[Federal Register Volume 62, Number 47 (Tuesday, March 11, 1997)]
[Rules and Regulations]
[Pages 11072-11073]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5900]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-137; Special Condition No. 25-ANM-123]


Special Condition: Boeing Model 747-200B, High-Intensity Radiated 
Fields

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special condition; request for comments.

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SUMMARY: This special condition is issued for the Boeing Model 747-200B 
airplanes. This airplane, as modified by ARINC Incorporated, utilizes 
new avionics/electronic systems, such as the electronic flight 
information systems (EFIS), which perform critical functions. The 
applicable regulations do not contain adequate or appropriate safety 
standards for the protection of these systems from the effects of high-
intensity radiated fields (HIRF). This special condition contains 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: The effective date of this special condition is February 12, 
1997.
    Comments must be received on or before April 25, 1997.

ADDRESSES: Comments on this special condition may be mailed in 
duplicate to: Federal Aviation Administration, Office of the Assistant 
Chief Counsel, Attn: Rules Docket (ANM-7), Docket No. NM-137, 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-137. 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, ANM-113, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, Washington, 98055-4056; telephone (206) 227-2145; facsimile 
(206) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that good cause exists for making this 
special condition 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 condition 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. This special 
condition 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-137.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On January 26, 1995, ARINC Incorporated of Annapolis, Maryland, 
applied for a Supplemental Type Certificate (STC) to incorporate the 
installation of an Allied-Signal (Bendix King) EFIS-10 Electronic 
Flight Instrument System (EFIS) on a Boeing Model 747-200B airplane. 
The installation may be vulnerable to high-intensity radiated fields 
(HIRF) external to the airplane.
    Boeing Model 747-200B series airplanes are listed on Type 
Certificate (TC) A20WE. The airplanes are pressurized, large transport 
type airplanes powered by four wing-mounted turbofan engines.

Type Certification Basis

    Under the provisions of Sec. 21.101 of 14 CFR part 21, ARINC 
Incorporated must show that the modified Boeing Model 747-200B 
continues to meet the applicable provisions of the regulations 
incorporated by reference in TC 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 TC A20WE include the following for the 
Boeing Model 747-200B series airplanes: 14 CFR part 25, dated February 
1, 1965, as amended by Amendments 25-1 through 25-8, plus Amendments 
25-15, 25-17, 25-18, 25-20, and 25-39. In addition, under 
Sec. 21.101(b)(1), the following regulations apply to the EFIS 
installation: Secs. 25.1303(b) and 25.1322, as amended by Amendment 25-
38; Secs. 25.1309, 25.1321(a)(b) (d) and (e), 25.1331, 25.1333, and 
25.1355 as amended by Amendment 25-41; and Sec. 25.1316 as amended by 
Amendment 25-80. This special condition will form an additional part of 
the 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 Boeing Model 747-200B 
series 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 
14 CFR part 11, 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).

Novel or Unusual Design Features

    The Boeing Model 747-200B incorporates new avionics/electronic 
systems, such as the electronic flight instrument system (EFIS), that 
perform critical functions. These systems may be vulnerable to HIRF 
external to the airplane.

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, a special 
condition is needed for the Boeing Model 747-200B, as

[[Page 11073]]

modified by ARINC Incorporated, which requires that new electrical and 
electronic systems that perform critical functions be designed and 
installed to preclude component damage and interruption of function due 
to both the direct and indirect 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 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-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     1,270
12 GHz-18 GHz.......................................     3,500       360
18 GHz-40 GHz.......................................     2,100       750
------------------------------------------------------------------------

    As discussed above, this special condition is applicable to the 
Boeing Model 747-200B airplanes, as modified by ARINC Incorporated. 
Should ARINC Incorporated 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, this 
special condition would apply to that model as well, under the 
provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain design features on the Boeing 
Model 747-200B airplanes. It is not a rule of general applicability and 
affects only the applicant who applied to the FAA for approval of these 
features on the airplane.
    The substance of the special condition for this airplane 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 this special condition immediately. 
Therefore, this special condition is 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 this special condition is as follows:

    Authority: 49 U.S.C. 106(f), 40113, 44701, 44702, 44704.

The Special Condition

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special condition is issued as part of the 
type certification basis for the Boeing Model 747-200B airplane, as 
modified by ARINC Incorporated.
    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.
    2. For the purpose of this special condition, the following 
definition applies: 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 February 12, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 97-5900 Filed 3-10-97; 8:45 am]
BILLING CODE 4910-13-M