[Federal Register Volume 60, Number 38 (Monday, February 27, 1995)]
[Rules and Regulations]
[Pages 10482-10483]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-4772]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 25

[Docket No. NM-107; Special Conditions No. 25-ANM-95]


Special Conditions; Modified Cessna 550 Series Airplanes; High 
Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions with request for comments.

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SUMMARY: These special conditions are issued for Cessna 550 series 
airplanes modified by Elliott Aviation Technical Products Development, 
Inc. of Moline Illinois. These airplanes are equipped with digital 
head-up display (HUD) systems that perform critical functions. The 
applicable type certification 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 provide the additional safety standards that the 
Administrator considers necessary to ensure that the critical functions 
that these systems perform are maintained when the airplane is exposed 
to HIRF.

DATES: The effective date of these special conditions is February 13, 
1995. Comments must be received on or before April 13, 1995.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate (ANM-100), Attn: Docket No. NM-107, 1601 Lind Avenue SW., 
Renton, WA 98055-4056; or delivered in duplicate to the Transport 
Airplane Directorate at the above address. Comments must be marked: 
Docket No. NM-107. 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:
Michael Zielinski, FAA, Standardization Branch, ANM-113, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, WA 98055-4056; telephone (206) 227-2279.

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 regulatory docket or 
special conditions 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 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-107.'' The postcard will be date 
stamped and returned to the commenter.

Background

    On October 25, 1994, Elliott Aviation Technical Products 
Development, Inc. of Moline, Illinois, applied for a supplemental type 
certificate to modify Cessna 550 series airplanes. The Cessna 550 is a 
business jet with two aft-mounted turbofan engines. The airplane can 
carry two pilots and up to 11 passengers, depending on the exit and 
interior configuration, and is capable of operating to an altitude of 
43,000 feet. The proposed modification incorporates the installation of 
digital avionics consisting of a head-up display (HUD) system that is 
potentially vulnerable to HIRF external to the airplane.

Supplemental Type Certification Basis

    Under the provisions of Sec. 21.101 of the FAR, Elliott Aviation 
Technical Products Development, Inc. must show that the modified Cessna 
550 series airplanes continue to meet the applicable provisions of the 
regulations incorporated by reference in Type Certificate No. 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 Type Certificate No. 
A22CE include the following: Part 25 of the Federal Aviation 
Regulations (FAR), dated February 1, 1965, including Amendments 25-1 
through 25-17. In addition the following sections of the FAR apply to 
the HUD installation: Secs. 25.1303(b) and 25.1322, as amended through 
Amendment 25-38; Secs. 25.1309, 25.1321 (a), (b), (d), and (e), 
25.1333, and 25.1335, as amended by Amendment 25-41. These special 
conditions will form an additional part of the supplemental 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 550 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 
Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28 
and 11.29, 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 [[Page 10483]] 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).

Discussion

    There is no specific regulation that address 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, special 
conditions are needed for the Cessna 550 series airplanes that would 
require that new technology electrical and electronic systems, such as 
the HUD, 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 HUD, 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(V/
                     Frequency                         M)         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-70 MHz.....................................        30         30 
70 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 
Cessna 550 series airplanes, modified by Elliott Aviation Technical 
Products Development, Inc. Should Elliott Aviation Technical Products 
Development, Inc. 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, 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 unusual or novel design features 
on Cessna 550 series airplanes modified by Elliott Aviation Technical 
Products Development, Inc. of Moline, Illinois. It is not a rule of 
general applicability and affects only the applicant who applied to the 
FAA for approval of these features on modified Cessna 550 series 
airplanes.
    The substance of the special conditions for these airplanes has 
been subjected 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 have not 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 these special conditions is as follows:

    Authority: 49 U.S.C. app. 1344, 1348(c), 1352, 1354(a), 1355, 
1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et 
seq.; E.O. 11514; and 49 U.S.C. 106(g).

The Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special condition is issued as part of the 
supplemental type certification basis for Cessna 550 series airplanes 
modified by Elliott Aviation Technical Products Development, 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 external to the airplane.
    2. The following definition applies with respect to this special 
condition: 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, on February 13, 1995.
Darrell M. Pederson,
Assistant Manager, Transport Airplane Directorate, Aircraft 
Certification Service, ANM-101.
[FR Doc. 95-4772 Filed 2-24-95; 8:45 am]
BILLING CODE 4910-13-M