[Federal Register Volume 60, Number 124 (Wednesday, June 28, 1995)]
[Proposed Rules]
[Pages 33366-33372]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-15890]



 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 60, No. 124 / Wednesday, June 28, 1995 / 
Proposed Rules  

[[Page 33366]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-112; Notice No. SC-95-5-NM]


Special Condition: Gulfstream Aerospace Corporation, Model 
Gulfstream V, High Altitude Operations

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: The document proposes special conditions for the Gulfstream 
Model Gulfstream V airplane. This new airplane will be capable of 
operating at a maximum altitude of 51,000 feet. The applicable 
regulations do not contain adequate or appropriate safety standards for 
the protection of the fuselage structure or passengers and crew from 
the effects of high altitude operations. 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: Comments must be received on or before August 14, 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-112, 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-112. 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:
Robert L. Salas, FAA, Standardization Branch, ANM-113, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, Washington 98055-4056.

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 or notice 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 
before further rulemaking action is taken on these proposals. The 
proposals contained in this notice may be changed in light of 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 notice must submit with those 
comments a self-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket No. NM-112.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On February 26, 1992, Gulfstream Aerospace Corporation, P.O. Box 
2206, Savannah, GA 31402-2206, applied for an amended type certificate 
in the transport airplane category for the Model Gulfstream V airplane. 
The Gulfstream V is a T-tail, low swept wing, business jet airplane 
powered by two Rolls-Royce BR710-48 turbofan engines mounted on pylons 
extending from the aft fuselage. Each engine will be capable of 
delivering 14,750 pounds thrust. The flight controls will be powered 
and capable of manual reversion. The airplane has a seating capacity of 
up to nineteen passengers, and a maximum takeoff weight of 89,000 
pounds. Gulfstream has requested certification for operations up to 
51,000 feet.

Type Certification Basis

    Under the provisions of Sec. 21.101 of the FAR, Gulfstream must 
show, except as provided in Sec. 25.2, that the Model Gulfstream V 
meets the applicable provisions of part 25, effective February 1, 1965, 
as amended by Amendments 25-1 through 25-75. In addition, the proposed 
certification basis for the Model Gulfstream V 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 
Amendment 36-1 through the amendment in effect at the time of 
certification. No exemptions are anticipated. The special conditions 
that may be developed as a result of this notice will 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 proposed 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 Gulfstream V 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. 21.101(b)(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, or should any other model already included on 
the same type certificate be modified to incorporate 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 Features

    The Model Gulfstream V will be certificated for operations at a 
maximum altitude of 51,000 feet. This unusually high operating altitude 
constitutes a novel or unusual design feature for which the applicable 
airworthiness [[Page 33367]] regulations do not contain adequate or 
appropriate safety standards.
    There are no specific regulations that address protection 
requirements for the airplane fuselage pressure vessel or passengers 
and crew, in the event of a rapid decompression, during high altitude 
operations. The potential adverse impact from rapid decompression at 
high altitudes have made it necessary to provide adequate protection.
    To ensure that a level of safety is achieved equivalent to that 
intended by the regulations incorporated by reference, special 
conditions are proposed for the Gulfstream V which would require 
compliance with additional requirements to provide protection from the 
direct and indirect effects of high altitude operations.
    Damage tolerance methods are proposed to be used to ensure pressure 
vessel integrity while operating at the higher altitudes. Crack growth 
data are used to prescribe an inspection program which will detect 
cracks before an opening in the pressure vessel would allow rapid 
decompression. Initial crack sizes for detection are determined under 
Sec. 25.571, Amendment 25-72. The cabin altitude after failure may not 
exceed the limits specified in Figures 3 and 4.
    In order to ensure that there is adequate fresh air to 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 would 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 24,000 feet, 
reverse diffusion leads to low oxygen partial pressure 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. To prevent permanent physiological damage, the cabin altitude 
must not exceed 25,000 feet for more than two minutes. The maximum peak 
cabin altitude of 40,000 feet is consistent with the standards 
established for previous certification programs. In addition, at these 
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 above 27,000 feet can result in cabin altitudes that 
approach 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 receives 
oxygen will provide a safety margin against being incapacitated and can 
be accomplished by the use of mask-mounted regulators. The proposed 
special condition therefore requires 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 proposed special conditions and for improbable failures not covered 
by the special conditions, provided the cabin altitude is limited.
    As discussed above, the proposed special conditions would be 
applicable initially to the Model Gulfstream V. Should Gulfstream apply 
at a later date for a change to the type of certificate to include 
another model incorporating the same novel or unusual design feature, 
the special conditions would apply to that model as well, under the 
provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects certain design features only on the Gulfstream 
V 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 proposed 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 Condition

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Gulfstream Model Gulfstream V series airplanes.

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 
assure that cracks and normal fuselage leak rates will not deteriorate 
to the extent that an unsafe condition could exist during normal 
operation.
    (c) With regard to the fuselage structural design for cabin 
pressure capability above 45,000 feet altitude, the pressure vessel 
structure, including doors and windows, must comply with 
Sec. 25,365(d), using a factor of 1.67 instead of the 1.33 factor 
described.
    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 to any system which could adversely 
affect the cabin ventilating air. For normal operations, crew members 
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 lieu of 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 FAR 25.841, 
the following apply: [[Page 33368]] 
    (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 d.1. and d.2. 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.
    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 donnning 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 June 15, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 95-15890 Filed 6-27-95; 8:45 am]
BILLING CODE 4910-13-M