[Federal Register Volume 64, Number 230 (Wednesday, December 1, 1999)]
[Rules and Regulations]
[Pages 67147-67148]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31185]



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 Rules and Regulations
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  Federal Register / Vol. 64, No. 230 / Wednesday, December 1, 1999 / 
Rules and Regulations  

[[Page 67147]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM158; Special Conditions No. 25-152-SC]


Special Conditions: Boeing Model 767-400ER; High-Intensity 
Radiated Fields

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Boeing Model 767-
400ER airplane. This airplane will utilize new avionics/electronic 
systems that provide critical data to the flightcrew. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for the protection of these systems from the effects of high-
intensity radiated fields. These special conditions provide the 
additional safety standards that the Administrator considers necessary 
to establish a level of safety equivalent to that established by the 
existing airworthiness standards.

EFFECTIVE DATE: January 3, 2000.

FOR FURTHER INFORMATION CONTACT: Massoud Sadeghi, FAA, Transport 
Airplane Directorate, Aircraft Certification Service, Airplane and 
Flight Crew Interface Branch, ANM-111, 1601 Lind Avenue SW., Renton, 
Washington, 98055-4056, telephone (425) 227-2117 or facsimile (425) 
227-1320.

SUPPLEMENTARY INFORMATION:

Background

    On January 14, 1997, the Boeing Commercial Airplane Group applied 
for an amendment to Type Certificate No. A1NM to include the new Model 
767-400ER, a derivative of the Model 767-200/300 series airplanes. The 
Model 767-400ER is a swept-wing, conventional-tail, twin-engine, 
turbofan-powered transport airplane. The airframe has been strengthened 
to accommodate the increased design loads and weights. The airplane has 
a seating capacity of up to 375, and a maximum takeoff weight of 
450,000 pounds (204,120 kg). Each engine will be capable of delivering 
62,000 pounds of thrust. The flight controls are unchanged beyond those 
changes deemed necessary to accommodate the stretched configuration.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Boeing must show that the 
Model 767-400ER airplane meets the applicable provisions of the 
regulations incorporated by reference in Type Certificate No. A1NM, 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. A1NM include 14 CFR part 25, as amended by 
Amendments 25-1 through 25-45 with a few exceptions, and certain other 
later amended sections of part 25 that are not relevant to these 
special conditions. Except for certain earlier amended sections of part 
25 that are not relevant to these special conditions, Boeing has chosen 
to comply with part 25 as amended by Amendments 25-1 through 25-89, the 
applicable regulations in effect on the date of application.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model 767-400ER must comply with the fuel vent and 
exhaust emission requirements of part 34, effective September 10, 1990, 
plus any amendments in effect at the time of certification; and the 
noise certification requirements of part 36, effective December 1, 
1969, as amended by Amendment 36-1 through the amendment in effect at 
the time of certification.
    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 Model 767-400ER because of a novel 
or unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49, as required by Secs. 11.28 and 11.29(b), 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 type certificate for that model be amended 
later to include any other model that incorporates the same novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified 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 Model 767-400ER airplane will utilize electrical and electronic 
systems that perform critical functions, including the following: 
primary electronic flight displays and full authority digital engine 
controls (FADEC). These systems may be vulnerable to high-intensity 
radiated fields (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, special 
conditions are needed for the Model 767-400ER. The Model 767-400 
requires that new technology electrical and electronic systems 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 and the use 
of composite material in the airplane structure, the immunity of 
critical digital avionics systems to HIRF must be established.

[[Page 67148]]

    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 paragraph 1 or 2 below:
    1. A minimum threat of 100 volts rms per meter 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.

------------------------------------------------------------------------
                                                        Field strength
                                                       (volts per meter)
                      Frequency                      -------------------
                                                        Peak    Average
------------------------------------------------------------------------
10 kHz-100 kHz......................................       50         50
100 kHz-500 kHz.....................................       50         50
500 kHz-2 MHz.......................................       50         50
2 MHz-30 MHz........................................      100        100
30 MHz-70 MHz.......................................       50         50
70 MHz-100 MHz......................................       50         50
100 MHz-200 MHz.....................................      100        100
200 MHz-400 MHz.....................................      100        100
400 MHz-700 MHz.....................................      700         50
700 MHz-1 GHz.......................................      700        100
1 GHz-2 GHz.........................................     2000        200
2 GHz-4 GHz.........................................     3000        200
4 GHz-6 GHz.........................................     3000        200
6 GHz-8 GHz.........................................     1000        200
8 GHz-12 GHz........................................     3000        300
12 GHz-18 GHz.......................................     2000        200
18 GHz-40 GHz.......................................      600       200
------------------------------------------------------------------------
The field strengths are expressed in terms of peak root-mean-square
  (rms) values.

    The threat levels identified above are the result of an FAA review 
of existing studies on the subject of HIRF, in light of the ongoing 
work of the Electromagnetic Effects Harmonization Working Group of the 
Aviation Rulemaking Advisory Committee.

Applicability

    As discussed above, these special conditions would be applicable 
initially to the Model 767-400ER airplane. Should Boeing apply at a 
later date for a change to the type certificate to include another 
model incorporating the same novel or unusual design feature, these 
special conditions would apply to that model as well under the 
provisions of Sec. 21.101(a)(1).

Discussion of Comments

    Notice of proposed special conditions No. 25-99-06-SC was published 
in the Federal Register on July 21, 1999 (64 FR 39095). One comment in 
support of the special condition was received.

Conclusion

    This action affects certain design features only on the Model 767-
400ER. 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 airplane.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these proposed special conditions is as 
follows:

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

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for the Boeing 767-400ER series airplanes.
    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 November 17, 1999.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 99-31185 Filed 11-30-99; 8:45 am]
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