[Federal Register Volume 60, Number 115 (Thursday, June 15, 1995)]
[Rules and Regulations]
[Pages 31384-31386]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-14660]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-110; Special Conditions No. 25-ANM-100]
Special Conditions: Modified Gulfstream American Corporation
Model 1159 Airplane; High Intensity Radiated Fields (HIRF)
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Gulfstream
American Corporation (GAC) Model 1159 airplane, modified by Learjet,
Inc., of Denver, Colorado. This airplane will be
[[Page 31385]] equipped with a digital Electronic Flight Instrument
System (EFIS) that will perform critical functions. The applicable
regulations do not contain adequate or appropriate safety standards for
the protection of the EFIS from the effects of high-intensity radiated
fields (HIRF). These special conditions provide the additional safety
standards that the Administrator considers necessary to ensure that the
critical functions performed by this system are maintained when the
airplane is exposed to HIRF.
DATES: The effective date of these special conditions is May 26, 1995.
Comments must be received on or before July 31, 1995.
ADDRESSES: Comments on these final special conditions, request for
comments, may be mailed in duplicate to: Federal Aviation
Administration, Office of the Assistant Chief Counsel, Attn: Rules
Docket (ANM-7), Docket No. NM-110, 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-110.'' 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:
Mark Quam, FAA, Standardization Branch, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98055-4056; telephone (206) 227-2145.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA has determined that good cause exists for making these
special conditions effective upon issuance; however, interested persons
are invited to submit 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-110.'' The postcard will
be date stamped and returned to the commenter.
Background
On March 27, 1995, Learjet, Inc., of Denver, Colorado, applied for
a supplemental type certificate to modify the Gulfstream American
Corporation (GAC) Model 1159 airplane. The GAC Model 1159 airplane is a
business jet with two aft-mounted turbofan engines. The airplane can
carry two pilots and 19 passengers, depending on the exit and interior
configuration, and is capable of operating to an altitude of 45,000
feet. The original equipment installed in these airplanes presented the
required flight information in the form of analog displays. The
proposed modification incorporates the installation of a five tube
digital Electronic Flight Instrument System (EFIS) that displays
required flight critical information and critical functions. The
installation of the EFIS system displaying critical functions is
potentially vulnerable to high-intensity radiated fields (HIRF)
external to the airplane.
Supplemental Type Certification Basis
Under the provisions of Sec. 21.101 of the Federal Aviation
Regulations (FAR), Learjet, Inc., must show that the altered GAC Model
1159 airplane continues to meet the applicable provisions of the
regulations incorporated by reference in Type Certificate No. A12EA, or
the applicable regulations in effect on the date of application for the
change. 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 No.
A12EA include the following for the GAC Model 1159 airplanes: Civil
Aviation Regulation (CAR) 4b dated December 31, 1953, including
Amendments 4b-1 through 4b-14, Special Regulations SR422B and SR450A.
In addition, under Sec. 21.101(b)(1), the following sections of the FAR
apply to the EFIS installation: 25.1301(d), 25.1303, and 25.1322, as
amended by Amendment 25-38; and 25.1309, 25.1321(a)(b)(d), and (e),
25.1331, 25.1333, and 25.1335, as amended by Amendment 25-41. These
special conditions will form an additional part of the supplemental
type certification basis.
If the Administrator finds that the applicable airworthiness
regulations (i.e., CAR 4b or part 25, as amended) do not contain
adequate or appropriate safety standards for the GAC Model 1159
airplane because of a novel of 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 applicant apply for a supplemental type
certificate to modify any other model included on the same type
certificate 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).
Discussion
There is no specific regulation that addresses protection
requirements for electrical and electric systems from high-intensity
radiated fields (HIRF). Increased power levels from ground-based radio
transmitters, and the growing use of sensitive electrical and
electronic systems to command and control airplanes, 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 needed for the modified GAC Model 1159 airplanes that
would require that the EFIS be designed and installed to preclude
component damage and interruption of function due to the effects of
HIRF.
