[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]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 64, No. 159 / Wednesday, August 18, 1999 /
Rules and Regulations
[[Page 44817]]
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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.
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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.
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Field strength
(volts per meter)
Frequency ---------------------
Peak Average
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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
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The field strengths are expressed in terms of peak root-mean-square
(rms) values.
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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]
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