[Federal Register Volume 64, Number 159 (Wednesday, August 18, 1999)]
[Rules and Regulations]
[Pages 44817-44819]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-20858]



 ========================================================================
 Rules and Regulations
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains regulatory documents 
 having general applicability and legal effect, most of which are keyed 
 to and codified in the Code of Federal Regulations, which is published 
 under 50 titles pursuant to 44 U.S.C. 1510.
 
 The Code of Federal Regulations is sold by the Superintendent of Documents. 
 Prices of new books are listed in the first FEDERAL REGISTER issue of each 
 week.
 
 ========================================================================
 

  Federal Register / Vol. 64, No. 159 / Wednesday, August 18, 1999 / 
Rules and Regulations  

[[Page 44817]]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM161, Special Conditions No. 25-146-SC]


Special Conditions: GEC-Marconi; Boeing Model 737-800 Airplane; 
High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for the Boeing Model 737-
800 airplane, as modified by GEC-Marconi. The Model 737-800 is equipped 
with a high-technology digital avionics system that performs critical 
functions. The applicable type certification regulations do not contain 
adequate or appropriate safety standards for the protection of this 
system 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 
this system performs are maintained when the airplane is exposed to 
HIRF.

DATES: The effective date of these special conditions is July 29, 1999. 
Comments must be received on or before October 4, 1999.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attention: Rules Docket (ANM-114), Docket No. NM161, 1601 
Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in 
duplicate to the Transport Airplane Directorate at the above address. 
Comments must be marked: Docket No. NM161. 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: Gerry Lakin, FAA, Transport Airplane 
Directorate, Aircraft Certification Service, Standardization Branch, 
ANM-113, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-1187; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable because 
these procedures would significantly delay issuance of the approval 
design and thus delivery of the affected aircraft. In addition, the 
substance of these special conditions has been subject to the public 
comment process in several prior instances with no substantive comments 
received. The FAA therefore finds that good cause exists for making 
these special conditions effective upon issuance.

Comments Invited

    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. NM161.'' The postcard will be date stamped and returned to the 
commenter.

Background

    On September 28, 1998, the Los Angeles Aircraft Certification 
Office received an application from GEC-Marconi Avionics (GMA) Ltd., 
Airport Works, Rochester, Kent, England, for a supplemental type 
certificate to modify Type Certificate No. A16WE for the Boeing Model 
737-800.
    The Boeing Model 737-800 is a low-wing, pressurized airplane with 
twin, wing-mounted, jet engines that is configured for approximately 
162 passengers. The airplane has a maximum standard takeoff weight of 
155,500 pounds, a maximum landing weight of 146,300 pounds, a maximum 
operating altitude of 41,000 feet, and a range of 3370 nautical miles. 
The overall length of the Boeing Model 737-800 is 129 feet, 6 inches, 
the height is 41 feet, 2 inches, and the wing span is 112 feet, 7 
inches. The modification incorporates a head up display (HUD) system 
for display of critical flight parameters (altitude, airspeed, and 
attitude) to the crew. The display can be susceptible to disruption to 
both command/response signals as a result of electrical and magnetic 
interference. This disruption of signals could result in loss of all 
critical flight displays and annunciations or present misleading 
information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, GEC-Marconi must show that 
the Model 737-800 airplane, as changed, continues to meet the 
applicable provisions of the regulations incorporated by reference in 
Type Certificate No. A16WE 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 certifications basis.'' The certification basis for the 
modified Boeing Model 737-800 airplanes is as follows:
    For airworthiness and environmental standards for components and 
areas not affected by the change, the original certification basis for 
the Model 737-800 is shown on Type Certificate Data Sheet (TCDS) No. 
A15WE, revision 25, dated September 9, 1998. The Model 737-800 was 
certified to part 25, as amended by Amendments 25-1 though 25-77, with 
reversions to earlier Amendments, voluntary compliance to later 
Amendments, special conditions, equivalent safety findings and 
exemptions listed in the TCDS.
    For airworthiness and environmental standards for components and 
areas affected by the change, the certification basis for the Model 
737-800 is 14 CFR

[[Page 44818]]

part 25, effective February 1, 1965, including Amendments 25-1 through 
25-97, which is the amendment level in effect on the date of 
application.
    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 Model 737-800 airplane 
because of novel or unusual design features, special conditions are 
prescribed under the provisions of Sec. 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model 737-800 must comply with the part 25 fuel and 
exhaust emission requirements of 14 CFR part 34 and the part 25 noise 
certification requirements of 14 CFR part 36.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49, 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 GEC-Marconi apply at a later date 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, these special conditions would also apply to the other model 
under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    Boeing Model 737-800 will incorporate a head up display (HUD) 
system that performs critical functions. This system 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 applicable regulations incorporated by reference, 
special conditions are needed for the Boeing Model 737-800, which 
require that new electrical and electronic systems, such as the HUD, 
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 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.

------------------------------------------------------------------------
                                                       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. In general, these standards are 
less critical than the threat level that was previously used as the 
basis for some earlier special conditions.

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 737-800 airplanes modified by GEC-Marconi. Should GEC-
Marconi apply at a later date 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, these special 
conditions 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 Boeing Model 
737-800 airplanes modified by GEC-Marconi. 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 conditions 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 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. 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 Boeing Model 737-800 airplanes 
modified by GEC-Marconi.
    1. Protection from Unwanted Effects of High-Intensity Radiated 
Fields

[[Page 44819]]

(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.
    For the purpose of these special conditions, 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 July 29, 1999.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 99-20858 Filed 8-17-99; 8:45 am]
BILLING CODE 4910-13-U