[Federal Register Volume 63, Number 198 (Wednesday, October 14, 1998)]
[Rules and Regulations]
[Pages 55012-55015]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-27533]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE148, Special Condition 23-98-04-SC]


Special Conditions; Raytheon Aircraft Company Model 300 Airplane; 
Protection of Systems for High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued to California Microwave, 
Inc., 701 Wilson Point Road, Martin State Airport, Box 4, Baltimore, 
Maryland 21220, for a Supplemental Type Certificate on the Raytheon 
Model 300 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

[[Page 55013]]

and unusual design features include the installation of an electronic 
flight instrument system (EFIS) 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 October 2, 
1998. Comments must be received on or before November 13, 1998.

ADDRESSES: Comments may be mailed in duplicate to: Federal Aviation 
Administration, Regional Counsel, ACE-7, Attention: Rules Docket Clerk, 
Docket No. CE148, Room 1558, 601 East 12th Street, Kansas City, 
Missouri 64106. All comments must be marked: Docket No. CE148. 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 Docket No. CE148.'' The postcard will be date stamped and 
returned to the commenter.

Background

    On April 23, 1998, California Microwave, Inc., 701 Wilson Point 
Road, Martin State Airport, Box 4, Baltimore, Maryland 21220, applied 
to the FAA for a Supplemental Type Certificate (STC) for a modification 
on a Raytheon Model 300 airplane. 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 21.101, California Microwave, Inc. 
must show that the Raytheon Model 300 airplane meets the applicable 
provisions of the following:
    The type certification basis as modified by this STC to add an EFIS 
on the Raytheon Model 300 airplane is given by the following:
    Special Federal Aviation Regulation (SFAR) 41C, effective September 
13, 1982, see NOTE 7 or 11 (300 only); 14 CFR part 23, effective 
February 1, 1965, through Amendment 23-9; Amendment 23-11; Amendment 
23-14, Secs. 23.143(a). 23.145(d), 23.153, 23.161(c)(3), 23.173(a), 
23.175, 23.427, 23.441, and 23.445; Amendment 23-15, Sec. 23.951(c) and 
Sec. 23.997(d); Amendment 23-23, Sec. 23.1545(a); Amendment 23-26, 
Secs. 23.967 and 23.1305(n); Special Conditions No. 23-47-CE-5, 
including Amendment Nos.. 1, 2, 3 dated November 15, 1982, and 4 dated 
October 17, 1986; 14 CFR part 25, Sec. 25.929, effective February 1, 
1965, Amendment 25-23, Sec. 25.1419; Amendment 25-41, Sec. 25.831(d); 
14 CFR part 36, through Amendment 36-10, and SFAR 27, through Amendment 
27-4; Sec. 23.1301 of Amendment 23-20; Secs. 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. Compliance with ice protection has been demonstrated 
in accordance with Sec. 25.1419 when ice protection equipment is 
installed in accordance with the Equipment List.
    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 300 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. 21.101(b)(2).
    Special conditions are initially applicable to the model for which 
they 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).

Novel or Unusual Design Features

    The California Microwave, Inc. modified Raytheon Model 300 airplane 
will incorporate the following novel or unusual design features: 
Installation of an EFIS for which the airworthiness standards do not 
contain adequate or appropriate safety standards for protection from 
the effects of HIRF.

Discussion

    The FAA may issue and amend special conditions, as necessary, as 
part of the type certification basis if the Administrator finds that 
the airworthiness standards, designated according to Sec. 21.101(b), 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 to establish a level of 
safety equivalent to that established in the regulations. Special 
conditions are normally issued according to Sec. 11.49, after public 
notice, as required by Secs. 11.28 and 11.29(b), effective October 14, 
1980, and become a part of the type certification basis in accordance 
with Sec. 21.101(b)(2).
    California Microwave, 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 an EFIS, 
which is susceptible to the HIRF environment, that was not envisaged by 
the existing regulations for this type of airplane.

[[Page 55014]]

Protection of Systems From High Intensity Radiated Fields (HIRF)

    Recent advances in technology have given rise to the application in 
aircraft designs of advanced EFIS 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 EFIS 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 EFIS 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 EFIS 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 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, 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 EFIS, 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 300 airplane. Should California Microwave, Inc. apply at 
a later date for a supplemental type certificate to modify any other 
model included on the same type certificate incorporating, 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 Raytheon Model 300 airplane. It is not a rule of general 
applicability and

[[Page 55015]]

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 21.16 and 
21.101; and 14 CFR 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 Raytheon Model 300 airplane modified 
by California Microwave, Inc. 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 operation, 
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 October 2, 1998.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-27533 Filed 10-13-98; 8:45 am]
BILLING CODE 4910-13-P