[Federal Register Volume 65, Number 8 (Wednesday, January 12, 2000)]
[Rules and Regulations]
[Pages 1758-1760]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-690]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE158, Special Condition 23-101-SC]
Special Conditions; Ayres Corporation Model LM-200 Loadmaster;
Protection of Systems for High Intensity Radiated Fields (HIRF)
AGENCY: Federal Aviation Administration (FAA), DOT.
[[Page 1759]]
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued to Ayres Corporation, One
Ayres Way, Post Office Box 3090, Albany, Georgia 31706-3090, for a Type
Certificate for the Ayres Corporation Model LM-200 Loadmaster 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 December 23,
1999. Comments must be received on or before February 11, 2000.
ADDRESSES: Comments may be mailed in duplicate to: Federal Aviation
Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk,
Docket No. CE158, Room 506, 901 Locust, Kansas City, Missouri 64106.
All comments must be marked: Docket No. CE158. 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. CE158.'' The postcard will be date stamped and
returned to the commenter.
Background
On May 6, 1996, Ayres Corporation made an application to the FAA
for a Type Certificate for their new Ayres Corporation Model LM-200
Loadmaster airplane with re-application made on March 12, 1999. The
Ayres Corporation Model LM-200 commuter category airplane has a twin
turbine LHTEC CTP800-4T powerplant with a maximum takeoff weight of
19,000 pounds. The airplane 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. 21.17, Ayres
Corporation must show that the Ayres Corporation Model LM-200
Loadmaster aircraft meets the applicable provisions of Part 23 as
amended by Amendment 23-1 through 23-53; Part 34 effective September
10, 1990, as amended by the amendment in effect on the date of
certification; Part 36 effective December 1, 1969, as amended by the
amendment in effect on the date of certification; The Noise Control Act
of 1972; exemptions, if any; other special conditions applicable to
this airplane; and the special conditions adopted by this rulemaking
action.
Discussion
If the Administrator finds that the applicable airworthiness
standards (i.e., 14 CFR part 23) do not contain adequate or appropriate
safety standards because of a novel or unusual design feature of an
airplane, special conditions are prescribed under the provisions of
Sec. 21.16. Special conditions, as appropriate, 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. 21.17(a)(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, 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 Ayres Corporation Model LM-200 Loadmaster will 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 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
[[Page 1760]]
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:
------------------------------------------------------------------------
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.
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 the
Ayres Corporation Model LM-200 Loadmaster airplane. Should Ayres
Corporation apply at a later date for a change to the type certificate
to include another model incorporating 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 21.17; 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 the Ayres Corporation Model 200
Loadmaster airplane.
1. Protection of Electrical and Electronic Systems from High
Intensity Radiated Fields (HIRF). Each system 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 December 23, 1999.
Marvin Nuss,
Acting Manager, Small Airplane Directorate Aircraft Certification
Service.
[FR Doc. 00-690 Filed 1-11-00; 8:45 am]
BILLING CODE 4910-13-U
