately covered by the existing regulations. Applying this Special
Condition to the main equipment bay appears to be a form of general
rulemaking via Special Condition.''
FAA response: The FAA does not agree. We contacted the Boeing
Company regarding its comment and asked for clarification. It appears
that Boeing's comment was focused on multiple electrical equipment bays
located in the lower lobe and not the distributed electrical equipment
bays in the A380 design. However, it is not only the remote electrical
equipment bays which are a novel or unusual design feature. It is the
combination of electrical equipment bays distributed on the main deck,
the upper deck, and the lower lobe along with full-length passenger
cabins on the main deck and the upper deck. This combination raises the
possibility that smoke from a fire in an electrical equipment bay will
penetrate into the flightdeck or into one or both passenger cabins. As
noted above, the presence of smoke detectors in these equipment bays
will ensure that the flight crew has sufficient situational information
to enable them to shut down the correct electrical equipment bay and to
prevent hazardous quantities of smoke from entering the flight deck or
passenger cabins.
Based on the fact that the electrical distribution center on the
A380 includes electrical equipment bays in locations where fire and
smoke are more hazardous to passengers, we believe that this special
condition should apply not only to electrical equipment bays on the
passenger decks, but to all electrical equipment bays. To do otherwise
would not protect the entire electrical distribution system when such
protection could be accomplished readily.
Requested change 3: Finally, Boeing comments that the proposed
Special Conditions add requirements for detecting smoke and fire and
for preventing penetration of smoke and that such requirements have
previously been associated with fire protection for cargo compartments,
but not for electrical equipment bays. According to the commenter,
There have been many issues raised with the smoke quantities and
test methods for these tests, especially for cargo compartment
tests. None of these discussions have included equipment bays as the
location of the test, or the materials in the equipment bay as the
fuel of the fire. Therefore, there is no agreement as to the
detailed test procedures for the proposed equipment bay detection
tests.
FAA response: This comment pertains to how Airbus will show
compliance with the requirements to install a smoke or fire detection
system in each electrical equipment bay and to prevent smoke
originating from the electrical equipment bays from penetrating between
or throughout passenger cabins on the main deck and the upper deck. We
have discussed these issues with Airbus and with specialists within the
European Aviation Safety Agency and have established appropriate test
criteria through the issue paper process.
Clarification
The FAA has revised the text in the Discussion of Novel or Unusual
Design Features to clarify that the special conditions apply to
propagation of
[[Page 74761]]
smoke or extinguishing agents between or throughout the main deck and
upper deck passenger cabins. Similarly, we have revised the text of
Special Condition a.2.(c) to clarify that smoke from a source below the
main deck must not rise above armrest height on the main deck.
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. Requirements to prevent propagation of smoke or extinguishing
agents between or throughout main deck and upper deck passenger cabins:
1. To prevent such propagation, the following must be demonstrated:
(a) Means to prevent hazardous quantities of smoke or extinguishing
agent originating from the electrical equipment bays from
incapacitating passengers and crew, and
(b) Means to prevent hazardous quantities of smoke or extinguishing
agent originating from one deck from propagating to the other deck via
vents, stairways, and joints in the floor/ceiling.
2. A ``small quantity'' of smoke may enter an occupied area only
under the following conditions:
(a) The smoke enters occupied areas during system transients \1\
from below deck sources. No sustained smoke penetration beyond that
from environmental control system transients is permitted.
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\1\ Transient airflow conditions may cause air pressure
differences between compartments, before the ventilation and
pressurization system is reconfigured. Additional transients occur
during changes to system configurations such as pack shut-down, fan
shut-down, or changes in cabin altitude; transition in bleed source
change, such as from intermediate stage to high stage bleed air; and
cabin pressurization ``fly-through'' during descent may reduce air
conditioning inflow. Similarly, in the event of a fire, a small
quantity of smoke that penetrates into an occupied area before the
ventilation system is reconfigured would be acceptable under certain
conditions described within this special condition.
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(b) Penetration of the small quantity of smoke is a dynamic event,
involving either dissipation or mobility. Dissipation is rapid dilution
of the smoke by ventilation air, and mobility is rapid movement of the
smoke into and out of the occupied area. In no case, should there be
formation of a light haze indicative of stagnant airflow, as this would
indicate that the ventilation system is failing to meet the
requirements of Sec. 25.831(b).
(c) The smoke from a smoke source below the main deck must not rise
above armrest height on the main deck.
(d) The smoke from a source on the same deck or above the deck must
dissipate rapidly via dilution with fresh air and be evacuated from the
airplane. A procedure must be included in the Airplane Flight Manual to
evacuate smoke from the occupied areas of the airplane. In order to
demonstrate that the quantity of smoke is small, a flight test must be
conducted which simulates the emergency procedures used in the event of
a fire during flight, including the use of Vmo/
Mmo descent profiles and a simulated landing, if such
conditions are specified in the emergency procedure.
b. Requirement for fire detection in electrical equipment bays:
A smoke or fire detection system that complies with 14 CFR
25.858(c) and (d) must be provided for each electrical equipment bay.
Each system must provide a visual indication to the flight deck within
one minute after the start of a fire in an electrical equipment bay.
Airplane tests must be conducted to show compliance with this
requirement, and the performance of the smoke or fire detection system
must be shown, in accordance with Advisory Circular 25-9A or by other
means acceptable to the FAA.
Issued in Renton, Washington, on November 30, 2006.
Kevin Mullin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E6-21191 Filed 12-12-06; 8:45 am]
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