[Federal Register Volume 71, Number 139 (Thursday, July 20, 2006)]
[Rules and Regulations]
[Pages 41099-41101]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-11483]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE194, Special Condition 23-134A-SC]


Special Conditions; Cirrus Design Corporation SR22; Protection of 
Systems for High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Amended final special conditions; request for comments.

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SUMMARY: These amended special conditions are issued to Cirrus Design 
Corporation, 4515 Taylor Circle, Duluth, Minnesota 55811, for a Type 
Design Change. This special condition amends special condition 23-134-
SC, which was published February 4, 2003 (68FR 5538), for installation 
of an Electronic Flight Instrument System (EFIS) manufactured by 
Avidyne Corporation on the SR22. This amendment covers additional 
electronic equipment, such as a digital autopilot and/or engine related 
systems designed to perform critical functions on the SR22 and other 
models listed on the same Type Data Sheet, A00009CH.
    The airplanes will have novel and unusual design features when 
compared to the state of technology envisaged in the applicable 
airworthiness standards. 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 July 11, 2006.
Comments must be received on or before August 21, 2006.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate

[[Page 41100]]

to: Federal Aviation Administration, Regional Counsel, ACE-7, 
Attention: Rules Docket Clerk, Docket No. CE194, Room 506, 901 Locust, 
Kansas City, Missouri 64106. All comments must be marked: Docket No. 
CE194. 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: Wes Ryan, 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) 329-4113.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable because 
these procedures have been subject to the public comment process 
several times in the past without substantive comment. 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. CE194.'' The postcard will be date stamped and 
returned to the commenter.

Background

    In February 2005, Cirrus Design Corporation, 4515 Taylor Circle, 
Duluth, Minnesota 55811 made application to the FAA for a change in 
Type Design for the SR22 airplane model listed on Type Data Sheet 
A00009CH. The proposed modification incorporates novel or unusual 
design features that are potentially vulnerable to HIRF external to the 
airplane.

Type Certification Basis

    Under the provisions of 14 CFR part 21, Sec.  21.101, Cirrus Design 
Corporation must show that affected airplane models, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference on Type Data Sheet A00009CH, 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 
certification basis.'' In addition, the type certification basis of 
airplane models that embody this modification will include Sec.  
23.1301 of Amendment 23-20; Sec. Sec.  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, as appropriate, as defined in Sec.  11.19, are 
issued in accordance with Sec.  11.38 after public notice and become 
part of the type certification basis in accordance with Sec.  
21.101(b)(2) of Amendment 21-69.
    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.

Novel or Unusual Design Features

    Cirrus Design Corporation 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. 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:

[[Page 41101]]



------------------------------------------------------------------------
                                                       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.

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, 
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 one 
modification to the airplane models listed under the heading ``Type 
Certification Basis.'' Should Cirrus Design 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 Sec.  21.101.

Conclusion

    This action affects only certain novel or unusual design features 
of one modification to several models of 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 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 some airplane 
models, 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 21.16 and 
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 airplane models listed under the 
``Type Certification Basis'' heading modified by Cirrus Design 
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 July 11, 2006.
Steve W. Thompson,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-11483 Filed 7-19-06; 8:45 am]
BILLING CODE 4910-13-P