[Federal Register Volume 67, Number 116 (Monday, June 17, 2002)]
[Rules and Regulations]
[Pages 41157-41160]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-15196]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM219, Special Conditions No. 25-204-SC]


Special Conditions: Israel Aircraft Industries, Ltd. Model 1124/
1124A Airplanes; 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 for Israel Aircraft 
Industries, Ltd. Model 1124/1124A airplanes modified by Duncan 
Aviation. These airplanes, as

[[Page 41158]]

modified by Duncan Aviation, will have novel and unusual design 
features when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. The 
modification incorporates the installation of a dual Collins AHS-3000A 
Attitude Heading Reference System (AHRS). The applicable airworthiness 
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 provided by the existing 
airworthiness standards.

DATES: The effective date of these special conditions is June 6, 2002. 
Comments must be received on or before July 17, 2002.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attn: Rules Docket (ANM-113), Docket No. NM219, 1601 Lind 
Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate 
to the Transport Airplane Directorate at the above address. All 
comments must be marked: Docket No. NM219. 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: Greg Dunn, FAA, Airplane and Flight 
Crew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington, 98055-4056; telephone (425) 227-2799; facsimile (425) 227-
1149.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice and 
opportunity for prior public comment hereon are impracticable because 
these procedures would significantly delay certification, and thus 
delivery, of the affected airplane. 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; however, the FAA invites interested 
persons to participate in this rulemaking by submitting written 
comments, data, or views. The most helpful comments reference a 
specific portion of the special conditions, explain the reason for any 
recommended change, and include supporting data. We ask that you send 
us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. The docket is available for public 
inspection before and after the comment closing date. If you wish to 
review the docket in person, go to the address in the ADDRESSES section 
of this preamble between 7:30 a.m. and 4 p.m., Monday through Friday, 
except Federal holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions in light of the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

Background

    On March 28, 2002, Duncan Aviation, Inc., P.O. Box 81887, Lincoln, 
NE 68501, applied for a supplemental type certificate (STC) to modify 
Israel Aircraft Industries Ltd. Model 1124/1124A airplanes approved 
under Type Certificate No. A2SW. The Israel Aircraft Industries, Ltd. 
1124/1124A airplanes are executive type transports that have two aft 
mounted turbine engines, a maximum passenger load of 10 passengers, and 
a maximum operating speed of 360 knots. The modification incorporates 
the installation of a dual Collins AHS-3000A Attitude Heading Reference 
System (AHRS). The AHS-3000A is a solid state, strap-down attitude/
heading reference system using quartz based inertial sensor technology. 
Its primary function is to provide measurements of the airplane's 
pitch, roll, and heading for use by cockpit displays, flight control 
and management systems, and other avionics equipment. The basic AHS-
3000A system consists of a Collins AHC-3000A Attitude/Heading Computer, 
a Collins FDU-3000 Flux Detector, and a Collins ECU-3000 External 
Compensation Unit. These advanced systems use electronics to a far 
greater extent than the original inertial navigation systems and may be 
more susceptible to electrical and magnetic interference caused by 
high-intensity radiated fields (HIRF). This disruption of signals could 
result in loss of attitude or the display of misleading information to 
the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Duncan Aviation, Inc. must 
show that the Israel Aircraft Industries, Ltd. Model 1124/1124A 
airplanes, as changed, continue to meet the applicable provisions of 
the regulations incorporated by reference in Type Certificate No. A2SW, 
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 certification basis for the modified Israel 
Aircraft Industries, Ltd. Model 1124/1124A airplanes includes Civil Air 
Regulations (CAR) 4b, effective December 31, 1953, including amendments 
through amendment level 4b-11. Other applicable amendments, Federal 
Aviation Regulations, and special conditions are noted in Type 
Certificate Data Sheet (TCDS) A2SW.
    If the Administrator finds that the applicable airworthiness 
regulations (that is, CAR 4b or 14 CFR part 25, as amended) do not 
contain adequate or appropriate safety standards for the Israel 
Aircraft Industries, Ltd. Model 1124/1124A airplanes because of novel 
or unusual design features, special conditions are prescribed under the 
provisions of Sec. 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Israel Aircraft Industries, Ltd. Model 1124/1124A 
airplanes must comply with the fuel vent and exhaust emission 
requirement of 14 CFR part 34 and the noise certification requirement 
of part 36.
    Special conditions, as defined in 14 CFR 11.19, are issued in 
accordance with Sec. 11.38, 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 Duncan Aviation, Inc. apply at a later date 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 features, these special conditions would also apply to 
the other model under the provisions of 14 CFR 21.101(a)(1).

Novel or Unusual Design Features

    The Israel Aircraft Industries, Ltd. Model 1124/1124A airplanes 
will incorporate a dual Collins AHS-3000A Attitude Heading Reference 
System, which performs critical functions. Each system consists of a 
Collins AHC-3000A Attitude/Heading Computer, a Collins

[[Page 41159]]

FDU-3000 Flux Detector Unit, and a Collins ECU-3000 External 
Compensation Unit. Because these advanced systems use electronics to a 
far greater extent than the original inertial navigation systems, they 
may be more susceptible to electrical and magnetic interference caused 
by high-intensity radiated fields (HIRF) external to the airplane. The 
current airworthiness standards (14 CFR part 25) do not contain 
adequate or appropriate safety standards that address protecting this 
equipment from the adverse effects of HIRF. Accordingly, these 
instruments are considered to be a novel or unusual design feature.

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 avionics/electronics and electrical 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 Israel Aircraft Industries, Ltd. Model 
1124/1124A airplanes modified to include the new navigation system. 
These special conditions will require that the new Collins Avionics 
AHS-3000A Attitude Heading Reference Systems, which 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/electronics and electrical 
systems 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 in accordance with either paragraph 1 or 2 below:
    1. A minimum threat of 100 volts rms (root-mean-square) per meter 
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 field strengths 
indicated in the table below for the frequency ranges indicated. Both 
peak and average field strength components from the table below are to 
be demonstrated.

------------------------------------------------------------------------
                                                  Field Strength (volts
                                                       per meter)
                   Frequency                   -------------------------
                                                    Peak       Average
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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 of the root-mean
square (rms) over the complete modulation period.
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    The threat levels identified above are the result of an FAA review 
of existing studies on the subject of HIRF, in light of the ongoing 
work of the Electromagnetic Effects Harmonization Working Group of the 
Aviation Rulemaking Advisory Committee.

Applicability

    As discussed above, these special conditions are applicable to 
Israel Aircraft Industries, Ltd. Model 1124/1124A airplanes modified by 
Duncan Aviation, Inc. to include the Collins AHS-3000A Attitude Heading 
Reference Systems. Should Duncan Aviation, Inc. apply at a later date 
for a supplemental type certificate to modify any other model already 
included on Type Certificate A2SW to incorporate the same novel or 
unusual design features, these special conditions would apply to that 
model as well under the provisions of 14 CFR 21.101(a)(1).

Conclusion

    This action affects only certain design features on Israel Aircraft 
Industries, Ltd. Model 1124/1124A airplanes modified by Duncan 
Aviation, Inc. 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 the special conditions for this airplane has been 
subjected to notice and comment procedure in several prior instances 
and has been derived without substantive change from those previously 
issued. 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 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions 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 supplemental type certification basis for Israel Aircraft 
Industries, Ltd. Model 1124/1124A airplanes modified by Duncan 
Aviation, 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 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.


[[Page 41160]]


    Issued in Renton, Washington, on June 6, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 02-15196 Filed 6-14-02; 8:45 am]
BILLING CODE 4910-13-P