[Federal Register Volume 63, Number 57 (Wednesday, March 25, 1998)]
[Proposed Rules]
[Pages 14381-14383]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-7826]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM147; Notice No. 25-98-02-SC]
Special Conditions: Boeing Model 757-300; High-Intensity Radiated
Fields
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This notice proposes special conditions for the Boeing Model
757-300. This airplane will utilize new avionics/electronic systems
that provide critical data to the flightcrew. The applicable
regulations do not contain adequate or appropriate safety standards for
the protection of these systems from the effects of high-intensity
radiated fields. These proposed special conditions contain the
additional safety standards that the Administrator considers necessary
to establish a level of safety equivalent to that established by the
existing airworthiness standards.
DATES: Comments must be received on or before April 24, 1998.
ADDRESSES: Comments on this proposal may be mailed in duplicate to:
Federal Aviation Administration, Office of the Regional Counsel, Attn:
Rules Docket (ANM-7), Docket No. NM147, 1601 Lind Avenue SW., Renton,
Washington, 98055-4056; or delivered in duplicate to the Office of the
Regional Counsel at the above address. Comments must be marked: Docket
No. NM147. 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: John Dimtroff, 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) 227-2117 or facsimile (425)
227-1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
Interested persons are invited to participate in the making of
these proposed special conditions by submitting such written data,
views, or arguments as they may desire. Communications should identify
the regulatory docket or notice 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
before further rulemaking action on this proposal is taken. The
proposals contained in this notice may be changed in light of the
comments received. All comments received will be available, both before
and after the closing date for comments, in the Rules Docket for
examination by interested parties. 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 this
notice must include a self-addressed, stamped postcard on which the
following statement is made: ``Comments to Docket No. NM147.'' The
[[Page 14382]]
postcard will be date stamped and returned to the commenter.
Background
On February 21, 1996, the Boeing Commercial Airplane Group, P. O.
Box 3707, Seattle, Washington 98124-2207, applied for an amendment to
Type Certificate No. A2NM to include the new Model 757-300, a
derivative of the 757-200. The 757-300 is a swept-wing, conventional-
tail, twin-engine, turbofan-powered transport. Each engine will be
capable of delivering 43,100 pounds of thrust. The flight controls are
unchanged beyond those changes deemed necessary to accommodate the
stretched configuration. The airplane has a seating capacity of up to
289, and a maximum takeoff weight of 270,000 pounds (122,470 Kg).
Type Certification Basis
Under the provisions of Title 14 CFR 21.101, Boeing must show that
the Model 757-300 meets the applicable provisions of the regulations
incorporated by reference in Type Certificate No. A2NM, or the
applicable regulations in effect on the date of application for the
change to the Model 757-300. The regulations incorporated by reference
in the type certificate are commonly referred to as the ``original type
certification basis.'' The regulations incorporated by reference in
Type Certificate No. A2NM include 14 CFR part 25, as amended by
Amendments 25-1 through 25-45, and certain other later amended sections
of part 25 that are not relevant to these proposed special conditions.
Except for certain earlier amended sections of part 25 that are not
relevant to these proposed special conditions, Boeing has chosen to
comply with part 25 as amended by Amendments 25-1 through 25-85, the
applicable regulations in effect on the date of application. In
addition to the applicable airworthiness regulations and special
conditions, the 757-300 must comply with the fuel vent and exhaust
emission requirements of part 34, effective September 10, 1990, plus
any amendments in effect at the time of certification; and the noise
certification requirements of part 36, effective December 1, 1969, as
amended by Amendment 36-1 through the amendment in effect at the time
of certification. The special conditions that may be developed as a
result of this notice will form an additional part of the type
certification basis.
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 757-300 because of a novel or
unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16 to establish a level of safety equivalent to
that established in the regulations.
Special conditions, as appropriate, are issued in accordance with
Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28
and 11.29(b), 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 the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design feature, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, the special conditions would also apply to the
other model under the provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
The 757-300 airplane avionics enhancement will utilize electronic
systems that perform critical functions, including the following
airframe Line Replaceable Units (LRU): Multi-Mode Receiver (MMR),
Flight Control Computer (FCC), Yaw Damper Stabilizer Trim Module (YSM),
Air Data Inertial Reference System (ADIRS), and the Allied Signal Radio
Altimeter (RA). These systems may be vulnerable to high-intensity
radiated fields (HIRF) external to the airplane.
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 electrical and electronic 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 757-300, which require that new
technology electrical and electronic systems, such as the MMR, FCC,
YSM, ADIRS, and RA, 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
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 paragraphs 1 or 2 below:
1. A minimum threat of 100 volts per meter peak 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 following field
strengths for the frequency ranges indicated.
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Field Strength (volts per meter)
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Frequency US UK/European Consolidated
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Peak Avg. Peak Avg. Peak Avg.
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10 kHz-100 kHz............................................ 30 30 50 50 50 50
100 kHz-500 kHz........................................... 40 30 60 60 60 60
500 kHz-2 MHz............................................. 30 30 70 70 70 70
2 MHz-30 MHz.............................................. 190 190 200 200 200 200
30 MHz-70 MHz............................................. 20 20 30 30 30 30
70 MHz-100 MHz............................................ 20 20 30 30 30 30
[[Page 14383]]
100 MHz-200 MHz........................................... 30 30 150 30 150 30
200 MHz-400 MHz........................................... 30 30 70 70 70 70
400 MHz-700 MHz........................................... 80 80 700 40 700 80
700 MHz-1 GHz............................................. 690 240 1700 80 1700 240
1 GHz-2 GHz............................................... 970 70 5000 360 5000 360
2 GHz-4 GHz............................................... 1570 350 4500 360 4500 360
4 GHz-6 GHz............................................... 7200 300 5200 300 7200 300
6 GHz-8 GHz............................................... 130 80 2000 330 2000 330
8 GHz-12 GHz.............................................. 2100 80 3500 270 3500 270
12 GHz-18 GHz............................................. 500 330 3500 180 3500 330
18 GHz-40 GHz............................................. 780 20 (\1\) (\1\) 780 20
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\1\ NA.
The field strengths are expressed in terms of peak root-mean-square (rms) values.
The threat levels identified above differ from those used in
previous special conditions and 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. In general, these standards are
less critical than the threat level that was previously used as the
basis for earlier special conditions.
Applicability
As discussed above, these special conditions would be applicable
initially to the 757-300 airplane. Should Boeing apply at a later date
for a change to the type certificate to include another model
incorporating the same novel or unusual design feature, the special
conditions would apply to that model as well, under the provisions of
Sec. 21.101(a)(1).
Conclusion
This action affects certain design features only on the Model 757-
300. It is not a rule of general applicability and affects only the
manufacturer who applied to the FAA for approval of these features on
this model.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and record keeping
requirements.
The authority citation for these proposed special conditions is as
follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the Boeing 757-300 series airplanes.
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 this special condition, 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 March 17, 1998.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-7826 Filed 3-24-98; 8:45 am]
BILLING CODE 4910-13-P
