[Federal Register Volume 60, Number 38 (Monday, February 27, 1995)]
[Rules and Regulations]
[Pages 10486-10488]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-4773]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 25

[Docket No. NM-108; Special Conditions No. 25-ANM-96]


Special Conditions: Modified Gulfstream American Corporation 
Model G-IV 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 G-IV airplane modified by Duncan 
Aviation, Inc., of Lincoln, Nebraska. This airplane will be equipped 
with a Flight Visions Corporation, FV-2000 Head-Up Display System (HUD) 
that will perform critical functions. The applicable regulations do not 
contain adequate or appropriate safety standards for the protection of 
the HUD 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 February 13, 
1995. Comments must be received on or before April 13, 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-108, 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-108.'' 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:
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 [[Page 10487]] 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-108.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On August 16, 1994, Duncan Aviation, Inc., of Lincoln, Nebraska, 
applied for a supplemental type certificate to modify the Gulfstream 
American Corporation (GAC) Model G-IV airplane. The GAC Model G-IV 
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 proposed modification incorporates the installation 
of a digital avionics system that will present critical functions on 
the Head-up Display System (HUD), which 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), Duncan Aviation, Inc., must show that the altered 
GAC Model G-IV airplane continues to meet the applicable provisions of 
the regulations incorporated by reference in Type Certificate No. 
A12EU, 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. 
A12EU include the following for the GAC Model G-IV airplanes: 
Sec. 21.29 of 14 CFR part 21 and 14 CFR part 25, dated February 1, 
1965, as amended by Amendments 25-1 through 25-26. In addition, under 
Sec. 21.101(b)(1), the following sections of the FAR apply to the HUD 
installation: Sec. 25.1322, as amended by Amendment 25-38; and 
Secs. 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., part 25, as amended) do not contain adequate or 
appropriate safety standards for the GAC Model G-IV airplane 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 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 electronic 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 G-IV airplanes that 
would require that the HUD be designed and installed to preclude 
component damage and interruption of function due to the effects of 
HIRF.

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 HUD, 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:
    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-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
------------------------------------------------------------------------

    As discussed above, these special conditions are applicable to the 
GAC Model G-IV airplane, modified by Duncan Aviation. Should Duncan 
Aviation apply at a later date for a supplemental type certificate to 
modify any other model included on Type Certificate No. A12EU 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 G-IV airplanes modified by Duncan Aviation. 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 [[Page 10488]] 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 G-IV 
airplane, as modified by Duncan Aviation:
    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 February 13, 1995.
Darrell M. Pederson,
Assistant Manager, Transport Airplane Directorate, Aircraft 
Certification Service, ANM-101.
[FR Doc. 95-4773 Filed 2-24-95; 8:45 am]
BILLING CODE 4910-13-M