[Federal Register Volume 60, Number 109 (Wednesday, June 7, 1995)]
[Proposed Rules]
[Pages 30019-30026]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-13940]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-111; Notice No. SC-95-4-NM]
Special Conditions: Israel Aircraft Industries Model Galaxy
Series Airplane, High Altitude Operation
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for the Israel
Aircraft Industries (IAI) Ltd. Model Galaxy airplane. This new airplane
will have an unusual design feature associated with an unusually high
operating altitude (45,000 feet), for which the applicable
airworthiness regulations do not contain adequate or appropriate safety
standards. 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: Comments must be received on or before July 24, 1995.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Office of the Assistant Chief Counsel,
Attn.: Rules Docket (ANM-7), Docket No. NM-111, 1601 Lind Avenue SW.,
Renton, Washington, 98055-4056; or delivered in duplicate to the Office
of the Assistant Chief Counsel at the above address. Comments must be
marked ``Docket No. NM-111.'' Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4:00
p.m.
FOR FURTHER INFORMATION CONTACT:
Timothy Dulin, FAA, Standardization Branch, ANM-113, Transport Airplane
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW.,
Renton, Washington, 98055-4056, telephone (206) 227-2141.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of
these proposed special conditions by submitting such written data,
views, or arguments as they may desire. Communications should identify
the regulatory docket and special conditions number and be submitted in
duplicate to the address specified above. All communications received
on or before the closing date for comments will be considered by the
Administrator. These special conditions may be changed in light of the
comments received. All comments submitted will be available in the
Rules Docket for examination by interested persons, both before and
after the closing date for comments. A report summarizing each
substantive public contact with FAA personnel concerning this
rulemaking will be filed in the docket. Persons wishing the FAA to
acknowledge receipt of their comments submitted in response to this
request must submit with those comments a self-addressed, stamped
postcard on which the following statement is made: ``Comments to Docket
No. NM-111.'' The postcard will be date stamped and returned to the
commenter.
Background
On July 29, 1992, IAI Ltd., Ben-Gurion International Airport,
70100, Israel, applied for a new type certificate in the transport
airplane category for the Model Galaxy airplane. The IAI Model Galaxy
airplane is a derivative of the IAI Model 1125 Westwind Astra and is
designed to be a long range, high speed swept low wing airplane with
two aftfuselage mounted Pratt & Whitney PW 306A engines and a
conventional empennage.
The type design of the Model Galaxy contains a number of novel and
unusual design features for an airplane type certificated under the
applicable provisions of part 25 of the Federal Aviation Regulations
(FAR). Those features include the relatively small passenger cabin
volume and a high maximum operating altitude. The applicable
airworthiness requirements do not contain adequate or appropriate
safety standards for the IAI Galaxy; therefore, special conditions are
necessary to establish a level of safety [[Page 30020]] equivalent to
that established in the regulations.
Type Certification Basis
Under the provisions of Sec. 21.17 of the FAR, IAI Ltd. must show
that the Galaxy meets the applicable provisions of part 25, effective
February 1, 1965, as amended by Amendments 25-1 through 25-77. The
certification basis may also include later amendments to part 25 that
are not relevant to these special conditions. In addition, the
certification basis for the Galaxy includes part 34, effective
September 10, 1990, plus any amendments in effect at the time of
certification; and part 36, effective December 1, 1969, as amended by
Amendments 36-1 through the amendment in effect at the time of
certification. These special conditions form an additional part of the
type certification basis. In addition, the certification basis may
include other special conditions that are not relevant to these special
conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 25, as amended) do not contain adequate or
appropriate safety standards for the Galaxy because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16 to establish a level of safety equivalent to
that established in the regulations.
Special conditions, as appropriate, are issued in accordance with
Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28
and 11.29, and become part of the type certification basis in
accordance with Sec. 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 Sec. 21.101(a)(1).
Novel or Unusual Design Feature
The IAI Galaxy will incorporate an unusual design feature in that
it will be certified to operate up to an altitude of 45,000 feet.
