[Federal Register Volume 64, Number 176 (Monday, September 13, 1999)]
[Proposed Rules]
[Pages 49413-49418]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-23719]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE154; Notice No. 23-99-01-SC]
Special Conditions: Cessna Aircraft Company, Model 525A, High
Altitude Operation.
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for the Cessna
Aircraft Company Model 525A airplane. This airplane will have novel or
unusual design features associated with high altitude operation. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. 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 October 13, 1999.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Regional Counsel, ACE-7, Attention:
Rules Docket, Docket No. CE154, 601 East 12th Street, Kansas City,
Missouri 64106, or delivered in duplicate to the Regional Counsel at
the above address.
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Comments must be marked: CE154. Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Lowell Foster, Federal Aviation
Administration, Aircraft Certification Service, Small Airplane
Directorate, ACE-111, 601 East 12th Street, Kansas City, Missouri, 816-
426-5688, fax 816-426-2169.
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.
The proposals described in this notice may be changed in light of the
comments received. All comments received 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 include with those
comments a self-addressed, stamped postcard on which the following
statement is made: ``Comments to CE154.'' The postcard will be date
stamped and returned to the commenter.
Background
On May 14, 1998, Cessna Aircraft Company applied to amend the Model
525 Type Certificate to add a new Model 525A. The Model 525A is a
derivative of the Model 525 currently approved under Type Certificate
Data Sheet A1WI.
The Cessna Model 525A, a derivative of the Model 525, will be
certified for operation to a maximum altitude of 45,000 feet. This will
be the first of this series to be approved above 41,000 feet. The
certification basis of the Model 525 was primarily 14 CFR part 23, as
amended by Amendments 23-1 through 23-40, plus special conditions. 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. Therefore, it is
necessary to develop special conditions that provide the level of
safety to that established by the regulations.
The FAA has previously issued Special Conditions No. 23-ACE-87, to
another small turbojet airplane model with requested approval for
operation up to 49,000 feet.
The FAA policy is to apply special conditions to part 23 airplanes
when the certified altitude exceeds the capability of the oxygen system
(in this case, the passenger system). This was the situation for a part
23 turbojet airplane. Thus, the special conditions were deemed to be
appropriate for the Cessna Model 525A and provide the basis for
formulating the special conditions described below:
Damage tolerance methods are proposed to assure pressure vessel
integrity while operating at the higher altitudes. Crack growth data is
used to prescribe an inspection program, which should detect cracks
before an opening in the pressure vessel would allow rapid
depressurization. Initial crack sizes for detection are determined
under 23.571 as amended by Amendment 23-48.
The cabin altitude after failure may not exceed the cabin altitude/
time history curve limits shown in Figures 3 and 4.
Continuous flow passenger oxygen equipment is certified 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. To prevent permanent physiological damage, the cabin altitude
must not exceed 25,000 feet for more than 2 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 the 37,000 foot limit of Figure 4 approaches
the physiological limits of the average person; therefore, every effort
must be made to provide the pilot 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 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
special conditions and for improbable failures not covered by the
special conditions, provided the cabin altitude is limited.
Type Certification Basis
Under the provisions of 21.101, Cessna Aircraft Company must show
that the Cessna Model 525A meets the applicable provisions of the
regulations incorporated by reference in Type Certificate Data Sheet
A1WI or the applicable regulations in effect on the date of application
for the change to the Cessna Model 525A. The regulations incorporated
by reference in the type certificate are commonly referred to as the
``original type certification basis.'' The regulations incorporated by
reference in Type Certificate Data Sheet A1WI are as follows:
(1) Part 23 of the Federal Aviation Regulations effective February
1, 1965, as amended by Amendments 23-1 through 23-40;
(a) In addition, if the regulations incorporated by reference do
not provide adequate standards with respect to the change, the
applicant must comply with certain regulations in effect on the date of
application for the change. The FAA has determined that the Cessna
Model 525A must also be shown to comply with the following sections of
part 23:
Federal Aviation Regulations Secs. 23.331, 23.351, 23.421, 23.423,
23.425, 23.427, 23.939, and 23.1163 as amended by Amendments 23-1
through 23-42;
Federal Aviation Regulations Secs. 23.943, 23.951, 23.957, 23.961,
23.967, 23.991, 23.993, 23.997, 23.999, 23.1001, 23.1011, 23.1019,
23.1041, 23.1061, 23.1189, 23.1322, 23.1357, 23.1391, 23.1393, 23.1395,
and 23.1445 as amended by Amendments 23-1 through 23-43;
Federal Aviation Regulations Secs. 23.305, 23.321, 23.361, 23.397,
23.479, 23.485, 23.613, 23.615, 23.621, 23.731 and 23.1549 as amended
by Amendments 23-1 through 23-45;
Federal Aviation Regulations Secs. 23.335, 23.337, 23.341, 23.343,
23.345, 23.347, 23.371, 23.393, 23.399, 23.415, 23.441, 23.443, 23.455,
23.457, 23.473, 23.499, 23.561, 23.571, 23.572, 23.611, 23.629, 23.673,
and 23.725 as amended by Amendments 23-1 through 23-48;
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Federal Aviation Regulations Secs. 23.677, 23.723, 23.785, 23.787,
23.791, 23.853, 23.855, 23.1303, 23.1307, 23.1321, 23.1351, 23.1353,
23.1361, and 23.1401 as amended by Amendments 23-1 through 23-49;
Federal Aviation Regulations Secs. 23.233, 23.235, 23.1555, and
23.1589 as amended by Amendments 23-1 through 23-50;
Federal Aviation Regulations Secs. 23.901, 23.903, 23.929, 23.963,
23.965, 23.1013, 23.1043, 23.1143, 23.1183, 23.1191, and 23.1337 as
amended by Amendments 23-1 through 23-51;
(2) Federal Aviation Regulations part 36 effective December 1,
1969, as amended by Amendments 36-1 through the amendment in effect at
the time of TC issuance.
