[Federal Register: December 9, 2003 (Volume 68, Number 236)]
[Rules and Regulations]
[Page 68501-68503]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09de03-5]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM271, Special Conditions No. 25-254-SC]
Special Conditions: Boeing Model 707-300 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 Boeing Model 707-300
airplanes modified by AeroMech Incorporated. 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 Innovative Solutions and Support Air Data Display Units. 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 December 1,
2003.
Comments must be received on or before January 8, 2004.
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. NM271, 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. NM271.
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-
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 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 closing date. If you wish to
review the docket in person, go to the address in the ADDRESSES section
of this preamble
[[Page 68502]]
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 August 29, 2003, AeroMech Incorporated applied to the FAA, Fort
Worth Special Certification Office, for a supplemental type certificate
(STC) to modify certain Boeing Model 707-300 airplanes. These models
are currently approved under Type Certificate No. 4A26. The Model 707-
300 is a transport category airplane powered by four Pratt & Whitney
turbojet engines. This airplane operates with three flightcrew and can
hold up to 189 passengers. The modification incorporates the
installation of dual Innovative Solutions and Support (IS&S) Air Data
Display Units. The information presented is flight critical. The
avionics/electronics and electrical systems installed in this airplane
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, AeroMech Incorporated must
show that the Boeing Model 707-300 airplanes, as changed, continue to
meet the applicable provisions of the regulations incorporated by
reference in Type Certificate No. 4A26, 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 707-300 airplanes includes Civil Air Regulations
(CAR) 4b, as amended by Amendments 4b-1, 4b-2, and 4b-3; and additional
requirements identified in the type certificate data sheet that are not
relevant to these special conditions.
If the Administrator finds that the applicable airworthiness
regulations (CAR 4b, as amended) do not contain adequate or appropriate
safety standards for the Boeing Model 707-300 airplanes 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 Boeing Model 707-300 airplanes 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 type certification
basis in accordance with Sec. 21.101.
Special conditions are initially applicable to the model for which
they are issued. Should AeroMech Incorporated apply at a later date for
a supplemental type certificate to modify any other model included on
Type Certificate 4A26 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
As noted earlier, Boeing Model 707-300 airplanes modified by
AeroMech Incorporated will incorporate brand new avionics/electronics
and electrical systems (IS&S Air Data Display Units) that will perform
critical functions. These systems may be vulnerable to high-intensity
radiated fields 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 sytem 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 Boeing Model 707-300 airplanes modified
by AeroMech Incorporated. 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.
------------------------------------------------------------------------
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.
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
[[Page 68503]]
Working Group of the Aviation Rulemaking Advisory Committee.
Applicability
As discussed above, these special conditions are applicable to
Boeing Model 707-300 series airplanes modified by AeroMech
Incorporated. Should AeroMech Incorporated apply at a later date for a
supplemental type certificate to modify any other model included on
Type Certificate 4A26 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 Boeing Model 707-300 airplanes modified by AeroMech
Incorporated. 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 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 recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
0
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 Boeing Model 707-300
airplanes modified by AeroMech Incorporated.
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 December 1, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-30448 Filed 12-8-03; 8:45 am]
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