The FAA considers certification of transport category airplanes for
operation at altitudes greater than 41,000 feet to be a novel or
unusual feature because current part 25 does not contain standards to
ensure the same level of safety as that provided during operation at
lower altitudes. Special conditions have therefore been adopted to
provide adequate standards for transport category airplanes previously
approved for operation at these high altitudes, including certain
Learjet models, the Boeing Model 747, Dassault-Breguet Falcon 900,
Canadair Model 600, Cessna Model 650, Israel Aircraft Industries Model
1125 Westwind Astra, and Cessna Model 560. The special conditions for
the Learjet Model 45 are considered the most applicable to the Galaxy
and its proposed operation and are therefore used as the basis for the
special conditions described below.
Damage tolerance methods are proposed to be used to ensure pressure
vessel integrity while operating at the higher altitudes, in lieu of
the \1/2\-bay crack criterion used in some previous special conditions.
Crack growth data are used to prescribe an inspection program that
should detect cracks before an opening in the pressure vessel would
allow rapid depressurization. Initial crack sizes for detection are
determined under Sec. 25.571, as amended by Amendment 25-72. The
maximum extent of failure and pressure vessel opening determined from
the above analysis must be demonstrated to comply with the
pressurization section of the proposed special conditions, which state
that the cabin altitude after failure must not exceed the cabin
altitude/time curve limits shown in Figures 3 and 4.
In order to ensure that there is adequate fresh air for crewmembers
to perform their duties, to provide reasonable passenger comfort, and
to enable occupants to better withstand the effects of decompression at
high altitudes, the ventilation system must be designed to provide 10
cubic feet of fresh air per minute per person during normal operations.
Therefore, these special conditions require that crewmembers and
passengers be provided with 10 cubic feet of fresh air per minute per
person. In addition, during the development of the supersonic transport
special conditions, it was noted that certain pressurization failures
resulted in hot ram or bleed air being used to maintain pressurization.
Such a measure can lead to cabin temperatures that exceed human
tolerance. Therefore, these special conditions require airplane
interior temperature limits following probable and improbable failures.
Continuous flow passenger oxygen equipment is certificated for use
up to 40,000 feet; however, for rapid decompressions above 34,000 feet,
reverse diffusion leads to low oxygen partial pressures in the lungs,
to the extent that a small percentage of passengers may lose useful
consciousness at 35,000 feet. The percentage increases to an estimated
60 percent at 40,000 feet, even with the use of the continuous flow
system. Therefore, to prevent permanent physiological damage, the cabin
altitude must not exceed 25,000 feet for more than 2 minutes, or 40,000
feet for any time period. The maximum peak cabin altitude of 40,000
feet is consistent with the standards established for previous
certification programs. In addition, at high altitudes the other
aspects of decompression sickness have a significant, detrimental
effect on pilot performance (for example, a pilot can be incapacitated
by internal expanding gases).
[[Page 30021]] Decompression resulting in cabin altitudes above the
37,000-foot limit depicted in Figure 4 approaches the physiological
limits of the average person; therefore, every effort must be made to
provide the pilots with adequate oxygen equipment to withstand these
severe decompressions. Reducing the time interval between
pressurization failure and the time the pilots receive oxygen will
provide a safety margin against being incapacitated and can be
accomplished by the use of mask-mounted regulators. These special
conditions therefore require pressure demand masks with mask-mounted
regulators for the flightcrew. This combination of equipment will
provide the best practical protection for the failures covered by the
special conditions and for improbable failures not covered by the
special conditions, provided the cabin altitude is limited.
As discussed above, these special conditions are applicable to the
IAI Model Galaxy. Should IAI Ltd. 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 under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain design features on the IAI Ltd.
Model Galaxy airplane. It is not a rule of general applicability and
affects only the manufacturer who applied to the FAA for approval of
these features on the airplane.
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. app. 1344, 1348(c), 1352, 1354(a), 1355,
1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et
seq.; E.O. 11514; and 49 U.S.C. 106(g).
