[Federal Register: March 19, 2004 (Volume 69, Number 54)]
[Rules and Regulations]
[Page 12971-12973]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19mr04-1]
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Rules and Regulations
Federal Register
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[[Page 12971]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM274, Special Conditions No. 25-257-SC]
Special Conditions: Boeing Model 727-100 / -200 Series Airplanes;
High Intensity Radiated Fields (HIRF)
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions; request for comments.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for Boeing Model 727-100 /
-200 series airplanes modified by Aircraft Systems and Manufacturing.
These modified airplanes will have a novel or unusual design feature
when compared to the state of technology envisioned in the
airworthiness standards for transport category airplanes. The
modification incorporates the installation of a Collins Horizontal
Situation Indicator (HSI) that performs critical functions. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for the protection of this system 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 established by the existing airworthiness standards.
DATES: The effective date of these special conditions is March 5, 2004.
Comments must be received on or before April 19, 2004.
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. NM274, 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. NM274.
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 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 October 23, 2003, Aircraft Systems & Manufacturing, Georgetown,
Texas, applied to the FAA, Fort Worth Special Certification Office, for
a supplemental type certificate (STC) to modify Boeing Model 727-100- /
-200 series airplanes. These models are currently approved under Type
Certificate No. A3WE. The Model 727-100 / -200 series airplanes are low
wing, pressurized transport category airplanes with three fuselage-
mounted engines. The modification incorporates the installation of a
Collins Horizontal Situation Indicator (HSI). The information presented
is flight critical. The avionics/electronics and electrical systems
installed in these airplanes 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, Aircraft Systems &
Manufacturing must show that the Model 727-100 / -200 series airplanes
as changed, continue to meet the applicable provisions of the
regulations incorporated by reference in Type Certificate No. A3WE, 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 regulations incorporated by reference in Type Certificate No.
A3WE include Civil Air Regulations (CAR) 4b, as amended by amendment
4b-1 through 4b-11 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 (i.e., CAR 4b, as amended) do not contain adequate or
appropriate safety standards for the modified Boeing Model 727-100 / -
200 series 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 727-100 / -200 series airplanes must
comply with the fuel vent and exhaust emission
[[Page 12972]]
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 Aircraft Systems & Manufacturing apply at a
later date for a supplemental type certificate to modify any other
model included on Type Certificate No. A3WE 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, the modified Boeing Model 727- 100 / -200 series
airplanes will incorporate a new avionics/electronics and electrical
system that will perform critical functions. This system 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 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 Boeing Model 727-100 / -200 series
airplanes modified by Aircraft Systems & Manufacturing. 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
indicated 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
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 Working Group of the
Aviation Rulemaking Advisory Committee.
Applicability
As discussed above, these special conditions are applicable to
Boeing Model 727-100 / -200 series airplanes modified by Aircraft
Systems & Manufacturing. Should Aircraft Systems & Manufacturing apply
at a later date for a supplemental type certificate to modify any other
model on Type Certificate A3WE 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 Boeing Model 727-100 / -200 series airplanes modified by Aircraft
Systems &
[[Page 12973]]
Manufacturing. 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 727-100
/ -200 series airplanes modified by Aircraft Systems & Manufacturing.
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 March 5, 2004.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-6150 Filed 3-18-04; 8:45 am]
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