[Federal Register Volume 62, Number 98 (Wednesday, May 21, 1997)]
[Rules and Regulations]
[Pages 27687-27688]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-13264]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 62, No. 98 / Wednesday, May 21, 1997 / Rules
and Regulations
[[Page 27687]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-142; Special Conditions No. 25-ANM-126]
Special Conditions: McDonnell-Douglas Model DC-9-31/-32, High-
Intensity Radiated Fields
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for McDonnell-Douglas
Model DC-9-31/-32 airplanes as modified by Innovative Solutions &
Support, Inc. The Innovative Solutions & Support, Inc. altimeter P/N
9D-80110-2 will utilize an electronic system which performs a critical
function. 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). These special
conditions contain 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 these special conditions is May 13, 1997.
Comments must be received on or before July 7, 1997.
ADDRESSES: Comments on these special conditions may be mailed in
duplicate to: Federal Aviation Administration, Office of the Assistant
Chief Counsel, Attn: Rules Docket (ANM-7), Docket No. NM-142, 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-142. 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: Joe Jacobsen, Standardization Branch,
ANM-113, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone
(206) 227-2011.
SUPPLEMENTARY INFORMATION:
Comment 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 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. 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-142.'' The postcard will
be date stamped and returned to the commenter.
Background
On January 17, 1997, Innovative Solutions & Support, Inc. applied
for a supplemental type certificate to modify the altimeter system of
McDonnell-Douglas Model DC-9-31/-32 airplanes to an electronic system.
The Model DC-9-31/-32 is currently approved under Type Certificate No.
A6WE.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Innovative Solutions &
Support, Inc. must show that the Model DC-9-31/-32 airplanes meet the
applicable provisions of the regulations incorporated by reference in
Type Certificate No. A6WE or the applicable regulations in effect on
the date of application for the changes to the Model DC-9-31/-32. In
addition, the certification basis includes certain special conditions
and later amended sections of 14 CFR part 25 that are not relevant to
these special conditions.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate
or appropriate safety standards for the DC-9-31/-32 because of a novel
or unusual design feature, special conditions are prescribed under the
provisions of 14 CFR 21.16 to establish a level of safety equivalent to
that established in the regulations.
In addition to the applicable airworthiness regulations and special
conditions, the McDonnell Douglas DC-9-31/-32 must comply with the fuel
and exhaust emission requirements of 14 CFR part 34 and the noise
certification requirements of 14 CFR part 36.
Special conditions, as appropriate, are issued in accordance with
14 CFR 11.49 after public notice, as required by 14 CFR 11.28 and
11.29, and become part of the type certification basis in accordance
with 14 CFR 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 14 CFR 21.101(a)(1).
Novel or Unusual Design Features
The Model DC-9-31/-32, as modified, incorporates a new electronic
altimeter system. This system 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.
[[Page 27688]]
To ensure that a level of safety is achieved equivalent to that
intended by the regulations incorporated by reference, special
conditions are issued for the DC-9-31/-32, as modified by Innovative
Solutions & Support, Inc., which require that new technology electronic
systems, such as altimeter system, 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
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.
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Peak (V/ Average
Frequency M) (V/M)
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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
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As discussed above, these special conditions would be applicable
initially to the modified Model DC-9-31/-32. Should Innovative
Solutions & Support, Inc. 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 14 CFR 21.101(a)(1).
Conclusion
This action affects only certain design features on McDonnell-
Douglas DC-9-31/-32 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 these 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 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 McDonnell-Douglas DC-9-31/-32
airplane, as modified by Innovative Solutions & Support, 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.
2. 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 May 13, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 97-13264 Filed 5-20-97; 8:45 am]
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