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the IAI Ltd. Model Galaxy series airplanes:
Operation to 45,000 Feet
1. Pressure Vessel Integrity.
(a) The maximum extent of failure and pressure vessel opening that
can be demonstrated to comply with paragraph 4 (Pressurization) of this
special condition must be determined. It must be demonstrated by crack
propagation and damage tolerance analysis supported by testing that a
larger opening or a more severe failure than demonstrated will not
occur in normal operations.
(b) Inspection schedules and procedures must be established to
ensure that cracks and normal fuselage leak rates will not deteriorate
to the extent that an unsafe condition could exist during normal
operation.
2. Ventilation. In lieu of the requirements of Sec. 25.831(a), the
ventilation system must be designed to provide a sufficient amount of
uncontaminated air to enable the crewmembers to perform their duties
without undue discomfort or fatigue, and to provide reasonable
passenger comfort during normal operation conditions and also in the
event of any probable failure of any system that could adversely affect
the cabin ventilating air. For normal operations, crewmembers and
passengers must be provided with at least 10 cubic feet of fresh air
per minute per person, or the equivalent in filtered, recirculated air
based on the volume and composition at the corresponding cabin pressure
altitude of not more than 8,000 feet.
3. Air Conditioning. In addition to the requirements of
Sec. 25.831, paragraphs (b) through (e), the cabin cooling system must
be designed to meet the following conditions during flight above 15,000
feet mean sea level (MSL):
(a) After any probable failure, the cabin temperature-time history
may not exceed the values shown in Figure 1.
(b) After any improbable failure, the cabin temperature-time
history may not exceed the values shown in Figure 2.
4. Pressurization. In addition to the requirements of Sec. 25.841,
the following apply:
(a) The pressurization system, which includes for this purpose
bleed air, air conditioning, and pressure control systems, must prevent
the cabin altitude from exceeding the cabin altitude-time history shown
in Figure 3 after each of the following:
(1) Any probable malfunction or failure of the pressurization
system. The existence of undetected, latent malfunctions or failures in
conjunction with probable failures must be considered.
(2) Any single failure in the pressurization system, combined with
the occurrence of a leak produced by a complete loss of a door seal
element, or a fuselage leak through an opening having an effective area
2.0 times the effective area that produces the maximum permissible
fuselage leak rate approved for normal operation, whichever produces a
more severe leak.
(b) The cabin altitude-time history may not exceed that shown in
Figure 4 after each of the following:
(1) The maximum pressure vessel opening resulting from an initially
detectable crack propagating for a period encompassing four normal
inspection intervals. Mid-panel cracks and cracks through skin-stringer
and skin-frame combinations must be considered.
(2) The pressure vessel opening or duct failure resulting from
probable damage (failure effect) while under maximum operating cabin
pressure differential due to a tire burst, engine rotor burst, loss of
antennas or stall warning vanes, or any probable equipment failure
(bleed air, pressure control, air conditioning, electrical source(s),
etc.) that affects pressurization.
(3) Complete loss of thrust from all engines.
(c) In showing compliance with paragraphs 4(a) and 4(b) of these
special conditions (Pressurization), it may be assumed that an
emergency descent is made by approved emergency procedure. A 17-second
crew recognition and reaction time must be applied between cabin
altitude warning and the initiation of an emergency descent.
Note: For the flight evaluation of the rapid descent, the test
article must have the cabin volume representative of what is
expected to be normal, such that IAI Ltd. must reduce the total
cabin volume by that which would be occupied by the furnishings and
total number of people.
[[Page 30022]] 5. Oxygen Equipment and Supply.
(a) A continuous flow oxygen system must be provided for the
passengers.
(b) A quick-donning pressure demand mask with mask-mounted
regulator must be provided for each pilot. Quick-donning from the
stowed position must be demonstrated to show that the mask can be
withdrawn from stowage and donned within 5 seconds.
BILLING CODE 4910-13-M
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BILLING CODE 4910-13-C
Issued in Renton, Washington, on May 26, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 95-13940 Filed 6-6-95; 8:45 am]
BILLING CODE 4910-13-M
