[Federal Register Volume 64, Number 229 (Tuesday, November 30, 1999)]
[Rules and Regulations]
[Pages 66719-66721]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-31040]
[[Page 66719]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE156, Special Condition 23-100-SC]
Special Conditions; Piper Cheyenne PA-31T2; Protection of Systems
for 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 to Carpenter Avionics,
Inc., 624-B Fitzhugh Blvd., Smyrna Airport, Smyrna, Tennessee 37167,
for a Supplemental Type Certificate for the Piper Cheyenne PA-31T2
airplane. This airplane will have novel and unusual design features
when compared to the state of technology envisaged in the applicable
airworthiness standards. These novel and unusual design features
include the installation of electronic flight instrument system (EFIS)
displays for which the applicable regulations do not contain adequate
or appropriate airworthiness 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 the airworthiness standards applicable to these
airplanes.
DATES: The effective date of these special conditions is November 18,
1999. Comments must be received on or before December 30, 1999.
ADDRESSES: Comments may be mailed in duplicate to: Federal Aviation
Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk,
Docket No. CE156, Room 506, 901 Locust, Kansas City, Missouri 64106.
All comments must be marked: Docket No. CE156. 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: Ervin Dvorak, Aerospace Engineer,
Standards Office (ACE-110), Small Airplane Directorate, Aircraft
Certification Service, Federal Aviation Administration, 901 Locust,
Room 301, Kansas City, Missouri 64106; telephone (816) 329-4123, or Les
Taylor, Aerospace Engineer, at the same address, telephone (816) 329-
4134.
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 or notice 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. The
special conditions may be changed in light of the comments received.
All comments received 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. Commenters wishing the FAA to acknowledge receipt of their
comments submitted in response to this notice must include a self-
addressed, stamped postcard on which the following statement is made:
``Comments to Docket No. CE156.'' The postcard will be date stamped and
returned to the commenter.
Background
On June 25, 1999, Carpenter Avionics Inc., 624-B Fitzhugh Blvd.,
Smyrna Airport, Smyrna, Tennessee 37167, made an application to the FAA
for a new Supplemental Type Certificate for the Piper Cheyenne PA-31T2
airplane. The Cheyenne is currently approved under TC No. A8EA. The
proposed modification incorporates a novel or unusual design feature,
such as digital avionics consisting of an EFIS, that is vulnerable to
HIRF external to the airplane.
Type Certification Basis
Under the provisions of 14 CFR part 21, Sec. 21.101, Carpenter
Avionics, Inc. must show that the Piper Cheyenne PA-31T2 aircraft meets
the following provisions, or the applicable regulations in effect on
the date of application for the change to the Cheyenne PA-31T2: CAR 3
effective May 15, 1956, through Amendment 3-8, effective December 18,
1962; FAR 23.205, 23.1545, 23.1563 and 23.1583, as amended by Amendment
23-3, effective November 11, 1965; and FAR 23.1557(c) as amended by
Amendment 23-7, effective September 14, 1969; and the Eastern Region
Engineering and Manufacturing Branch letter of December 6, 1965,
addressing the showing of equivalent safety with regard to CAR 3.682,
3.771 and 3.772. Special Conditions No. 23-3-EA-1, Docket No. 9245,
including Amendment No. 1 and AEA-210 letter of November 11, 1971, as
amended by AEA-210 letter of February 1, 1978, referring to Amendment
23-14 and FAR 23.991 as amended by Amendment 23-7, effective September
14, 1969. Noise Certification--FAR 36 up to Amendment 10, as
applicable. Fuel Venting Emissions--SFAR 27 up to Amendment 3, as
applicable, and Sec. 23.1301 of Amendment 23-20; Secs. 23.1309,
23.1311, and 23.1321 of Amendment 23-49; and Sec. 23.1322 of Amendment
23-43; exemptions, if any; and the special conditions adopted by this
rulemaking action.
Discussion
If the Administrator finds that the applicable airworthiness
standards do not contain adequate or appropriate safety standards
because of novel or unusual design features of an airplane, special
conditions are prescribed under the provisions of Sec. 21.16.
Special conditions are normally issued in accordance with
Sec. 11.49, as required by Secs. 11.28 and 11.29(b), and become a 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 already 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
Carpenter Avionics Inc. plans to incorporate certain novel and
unusual design features into an airplane for which the airworthiness
standards do not contain adequate or appropriate safety standards for
protection from the effects of HIRF. These features include EFIS, which
are susceptible to the HIRF environment, that were not envisaged by the
existing regulations for this type of airplane.
