[Federal Register: September 9, 2003 (Volume 68, Number 174)]
[Rules and Regulations]
[Page 53028-53030]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09se03-5]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM264, Special Conditions No. 25-246-SC]
Special Conditions: Gulfstream Aerospace LP 1125 Westwind Astra;
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 Gulfstream Aerospace
LP 1125 Westwind Astra airplanes modified by Garrett Aviation Services.
These modified airplanes will have novel or unusual design features
when compared to the state of technology envisioned in the
airworthiness standards for transport category airplanes. The
modification incorporates the upgrade of one Air Data Computer system
and the installation of a second Air Data Computer system, both of
which perform critical functions. 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 August 28,
2003. Comments must be received on or before October 9, 2003.
ADDRESSES: Comments on these special conditions may be mailed in
duplicate to: Federal Aviation Administration, Transport Airplane
Directorate, Attention: Rules Docket (ANM-113), Docket No. NM264, 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. NM264.
FOR FURTHER INFORMATION CONTACT: Meghan Gordon, FAA, Standardization
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone
(425) 227-2138; facsimile (425) 227-1149.
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 the airplane 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; 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 close 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 July 2, 2003, Garrett Aviation Services, 1200 North Airport
Drive, Capital Airport, Springfield, IL 62707, applied for a
supplemental type certificate (STC) to modify Gulfstream Aerospace LP
Model 1125 Westwind Astra airplanes approved under Type Certificate No.
A16NM. The Model 1125 Westwind Astra is a small transport category
airplane, powered by two Turbofan Engines; the airplane has a maximum
takeoff weight of 24,800 pounds. The Model 1125 Westwind Astra operates
with a 2-pilot crew and holds up to 9 passengers. The modification
incorporates the upgrade
[[Page 53029]]
of the single Rockwell Collins ADS-85 Air Data System and the
installation of an Innovative Solutions & Support Air Data Display Unit
and a 2-inch Standby Altimeter. These avionics/ electronics and
electrical systems have the potential to be vulnerable to high-
intensity radiated fields (HIRF) external to the airplane.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Garrett Aviation Services
must show that the Model 1125 Westwind Astra airplanes, as modified,
continue 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 Model 1125
Westwind Astra airplanes includes 14 CFR part 25, dated February 1,
1965, through Amendment 25-54, except for special conditions and
exceptions noted in Type Certificate Data Sheet (TCDS) A16NM.
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 Gulfstream Aerospace LP Model 1125
Westwind Astra airplanes modified by Garrett Aviation Services 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 Gulfstream Aerospace LP 1125 Westwind Astra airplanes
modified by Garrett Aviation Services must comply with the fuel vent
and exhaust requirements of 14 CFR part 34 and the noise certification
requirements of 14 CFR part 36, and the FAA must issue a finding of
regulatory adequacy pursuant to Sec. 611 of Public Law 92-574, the
``Noise Control Act of 1972.''
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.
Special conditions are initially applicable to the model for which
they are issued. Should Garrett Aviation Services apply at a later date
for a supplemental type certificate to incorporate the same or similar
novel or unusual design features, these special conditions would also
apply to the other model.
Novel or Unusual Design Features
As noted earlier, the Gulfstream Aerospace LP Model 1125 Westwind
Astra airplanes modified by Garrett Aviation Services will incorporate
the upgrade of the single Rockwell Collins ADS-85 Air Data System and
the installation of an Innovative Solutions & Support Air Data Display
Unit and a 2-inch Standby Altimeter 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, these systems
are considered to be a novel or unusual designs.
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 Aerospace LP Model 1125
Westwind Astra airplanes modified by Garrett Aviation Services. 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 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.
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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
2GHz-4 GHz.............................. 3000 200
4 GHz-6 GHz............................. 3000 200
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6 GHz-8 GHz............................. 1000 200
8 GHz-12 GHz............................ 3000 300
12 GHz-18 GHz........................... 2000 200
18 GHz-40 GHz........................... 600 200
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Note.--The field strengths are expressed in terms of peak of the root-
mean-square (rms) values 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
Gulfstream Aerospace LP Model 1125 Westwind Astra airplanes modified by
Garrett Aviation Services. Should Garrett Aviation Services apply at a
later date for a supplemental type certificate to modify any other
model included on the Type Certificate No. A16NM to incorporate the
same or similar novel or unusual design features, these special
conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on Gulfstream Aerospace LP Model 1125 Westwind Astra airplanes modified
by Garrett Aviation Services. It is not a rule of general applicability
and affects only the applicant which applied to the FAA for approval of
these features on the airplanes.
The substance of these special conditions 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 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 record keeping
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 Gulfstream Aerospace LP Model 1125
Westwind Astra airplanes modified by Garrett Aviation Services.
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.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-22797 Filed 9-8-03; 8:45 am]
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