[Federal Register Volume 60, Number 177 (Wednesday, September 13, 1995)]
[Rules and Regulations]
[Pages 47458-47464]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-22740]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-111; Special Conditions No. 25-ANM-106]


Special Conditions: Israel Aircraft Industries Model Galaxy 
Series Airplane, High Altitude Operation

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are 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.

EFFECTIVE DATE: October 13, 1995.

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:

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 aft-fuselage 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 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 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 

[[Page 47459]]
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 features, the special conditions would also apply to the 
other model under the provisions 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 use 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).
    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 pilot 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).

Discussion of Comments

    Notice of Proposed Special Conditions No. SC-95-4-NM for the Israel 
Aircraft Industries Model Galaxy Series Airplane, was published in the 
Federal Register on June 7, 1995 (60 FR 30019). No comments were 
received.

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 Special Conditions

    Accordingly, the following special conditions are issued as part of 
the type certification basis for the Israel Aircraft Industries, 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 

[[Page 47460]]
    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 operating 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 systems 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.

    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.

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    Issued in Renton, Washington, on August 31, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 95-22740 Filed 9-12-95; 8:45 am]
BILLING CODE 4910-13-C