[Federal Register Volume 60, Number 200 (Tuesday, October 17, 1995)]
[Rules and Regulations]
[Pages 53691-53697]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-25676]
========================================================================
Rules and Regulations
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains regulatory documents
having general applicability and legal effect, most of which are keyed
to and codified in the Code of Federal Regulations, which is published
under 50 titles pursuant to 44 U.S.C. 1510.
The Code of Federal Regulations is sold by the Superintendent of Documents.
Prices of new books are listed in the first FEDERAL REGISTER issue of each
week.
========================================================================
Federal Register / Vol. 60, No. 200 / Tuesday, October 17, 1995 /
Rules and Regulations
[[Page 53691]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-112; Special Conditions No. 25-ANM-108]
Special Condition: Gulfstream Aerospace Corporation, Model
Gulfstream V, High Altitude Operations
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are 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 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: November 16, 1995.
FOR FURTHER INFORMATION CONTACT:
Gerald Lakin, FAA, Standardization Branch, ANM-113, Transport Airplane
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW.,
Renton, Washington, 98055-4056, (206) 227-1187.
SUPPLEMENTARY INFORMATION:
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 BMW Rolls-Royce BR700-710A1-10 turbofan engines mounted
on pylons extending from the aft fuselage. Each engine will be capable
of delivering 14,750 pounds thrust. The 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, 1995,
as amended by Amendments 25-1 through 25-81. 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; part 36, effective December 1, 1969, as amended by
Amendment 36-1 through the amendment in effect at the time of
certification; and certain exceptions and special conditions that are
not relevant to these special conditions. No exemptions are
anticipated. These special conditions form an additional part of the
type certification basis.
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 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 has 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, these special
conditions 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 grown
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 require airplane
interior
[[Page 53692]]
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 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 37,000 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. 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
proposed 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
initially to the Model Gulfstream V. Should Gulfstream 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. ANM-95-5-NM for the
Gulfstream Aerospace Corporation, Model Gulfstream V, was published in
the Federal Register on June 28, 1995 (60 FR 33366). One commenter, the
applicant, submitted four comments as follows:
(1) The commenter states that the current nomenclature for the
turbofan engine is BMW Rolls-Royce BR700-710A1-10 in lieu of Rolls-
Royce BR710-48. The FAA agrees with the commenter and has incorporated
the change in this document.
(2) The commenter states that the presently accepted Certification
Basis for the Gulfstream V is part 25, effective February 1, 1965, as
amended by Amendments 25-1 through 25-81 in lieu of Amendment 25-75.
The FAA agrees with the commenter and has incorporated the change in
this document.
(3) The commenter asks the question whether certain wording
discrepancies under the ``Novel or Unusual Design Features'' portion of
the notice are typographical errors or if there has been a change in
philosophy. The wording has to do with the value of ``rapid
decompressions above 24,000 feet,'' and ``decompression above 27,000
feet.'' In numerous preceding publications over the years of such high
altitude special conditions, these altitudes have been stated as 34,000
and 37,000 feet respectively. The FAA confirms that these discrepancies
are typographical errors made by the Federal Register when they
published the notice. The correct values are 34,000 feet and 37,000
feet respectively, and those values are reflected in this document.
(4) The commenter asks the question whether a change in Figure 3,
Cabin Altitude Vs Time, is an error or a change in philosophy/
requirements. The question has to do with the fact that the horizontal
portion of the 25,000 foot altitude line begins to break downward at
the 6 minute point of the figure. In numerous preceding publications
over the years of such high altitude special conditions, this break
point in the graph has been at 7 minutes. The FAA confirms that the 6
minute break point is in error and the 7 minute break value is correct.
Figure 3 is corrected in this document to reflect the 7 minute break
value point.
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, Federal Aviation Administration,
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 Special Conditions
Accordingly, the following special conditions are issued as part of
the type certification basis for the Gulfstream Aerospace Corporation,
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).
[[Page 53693]]
(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:
(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 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
[[Page 53694]]
[GRAPHIC][TIFF OMITTED]TR17OC95.000
[[Page 53695]]
[GRAPHIC][TIFF OMITTED]TR17OC95.001
[[Page 53696]]
[GRAPHIC][TIFF OMITTED]TR17OC95.002
[[Page 53697]]
[GRAPHIC][TIFF OMITTED]TR17OC95.003
BILLING CODE 4910-13-C
Issued in Renton, Washington, on October 5, 1995.
Gary L. Killion,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 95-25676 Filed 10-16-95; 8:45 am]
BILLING CODE 4910-13-M
