[Federal Register Volume 67, Number 101 (Friday, May 24, 2002)]
[Rules and Regulations]
[Pages 36502-36504]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-13131]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE184; Special Condition 23-118-SC]


Special Conditions; Avidyne Corporation on the Cirrus Design 
Corporation Model SR20/SR22; 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 Avidyne Corporation, 55 
Old Bedford Road, Lincoln, Massachusetts, 01773 for a Supplemental Type 
Certificate for the Cirrus Design Corporation SR20/SR22 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 an electronic flight instrument system (EFIS) display 
Model 700-00006-XXX-( ) manufactured by Avidyne Corporation 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 this airplane.

DATES: The effective date of these special conditions is May 7, 2002. 
Comments must be received on or before June 24, 2002.

ADDRESSES: Comments may be mailed in duplicate to: Federal Aviation 
Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk, 
Docket No. CE184, Room 506, 901 Locust, Kansas City, Missouri 64106. 
All comments must be marked: Docket No. CE184. Comments may be 
inspected in the Rules Docket weekdays, except Federal holidays, 
between 7:30 a.m. and 4 p.m.

[[Page 36503]]


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.

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 action must include a self-
addressed, stamped postcard on which the following statement is made: 
``Comments to Docket No. CE184.'' The postcard will be date stamped and 
returned to the commenter.

Background

    On April 20, 2001, Avidyne Corporation, 55 Old Bedford Road, 
Lincoln, Massachusetts, 01773, made an application to the FAA for a new 
Supplemental Type Certificate for the Cirrus Design Corporation Models 
SR20/SR22 airplanes. The Cirrus SR20/SR22 are currently approved under 
TC No. A00009CH. 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, [sect] 21.101, Avidyne 
Corporation must show that the Cirrus SR20/SR22 aircraft meet the 
following provisions, or the applicable regulations in effect on the 
date of application for the change to the Cirrus SR20/SR22.
    Model SR20: Part 23 of the Federal Aviation Regulations effective 
February 1, 1965, as amended by 23-1 through 23-47, except as follows: 
14 CFR part 23, [sect][sect] 23.573, 23.575, 23.611, 23.657, 23.673 
through Amendment 23-48; 14 CFR [sect][sect] 23.783, 23.785, 23.867, 
23.1303, 23.1307, 23.1309, 23.1311, 23.1321, 23.1323, 23.1329, 23,1361, 
23.1383, 23.1401, 23.1431, 23.1435 through Amendment 23-49; 14 CFR part 
23, [sect][sect] 23.3, 23.25, 23.143, 23.145, 23.155, 23.1325, 23.1521, 
23.1543, 23.1555, 23.1559, 23.1567, 23.1583, 23.1585, 23.1589 through 
Amendment 23-50; 14 CFR part 23, [sect][sect] 23.777, 23.779, 23.901, 
23.907, 23.955, 23.959, 23.963, 23.965, 23.973, 23.975, 23.1041, 
23.1091, 23.1093, 23.1107, 23.1121, 23.1141, 23.1143, 23.1181, 23.1191, 
23.1337 through Amendment 23-51; 14 CFR part 23, [sect] 23.1305 through 
Amendment 23-52.
    Model SR22: Part 23 of the Federal Aviation Regulations effective 
February 1, 1965, as amended by 23-1 through 23-53, except as follows: 
[sect] 23.301 through Amendment 47; [sect][sect] 23.855, 23.1326, 
23.1359, not applicable. 14 CFR part 36 dated December 1, 1969, as 
amended by current amendment as of the date of type certification.
    Equivalent Levels of Safety finding (ACE-96-5) made per the 
provisions of 14 CFR part 23, [sect] 23.221; Refer to FAA ELOS letter 
dated June 10, 1998 for models SR20, SR22. Equivalent Levels of Safety 
finding (ACE-00-09) made per the provisions of 14 CFR part 23, 
[sect][sect] 23.1143(g) and 23.1147(b); Refer to FAA ELOS letter dated 
September 11, 2000, for model SR22. Equivalent Levels of Safety finding 
(ACE-01-01) made per the provisions of 14 CFR part 23, [sect][sect] 
23.1143(g) and 23.1147(b); Refer to FAA ELOS letter dated February 14, 
2000, for model SR20.
    Special Condition (23-ACE-88) for ballistic parachute; Refer to FAA 
letter November 25, 1997, for models SR20, SR22.

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 [sect] 21.16.
    Special conditions, as appropriate, as defined in [sect] 11.19, are 
issued in accordance with [sect] 11.38 after public notice and become 
part of the type certification basis in accordance with 14 CFR part 21 
[sect] 21.101.
    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 [sect] 21.101.

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 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.

[[Page 36504]]

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 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 over the complete modulation period.

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 rms per meter, 
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 
Cirrus Design Corporation SR20/SR22 airplanes. Should Avidyne 
Corporation 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 [sect] 21.101.

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, 
[sect] 21.16 and [sect] 21.101; and 14 CFR 11.38 and 11.19.

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 Cirrus Design Corporation SR20/SR22 
airplanes modified by Avidyne Corporation to add an EFIS.
    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 May 7, 2002.
Dorenda D. Baker,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-13131 Filed 5-23-02; 8:45 am]
BILLING CODE 4910-13-P