Protection of Systems from High Intensity Radiated Fields (HIRF):
Recent advances in technology have given rise to the application in
aircraft designs of
[[Page 66720]]
advanced electrical and electronic systems that perform functions
required for continued safe flight and landing. Due to the use of
sensitive solid state advanced components in analog and digital
electronics circuits, these advanced systems are readily responsive to
the transient effects of induced electrical current and voltage caused
by the HIRF. The HIRF can degrade electronic systems performance by
damaging components or upsetting system functions.
Furthermore, the HIRF environment has undergone a transformation
that was not foreseen when the current requirements were developed.
Higher energy levels are radiated from transmitters that are used for
radar, radio, and television. Also, the number of transmitters has
increased significantly. There is also uncertainty concerning the
effectiveness of airframe shielding for HIRF. Furthermore, coupling to
cockpit-installed equipment through the cockpit window apertures is
undefined.
The combined effect of the technological advances in airplane
design and the changing environment has resulted in an increased level
of vulnerability of electrical and electronic systems required for the
continued safe flight and landing of the airplane. Effective measures
against the effects of exposure to HIRF must be provided by the design
and installation of these systems. The accepted maximum energy levels
in which civilian airplane system installations must be capable of
operating safely are based on surveys and analysis of existing radio
frequency emitters. These special conditions require that the airplane
be evaluated under these energy levels for the protection of the
electronic system and its associated wiring harness. These external
threat levels, which are lower than previous required values, are
believed to represent the worst case to which an airplane would be
exposed in the operating environment.
These special conditions require qualification of systems that
perform critical functions, as installed in aircraft, to the defined
HIRF environment in paragraph 1 or, as an option to a fixed value using
laboratory tests, in paragraph 2, as follows:
(1) The applicant may demonstrate that the operation and
operational capability of the installed electrical and electronic
systems that perform critical functions are not adversely affected when
the aircraft is exposed to the HIRF environment defined below:
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Field strength
(volts per
Frequency meter)
----------------
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
------------------------------------------------------------------------
The field strengths are expressed in terms of peak root-mean-square
(rms) values.
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or,
(2) The applicant may demonstrate by a system test and analysis
that the electrical and electronic systems that perform critical
functions can withstand a minimum threat of 100 volts per meter, peak
electrical field strength, from 10 kHz to 18 GHz. When using this test
to show compliance with the HIRF requirements, no credit is given for
signal attenuation due to installation.
A preliminary hazard analysis must be performed by the applicant,
for approval by the FAA, to identify either electrical or electronic
systems that perform critical functions. The term ``critical'' means
those functions whose failure would contribute to, or cause, a failure
condition that would prevent the continued safe flight and landing of
the airplane. The systems identified by the hazard analysis that
perform critical functions are candidates for the application of HIRF
requirements. A system may perform both critical and non-critical
functions. Primary electronic flight display systems, and their
associated components, perform critical functions such as attitude,
altitude, and airspeed indication. The HIRF requirements apply only to
critical functions.
Compliance with HIRF requirements may be demonstrated by tests,
analysis, models, similarity with existing systems, or any combination
of these. Service experience alone is not acceptable since normal
flight operations may not include an exposure to the HIRF environment.
Reliance on a system with similar design features for redundancy as a
means of protection against the effects of external HIRF is generally
insufficient since all elements of a redundant system are likely to be
exposed to the fields concurrently.
Applicability
As discussed above, these special conditions are applicable to
Piper Cheyenne PA-31T2 airplane. Should Carpenter Avionics Inc. apply
at a later date for a supplemental type certificate to modify any other
model on the same type certificate to incorporate the same novel or
unusual design feature, the special conditions would apply to that
model as well under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain novel or unusual design features
on one model of airplane. 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 has been subjected to the
notice and comment period 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 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 23
Aircraft, Aviation safety, Signs and symbols.
Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR part 21,
Secs. 21.16 and 21.101; and 14 CFR part 11, Secs. 11.28 and 11.49.
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 Piper Cheyenne PA-31T2 airplane
modified by Carpenter Avionics Inc. to add an EFIS.
1. Protection of Electrical and Electronic Systems from High
Intensity Radiated Fields (HIRF). Each system
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that performs critical functions must be designed and installed to
ensure that the operations, and operational capabilities of these
systems to perform critical functions, are not adversely affected when
the airplane is exposed to high intensity radiated electromagnetic
fields external to the airplane.
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 Kansas City, Missouri, on November 18, 1999.
Marvin R. Nuss,
Acting Manager, Small Airplane Directorate.
[FR Doc. 99-31040 Filed 11-29-99; 8:45 am]
BILLING CODE 4910-13-P
