[Federal Register Volume 60, Number 138 (Wednesday, July 19, 1995)]
[Rules and Regulations]
[Pages 36967-36969]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-17589]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-113; Special Conditions No. 25-ANM-101]


Special Conditions: Modified Boeing Company Model 747-100 and 
747-200 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 Boeing Company 
Model 747-100 and 747-200 modified by B & D Instruments & Avionics, 
Inc., of Valley Center, Kansas. This airplane will be equipped with a 
Flat Panel Engine Instrument Display that will perform critical 
functions. The applicable regulations do not contain 

[[Page 36968]]
adequate or appropriate safety standards for the protection of the Flat 
Panel Engine Instrument Display 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 September 5, 
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-113, 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-113.'' 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-113.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On April 7, 1995, B & D Instruments & Avionics, Inc., of Valley 
Center, Kansas, applied for a supplemental type certificate to replace 
the existing engine instruments (EPR, FF, N1, N2, EGT) with a Flat 
Panel Display System in the Boeing Company Model 747-100 and 747-200. 
The Model 747-100 is a passenger transport category airplane, and is 
capable of operating to an altitude of 45,100 feet. For all flights, 3 
persons (pilot, copilot, flight engineer) are required. The Model 747-
200 airplane is an extended range passenger version of the basic 747-
100 series aircraft. The airplanes can carry up to 550 passengers 
depending on the exit and interior configuration. The original 
equipment installed in these airplanes presented the required engine 
information in the form of analog displays. The proposed modification 
would replace the existing engine instruments (EPR, FF, N1, N2, EGT) 
with a digital Flat Panel Engine Instrument Display System. The 
installation of the Flat Panel Engine Instrument Display System 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), B & D Instruments & Avionics, Inc., must show that 
the altered Boeing Company Model 747-100 and 747-200 airplanes continue 
to meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. A20WE, 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. 
A20WE include the following for the Boeing Company Model 747-100 and 
747-200 airplanes:
    Part 25 of the FAR effective February 1, 1965, Amendments 25-1 
through 25-8 plus Amendments 25-15, 25-17, 25-18, 25-20, and 25-39 
transmitted by FAA letter dated February 4, 1977, and special 
conditions summarized for record purposes as enclosed with FAA letter 
to The Boeing Company dated February 20, 1970. In addition, the 
airplanes must be shown to meet the noise standards of part 36 of the 
FAR.
    In addition, under Sec. 21.101(b)(1), the following sections of the 
FAR apply to the Flat Panel Engine Instrument Display installation: 
Secs. 25.1301(d), 25.1305 and 25.1322, as amended by Amendment 25-38; 
and Secs. 25.1309, 25.1321 (a), (c), (d), and (e), 25.1331, 25.1337, as 
amended by Amendment 25-40. These special conditions 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 Boeing Company Model 747-100 and 
747-200 airplanes 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 Boeing Model 747-100 and 747-200 
airplanes that would require that the Flat Panel Engine Instrument 
Display System 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 Flat 

[[Page 36969]]
Panel Engine Instrument Display System, 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 which compliance with the HIRF protection special 
condition is shown with either paragraph 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    Average
                      Frequency                         (V/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-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 
Boeing Company Model 747-100 and 747-200 airplanes, modified by B & D 
Instruments & Avionics, Inc. Should B & D Instruments & Avionics, Inc. 
apply at a later date for a supplemental type certificate to modify any 
other model included on Type Certificate No. A20WE 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 Boeing Company Model 747-100 and 747-200 airplanes, modified by B & 
D Instruments & Avionics, 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 recodkeeping 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 Boeing Company Model 
747-100 and 747-200 airplanes, as modified by B & D Instruments & 
Avionics, 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 June 29, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 95-17589 Filed 7-18-95; 8:45 am]
BILLING CODE 4910-13-M