(3) Federal Aviation Regulations part 34 effective September 10,
1990, as amended by Amendment 34-1, Fuel Venting and Exhaust Emission
Requirements for Turbine Engine Powered Airplanes.
(4) Special Conditions as follows:
(a) 23-ACE-55, additional requirements for engine location,
performance, characteristics, and protection of electronic systems from
lightning and high intensity radiated electromagnetic fields (HIRF).
(b) Special conditions adopted by this rulemaking action.
(5) Exemption: Exemption number 5759 granted. Model 525A to use
Federal Aviation Regulations Sec. 25.181 in lieu of damping criteria of
Federal Aviation Regulations Sec. 23.181(b).
(6) Compliance with ice protection will be demonstrated in
accordance with Federal Aviation Regulations Sec. 23.1419.
If the Administrator finds that the applicable airworthiness
regulations (i.e., part 23) do not contain adequate or appropriate
safety standards for the Cessna Model 525A because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Model 525A must comply with the part 23 fuel vent and
exhaust emission requirements of 14 CFR part 34 and the part 23 noise
certification requirements of 14 CFR part 36, and the FAA must issue a
finding of regulatory adequacy pursuant to Sec. 611 of Public Law 92-
574, the ``Noise Control Act of 1972.''
Special conditions, as appropriate, are issued in accordance with
Sec. 11.49 after public notice, as required by Secs. 11.28 and
11.29(b), and become part of the type certification basis in accordance
with 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 21.101(a)(1).
Novel or Unusual Design Features
The Model 525A will incorporate the following novel or unusual
design features:
The methods used to ensure pressure vessel integrity and to provide
ventilation, air conditioning, and pressurization will be unique due to
the operating altitude of this airplane.
Applicability
As discussed above, these special conditions are applicable to the
Cessna Model 525A. Should the Cessna Aircraft Company apply at a later
date for a change to the type 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
21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on one model of airplane. It is not a rule of general applicability,
and it affects only the applicant who applied to the FAA for approval
of these features on the airplane.
List of Subjects in 14 CFR Part 23
Aircraft, Aviation safety, Signs and symbols.
Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and
21.17; and 14 CFR 11.28 and 11.29(b).
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the Cessna Aircraft Company Model 525A airplane.
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.
2. Ventilation
In addition to the requirements of Sec. 23.831(b), 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 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
no more than 8,000 feet.
3. Air Conditioning
In addition to the requirements of Sec. 23.831, 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. 23.841, 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, in conjunction with any undetected, latent malfunctions or
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
[[Page 49416]]
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 4a and 4b of these
special conditions (Pressurization), it may be assumed that an
emergency descent is made by an 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 Cessna 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) In addition to the requirements of Sec. 23.1441(d), the
following applies: A quick-donning oxygen mask system with a pressure-
demand, mask mounted regulator must be provided for the flightcrew. It
must be shown that each quick-donning mask can, with one hand and
within 5 seconds, be placed on the face from its ready position,
properly secured, sealed, and supplying oxygen upon demand.
(b) In addition to the requirements of Sec. 23.1443, the following
applies: A continuous flow oxygen system must be provided for each
passenger.
(c) In addition to the requirements of Sec. 23.1445, the following
applies: If the flightcrew and passengers share a common source of
oxygen, a means to separately reserve the minimum supply required by
the flightcrew must be provided.
BILLING CODE 4910-13-P
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Issued in Kansas City, Missouri on August 31, 1999.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-23719 Filed 9-10-99; 8:45 am]
BILLING CODE 4910-13-C