With the trend toward increased power levels from ground-based
transmitters, plus the advent of space and satellite communications,
coupled with electronic command and control of the airplane, the
immunity of critical digital avionics systems, such as the EFIS, to
HIRF must be established.
It is not possible to precisely define the HIRF to which the
airplanes will be exposed in service. There is also uncertainty
concerning the effectiveness of airframe shielding for HIRF.
Furthermore, coupling of electromagnetic energy to cockpit-installed
equipment through the cockpit window apertures is undefined. Based on
surveys and analysis of existing HIRF emitters, an adequate level of
protection exists when compliance with the HIRF protection special
condition is shown with either paragraphs 1 or 2 below: [[Page 31386]]
1. A minimum threat of 100 volts per meter peak electric field
strength from 10 KHz to 18 GHz.
a. The treat must be applied to the system elements and their
associated wiring harnesses without the benefit of airframe shielding.
b. Demonstration of this level of protection is established through
system tests and analysis.
2. A threat external to the airframe of the following field
strengths for the frequency ranges indicated:
------------------------------------------------------------------------
Peak (V/ Average
Frequency M) (V/M)
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10 KHz-100 KHz...................................... 50 50
100 KHz-500 KHz..................................... 60 60
500 KHz-2000 KHz.................................... 70 70
2 MHz-30 MHz........................................ 200 200
30 MHz-70 MHz....................................... 30 30
70 MHz-100 MHz...................................... 30 30
100 MHz-200 MHz..................................... 150 33
200 MHz-400 MHz..................................... 70 70
400 MHz-700 MHz..................................... 4,020 935
700 MHz-1000 MHz.................................... 1,700 170
1 GHz-2 GHz......................................... 5,000 990
2 GHz-4 GHz......................................... 6,680 840
4 GHz-6 GHz......................................... 6,850 310
6 GHz-8 GHz......................................... 3,600 670
8 GHz-12 GHz........................................ 3,500 1,270
12 GHz-18 GHz....................................... 3,500 360
18 GHz-40 GHz....................................... 2,100 750
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As discussed above, these special conditions are applicable to the
GAC Model 1159 airplane, modified by Learjet, Inc. Should Learjet, Inc.
apply at a later date for a supplemental type certificate to modify any
other model included on Type Certificate No. A12EA to incorporate 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 only certain unusual or novel design features
on GAC Model 1159 airplanes modified by Learjet, Inc. It is not a rule
of general applicability and affects only the applicant who applied to
the FAA for approval of this feature on this airplane.
The substance of these special conditions has been subjected to the
notice and comment procedure in several prior instances and has been
derived without substantive change from those previously issued. It is
unlikely that prior public comment would result in a significant change
from the substance contained herein. For this reason, and because a
delay would significantly affect the certification of the airplane,
which is imminent, the FAA has determined that prior public notice and
comment are unnecessary and impracticable, and good cause exists for
adopting these special conditions immediately. Therefore these special
conditions are being made effective upon issuance. The FAA is
requesting comments to allow interested persons to submit views that
may not have been submitted in response to the prior opportunities for
comment described above.
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, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the supplemental type certification basis for the GAC Model 1159
airplane, as modified by Learjet, Inc.:
1. Protection from Unwanted Effects of High-Intensity Radiated
Fields (HIRF). Each electrical and electronic system that performs
critical functions must be designed and installed to ensure that the
operation and operational capability of these systems to perform
critical functions are not adversely affected when the airplane is
exposed to high intensity radiated fields external to the airplane.
2. The following definition applies with respect to this special
condition: Critical Function. Functions whose failure would contribute
to or cause a failure condition that would prevent the continued safe
flight and landing of the airplane.
Issued in Renton, Washington, on May 26, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-14660 Filed 6-14-95; 8:45 am]
BILLING CODE 4910-13-U
