[Federal Register Volume 59, Number 109 (Wednesday, June 8, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-13909]


[[Page Unknown]]

[Federal Register: June 8, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-97; Special Conditions No. 25-ANM-86]

 

Special Conditions: Modified Gulfstream G-1159A Series Airplanes, 
High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions with request for comments.

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SUMMARY: These special conditions are issued for the Gulfstream G-1159A 
series airplanes modified by ElectroSonics, Division of AiRadio 
Corporation of Columbus, Ohio. These airplanes are equipped with 
digital electronic flight instrument systems (EFIS) that perform 
critical functions. The applicable type certification regulations do 
not contain adequate or appropriate safety standards for the protection 
of these systems 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 that these systems perform are maintained when the 
airplane is exposed to HIRF.

DATES: The effective date of these special conditions is May 31, 1994. 
Comments must be received on or before July 25, 1994.

ADDRESSES: Comments on these special conditions may be mailed in 
triplicate to: Federal Aviation Administration, Transport Airplane 
Directorate (ANM-100), Attn: Docket No. NM-97, 1601 Lind Avenue SW., 
Renton, WA 98055-4056; or delivered in triplicate to the Transport 
Airplane Directorate at the above address. Comments must be marked; 
Docket No. NM-97. Comments may be inspected weekdays, except Federal 
holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT:
Michael Zielinski, FAA, Standardization Branch, ANM-113, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, WA 98055-4056, telephone (206) 227-2279.

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 or 
special conditions number and be submitted in triplicate 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 a available in the 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-97.'' The postcard will 
be date stamped, and returned to the commenter.

Background

    On March 25, 1994, ElectroSonics, Division of AiRadio Corporation 
of Columbus, Ohio, applied for a supplemental type certificate to 
modify the Gulfstream G-1159A series airplanes. The Gulfstream G-1159A 
is a business jet with two aft-mounted turbojet engines. The airplane 
can carry two pilots and up to 19 passengers, depending on the exit and 
interior configuration, and is capable of operating to 45,000 feet 
altitude. The proposed modification incorporates the installation of 
digital avionics consisting of an electronic flight instrument system 
(EFIS) that is potentially vulnerable to HIRF external to the airplane.

Supplemental Type Certification Basis

    Under the provisions of Sec. 21.101 of the FAR, ElectroSonics, 
Division of AiRadio Corporation, must show that the modified Gulfstream 
G-1159A series airplanes continue 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 Certification No. 
A12EA include the following: CAR4b of the Civil Aviation Regulations, 
dated December 31, 1953, including Amendments 4b-1 through 4b-14. In 
addition the following Federal Aviation Regulations (FAR) apply to the 
EFIS installation: Secs. 25.1303(b) and 25.1322, as amended through 
Amendment 25-38; Secs. 25.1309, 251321 (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., part 25, as amended) do not contain adequate or 
appropriate safety standards for the Gulfstream G-1159A series 
airplanes because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of Sec. 21.6 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).

Discussion

    There is no specific regulation that addresses protection 
requirements for electrical and electronic systems from 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 Gulfstream G-1159A series airplanes that 
would require that new technology electrical and electronic systems, 
such as EFIS and digital avionics systems be designed and installed to 
preclude component damage and interruption of function due to both the 
direct and indirect effects of HIRF.
    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).

High-Intensity Radiated Fields (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 
airplane 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:
    1. A minimum threat of 100 volts per meter peak electric field 
strength from 10 KHz to 18 GHz.
    a. The threat 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) 
------------------------------------------------------------------------
10 KHz-100 KHz......................................        50        50
100 KHz-500 KHz.....................................        60        60
500 KHz-2 MHz.......................................        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-1 GHz.......................................     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      1270
12 GHz-18 GHz.......................................     3,500       360
18 GHz-40 GHz.......................................     2,100       750
------------------------------------------------------------------------

    The envelope given in paragraph 2 above is a revision to the 
envelope used in previously issued special conditions in other 
certification projects. It is based on new data and SAE AE4R 
subcommittee recommendations. This revised envelope includes data from 
Western Europe and the U.S. It will also be adopted by the European 
Joint Aviation Authorities.
    As discussed above, these special conditions are applicable to the 
Gulfstream G-1159A series airplanes, modified by ElectroSonics, 
Division of AiRadio Corporation of Columbus, Ohio. Should ElectroSonics 
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 the Gulfstream G-1159A series airplanes modified by ElectroSonics, 
Division of AiRadio Corporation of Columbus, Ohio. 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 Gulfstream G-1159A series 
airplanes modified by ElectroSonics, Division of AiRadio Corporation of 
Columbus, Ohio.
    The substance of the special conditions for these airplanes 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 have not been submitted in 
response to the prior opportunities for comment described above.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Federal Aviation Administration, 
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 Gulfstream G-1159A series 
airplanes modified by ElectroSonics, Division of AiRadio Corporation of 
Columbus, Ohio.
    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 definitions apply with respect to these special 
conditions:
    Critical Functions. 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 31, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-13909 Filed 6-7-94; 8:45 am]
BILLING CODE 4910-13-M