[Federal Register Volume 61, Number 129 (Wednesday, July 3, 1996)]
[Rules and Regulations]
[Pages 34716-34718]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-16959]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-127; Special Conditions No. 25-ANM-117]


Special Conditions: Cessna Model 500, 550, and S550 Airplanes; 
High-Intensity Radiated Fields

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Cessna Model 500, 
550, and S550 airplanes. These airplanes, as modified by Columbia 
Avionics, Inc., utilize new avionics/electronic systems, such as an 
electronic flight information system (EFIS), which perform critical 
functions. 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 June 20, 1996. 
Comments must be received on or before August 2, 1996.

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-127, 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-127. 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:
Mark Quam, FAA, Standardization Branch, ANM-113, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, Washington, 98055-4056; telephone (206) 227-2145; facsimile 
(206) 227-1149.

SUPPLEMENTARY INFORMATION: 

Comments 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

[[Page 34717]]

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-127.'' The postcard will be date stamped and returned to the 
commenter.

Background

    On April 8, 1996, Columbia Avionics, 11200 Airport Road, Columbia, 
MO 65201, applied for a Supplemental Type Certificate (STC) to modify 
Cessna 500, 550, and S550 airplanes to incorporate the installation of 
an electronic flight instrument system (EFIS). The airplanes are 
pressurized, executive transport airplanes powered by two fuselage-
mounted turbofan engines.

Supplemental Type Certification Basis

    Under the provisions of Sec. 21.101 of 14 CFR part 21, Columbia 
Avionics must show that the modified Cessna 500, 550, and S550 
airplanes continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate A22CE, 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.'' The 
regulations incorporated by reference in TC A22CE include the following 
for the Cessna 500, 550 and S550 series: 14 CFR part 25, dated February 
1, 1965, as amended by Amendments 25-1 through 25-17, and Secs. 25.934 
and 25.1091(d)(2), as amended through Amendment 25-23. In addition, 
under Sec. 21.101(b)(1), the following regulations apply to the EFIS 
installation: Secs. 25.1303, 25.1305, and 25.1322, as amended by 
Amendment 25-38; Secs. 25.1309, 25.1321 (a), (b), (d), and (e), 
25.1331, 25.1333, and 25.1335, as amended by Amendment 25-41; and 
Sec. 25.1316, as amended by Amendment 25-80. These special conditions 
form an additional part of the type certification basis.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., part 25, as amended) do not contain adequate or 
appropriate safety standards for the Cessna Model 500, 550, and S550 
series airplanes because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of Sec. 21.16 to 
establish a level of safety equivalent to that established in the 
regulations.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR Sec. 11.49 after public notice, as required by Secs. 11.28 and 
11.29(b), and become 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 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

    The Cessna Model 500, 550, and S550 airplanes incorporate new 
avionics/electronic systems, such as the electronic flight instrument 
system (EFIS), that perform critical functions. These systems 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.
    To ensure that a level of safety is achieved equivalent to that 
intended by the regulations incorporated by reference, a special 
condition is needed for the Cessna Model 500, 550, and S550, as 
modified by Columbia Avionics, which requires that new electrical and 
electronic systems, such as the EFIS, that perform critical functions 
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 (HIRF)

    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, such as the EFIS, 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.

------------------------------------------------------------------------
                                                       Peak (V/  Average
                      Frequency                           M)      (V/M) 
------------------------------------------------------------------------
10 KHz-100 KHz.......................................       50        50
 100 KHz-500 KHz.....................................       60        60
 500 KHz-2 MHz.......................................       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-1 GHz........................................    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
------------------------------------------------------------------------

    As discussed above, these special conditions are applicable to the 
Cessna Model 500, 550, and S550 airplanes, as modified by Columbia 
Avionics, Inc. Should Columbia Avionics apply at a later date for a 
supplemental type certificate to modify any other model included on 
Type Certificate No. A22CE to incorporate the same novel or unusual 
design feature, this special condition would apply to that model as 
well, under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain design features on the Cessna 
Model 500, 550, and S550 airplanes. It is not a rule of general 
applicability and affects only the applicant who applied to the FAA

[[Page 34718]]

for approval of these features on the airplane.
    The substance of the special conditions for this airplane has been 
subject 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 this special condition 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 Cessna Model 500, 550, and S550 
airplanes, as modified by Columbia Avionics, 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 this special condition, 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, in June 20, 1996.
Gary L. Killion,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 96-16959 Filed 7-2-96; 8:45 am]
BILLING CODE 4910-13-M