[Federal Register Volume 66, Number 87 (Friday, May 4, 2001)]
[Rules and Regulations]
[Pages 22426-22428]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-11254]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM190, Special Conditions No. 25-178-SC]


Special Conditions: Bombardier Inc. Model CL-600-1A11 Airplane; 
High-Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for Bombardier Inc. Model 
CL-600-1A11 airplanes modified by Duncan Aviation, Inc. These modified 
airplanes 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 dual Attitude Heading Reference Systems (AHRS) as well 
as a new Electronic Flight Information System (EFIS) that displays 
critical flight parameters to the flightcrew. The applicable 
airworthiness standards do not contain adequate or appropriate safety 
standards for the protection of these systems from the effects of high-
intensity radiated fields. The 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 April 25, 
2001.
    Comments must be received on or before June 4, 2001.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attn: Rules Docket (ANM-114), Docket No. NM190, 1601 Lind 
Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate 
to the Transport Airplane Directorate at the above address. Comments 
must be marked: Docket No. NM190. 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 (425) 227-2145; facsimile (425) 227-1149.

[[Page 22427]]


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 
rules 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 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 these special conditions must include 
a self-addressed, stamped postcard on which the following statement is 
made: ``Comments to Docket No. NM190.'' The postcard will be date 
stamped and returned to the commenter.

Background

    On November 28, 2000, Duncan Aviation Inc., P.O. Box 81887, 
Lincoln, NE 68501, applied for a supplemental type certificate (STC) to 
modify Bombardier Inc. Model CL-600-1A11 airplane listed on Type 
Certificate A21EA. The Model CL-600-1A11 is a twin engine transport 
airplane. It has an executive interior and is capable of carrying two 
flight crewmembers and up to nineteen passengers. This model is powered 
by two aft mounted AVCO Lycoming ALF-502L or ALF-502L-2 engines. The 
modification incorporates the installation of dual Rockwell Collins 
Attitude Heading Reference Systems (AHRS) as well as a new Electronic 
Flight Information System (EFIS) that displays critical flight 
parameters to the flightcrew. These systems can be susceptible to 
disruption to command and/or response signals as a result of electrical 
and magnetic interference. This disruption of signals could result in 
loss of all critical flight displays and annunciations or present 
misleading information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Duncan Aviation must show 
that the Bombardier Inc. Model CL-600-1A11 airplanes, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A21EA, 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 
Bombardier Inc. Model CL-600-1A11 airplane includes 14 CFR part 25, 
dated February 1, 1965, including Amendments 25-1 through 25-37, as 
listed in the Type Certificate Data Sheet (TCDS) A21EA.
    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 Bombardier Inc. Model CL-600-1A11 
airplane because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of Sec. 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model CL-600-1A11 airplane must comply with the part 25 
fuel vent and exhaust emission requirements of 14 CFR part 34 and the 
part 25 noise certification requirements of 14 CFR part 36.
    Special conditions, as defined in Sec. 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 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, 
these special conditions would also apply to the other model under the 
provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The Bombardier Inc. Model CL-600-1A11 airplane will incorporate the 
following novel or unusual design features: Dual Attitude and Heading 
Reference Systems (AHRS) as well as a new Electronic Flight Information 
System (EFIS) that displays critical flight parameters to the 
flightcrew. These systems can be susceptible to disruption to command 
and/or response signals as a result of electrical and magnetic 
interference. This disruption of signals could result in loss of all 
critical flight displays and annunciations or present misleading 
information to the pilot.

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 avionic/electronic 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 Bombardier Inc. Model CL-600-1A11 as 
modified by Duncan Aviation Inc. These special conditions require that 
new avionic/electronic and electrical systems, such as the AHRS and 
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 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 paragraph 1, or paragraph 2, below:
    1. A minimum threat of 100 volts rms 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.

[[Page 22428]]

    2. A threat external to the airframe of the following field 
strengths for the frequency ranges indicated. Both peak and average 
field strength components from the Table are to be demonstrated.

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                                             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 
Bombardier Inc. Model CL-600-1A11 airplane modified by Duncan Aviation, 
Inc. Should Duncan apply at a later date 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, 
these 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 Bombardier Inc. Model CL-600-1A11 airplane 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 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 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 type certification basis for Bombardier Inc. Model CL-600-1A11 
airplanes modified by Duncan.
    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.

    Issued in Renton, Washington, on April 25, 2001.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-11254 Filed 5-3-01; 8:45 am]
BILLING CODE 4910-13-U