[Federal Register Volume 63, Number 248 (Monday, December 28, 1998)]
[Rules and Regulations]
[Pages 71369-71371]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-34162]



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 Rules and Regulations
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  Federal Register / Vol. 63, No. 248 / Monday, December 28, 1998 / 
Rules and Regulations  

[[Page 71369]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE150, Special Condition 23-094-SC]


Special Conditions; Raytheon Aircraft Company, Raytheon Model 390 
Airplane: Protection of Systems From 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 Raytheon Aircraft 
Company, 9709 East Central, Wichita, Kansas 67201-0085 for a type 
certificate on the Raytheon Model 390 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 systems (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 that provided by the applicable airworthiness standards.

DATES: The effective date of these special conditions is December 28, 
1998. Comments must be received on or before January 27, 1999.

ADDRESSES: Comments may be mailed in duplicate to: Federal Aviation 
Administration, Office of the Assistant Chief Counsel, ACE-7, 
Attention: Rules Docket Clerk, Docket No. CE150, Room 1558, 601 East 
12th Street, Kansas City, Missouri 64106. All comments must be marked: 
Docket No. CE150. 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, 601 East 12th 
Street, Kansas City, Missouri 64106; telephone (816) 426-6941.

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 CE150.'' The postcard will be date stamped and returned 
to the commenter.

Background

    On August 1, 1995, Raytheon Aircraft Company (then Beech Aircraft 
Corporation) made application to the FAA for a type certificate for the 
Raytheon Model 390 airplane. The proposed configuration 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, Raytheon 
Aircraft Company must show that the Raytheon Model 390 meets the 
applicable provisions of the following type certification basis for the 
Raytheon Model 390 airplane:
    Federal Aviation Regulations part 23 effective February 1, 1965, as 
amended by Amendments 23-1 through 23-52, with Special Conditions to 
replace much of Subparts B and G; Federal Aviation Regulations part 34 
effective September 10, 1990, as amended by the amendment in effect on 
the date of certification; Federal Aviation Regulations part 36 
effective December 1, 1969, as amended by amendment 36-1 through the 
amendment in effect on the day of certification; The Noise Control Act 
of 1972; Special Conditions for such items as Protection from High 
Intensity Radiated Fields (HIRF), Takeoff Out of Trim Warning, and 
Engine Fire Extinguishing System; and Exemption No. 6558, which was 
granted December 12, 1996, pertaining to airplane landing gear loads.

Novel or Unusual Design Features

    The Raytheon Model 390 will incorporate the following novel or 
unusual design features: Installation of EFIS for which the 
airworthiness standards do not contain adequate or appropriate safety 
standards for protection from the effects of HIRF.

Discussion

    If the Administrator finds that the applicable airworthiness 
regulations, 14 CFR part 23, do not contain adequate or appropriate 
safety standards for the Raytheon Model 390 because of a novel or 
unusual design feature, special conditions are prescribed under the 
provisions of Sec. 21.16.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49, as required by Secs. 11.28 and 11.29(b), and become 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

[[Page 71370]]

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).
    Raytheon Aircraft Company 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 electronic 
systems, 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 previously 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 as follows:

                       Field Strength Volts/Meter
------------------------------------------------------------------------
                      Frequency                         Peak    Average
------------------------------------------------------------------------
10-100 KHz..........................................       50         50
100-500 KHz.........................................       60         60
500-2000 KHz........................................       70         70
2-30 MHz............................................      200        200
30-70 MHz...........................................       30         30
70-100 MHz..........................................       30         30
100-200 MHz.........................................      150         33
200-400 MHz.........................................       70         70
400-700 MHz.........................................     4020        935
700-1000 MHz........................................     1700        170
1-2 GHz.............................................     5000        990
2-4 GHz.............................................     6680        840
4-6 GHz.............................................     6850        310
6-8 GHz.............................................     3600        670
8-12 GHz............................................     3500       1270
12-18 GHz...........................................     3500        360
18-40 GHz...........................................     2100        750
------------------------------------------------------------------------

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 electrical and/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 
Raytheon Model 390. Should Raytheon Aircraft Company apply at a later 
date for a supplemental type certificate or amended type certificate to 
modify any other model that may be included on this 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(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

[[Page 71371]]

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 Raytheon Aircraft Company Model 
390 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 11, 1998.
Michael K. Dahl,
Acting Manager, Small Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 98-34162 Filed 12-24-98; 8:45 am]
BILLING CODE 4910-13-P