[Federal Register Volume 70, Number 109 (Wednesday, June 8, 2005)]
[Rules and Regulations]
[Pages 33337-33338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-11409]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM308, Special Conditions No. 25-289-SC]


Special Conditions: Gulfstream Model LP 1125 Westwind Astra 
Airplane; 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 the Gulfstream Model 
LP 1125 Westwind Astra airplane modified by Duncan Aviation, Inc. This 
airplane will have novel and unusual design features when compared to 
the state of technology envisioned in the airworthiness standards for 
transport category airplanes. 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 May 19, 2005.
    Comments must be received on or before July 8, 2005.

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. NM308, 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. NM308.

FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Standardization 
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-2011; facsimile (425) 227-1320.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment is impracticable because these procedures would significantly 
delay certification of and delivery of the affected airplanes. 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 based on the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on 
these special conditions, 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 February 16, 2005, Duncan Aviation, Inc., Lincoln, Nebraska, 
applied to the Wichita Aircraft Certification Office, for a 
supplemental type certificate (STC) to modify certain Gulfstream Model 
LP 1125 Westwind Astra airplanes to include the installation of 
integrated display systems (electronic displays and electronic engine 
controls). These integrated display systems installed in this airplane 
have the potential to be vulnerable to HIRF external to the airplane. 
The subject Gulfstream Model LP 1125 Westwind Astra airplane is a small 
business jet powered by two Honeywell (formerly Allied Signal and 
Garrett) TFE 731-3A-200G or TFE 731-3C-200G engines. This airplane 
operates with a 2-person crew and holds nine passengers.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Duncan Aviation, Inc. must 
show that the Gulfstream Model LP 1125 Westwind Astra airplane, as 
changed, continues to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A16NM, 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 Gulfstream Model LP 
Westwind Astra airplane includes 14 CFR part 25 effective February 1, 
1965, as amended by Amendments 25-1 through 25-54. In addition, the 
certification basis includes certain special conditions, exemptions, 
and equivalent levels of safety that are not relevant to these special 
conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (part 25, as amended) do not contain adequate or 
appropriate safety standards for the Gulfstream Model LP 1125 Westwind 
Astra airplane, modified by Duncan Aviation, Inc., because of a novel 
or unusual design feature, special conditions are prescribed under the 
provisions of 14 CFR 21.16. In addition to the applicable airworthiness 
regulations and special conditions, the Gulfstream Model LP 1125 
Westwind Astra airplane must comply with the fuel vent and exhaust 
emission requirements of 14 CFR part 34 and the noise certification 
requirements of 14 CFR part 36.
    Special conditions, as defined in 14 CFR 11.19, are issued in 
accordance with Sec.  11.38, and become part of the airplane's type 
certification basis in accordance with Sec.  21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should Duncan Aviation, Inc. apply at a later date for 
an STC to modify any other model included on the same type certificate 
to incorporate the same or similar novel or unusual design feature, 
these special conditions would also apply to the other model under the 
provisions of Sec.  21.101.

Novel or Unusual Design Features

    The modified Gulfstream LP 1125 Westwind Astra airplane will 
incorporate integrated display systems

[[Page 33338]]

(electronic displays and electronic engine controls) that will perform 
critical functions. These systems may be vulnerable to HIRF external to 
the airplane. The current airworthiness standards of part 25 do not 
contain adequate or appropriate safety standards for the protection of 
this equipment from the adverse effects of HIRF. Accordingly, this 
system is 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 Gulfstream Model LP 1125 Westwind Astra 
airplane. These special conditions require that new avionics/
electronics and electrical systems 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, and 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 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 
identified in the table below for the frequency ranges indicated. Both 
peak and average field strength components from the table are to be 
demonstrated.

------------------------------------------------------------------------
                                                       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
2GHz-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.

    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 the 
Gulfstream Model LP 1125 Westwind Astra airplane. Should Duncan 
Aviation, Inc., apply at a later date for an STC to modify any other 
model included on Type Certificate No. A16NM to incorporate the same or 
similar novel or unusual design feature, these special conditions would 
apply to that model as well as under the provisions of Sec.  21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on the Gulfstream Model LP 1125 Westwind Astra 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 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. 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. 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 the Gulfstream Model LP 
1125 Westwind Astra airplane 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.

    Issued in Renton, Washington, on May 19, 2005.
Mike Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-11409 Filed 6-7-05; 8:45 am]
BILLING CODE 4910-13-P