[Federal Register: July 15, 2004 (Volume 69, Number 135)]
[Rules and Regulations]
[Page 42329-42331]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15jy04-1]
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Rules and Regulations
Federal Register
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[[Page 42329]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM286; Special Conditions No. 25-270-SC]
Special Conditions: Learjet Inc., Model 55, 55B and 55C
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 Learjet Inc., Model
55, 55B and 55C airplanes modified by Garrett Aviation Services. 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 two Honeywell N1 Digital Electronic
Engine Controls (DEEC) that 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 established by the
existing airworthiness standards.
DATES: The effective date of these special conditions is July 1, 2004.
Comments must be received on or before August 16, 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. NM286, 1601 Lind
Avenue, SW., Renton Washington, 98055-4056; or delivered in duplicate
to the Transport Directorate at the above address. All comments must be
marked: Docket No. NM286.
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 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 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 thru 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 this
proposal, 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 December 1, 2003, Garrett Aviation Services, 1200 North Airport
Drive, Capital Airport Springfield, IL 62707, applied for a
Supplemental Type Certificate (STC) to modify Learjet Inc., Model 55,
55B and 55C airplanes approved under Type Certificate No. A10CE. The
Learjet Inc., Model 55, 55B and 55C airplanes are transport category
airplanes. The Learjet Inc., Model 55, 55B and 55C airplanes are
powered by two Garrett TFE731-3A-2B turbofans with a maximum takeoff
weight of 21,500 pounds. These aircraft operate with a 2-pilot crew and
can hold up to 10 passengers. The modification incorporates the
installation of Honeywell N1 Digital Electronic Engine Controls (DEEC).
The N1 DEEC is a replacement for the existing Analog Electronic Engine
Control (EEC), while also providing additional functional capability in
the system. The digital avionics/electronics and electrical systems
installed under this project in these airplanes have the potential to
be vulnerable to HIRF external to the airplane.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Garrett Aviation Services
must show that the Learjet Inc., Model 55, 55B and 55C airplanes, as
changed, continue to meet the applicable provisions of the regulations
incorporated by reference in Type Certificate No. A10CE, 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 Learjet Inc., Model 55,
55B and 55C airplanes include 14 CFR part 25, dated February 1, 1964,
as amended by Amendments 25-1 through 25-20 except for special
conditions and exceptions noted in Type Certificate Data Sheet (TDCS)
A10CE.
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 Learjet Inc., Model 55, 55B and
55C airplanes because of novel or unusual design features, special
[[Page 42330]]
conditions are prescribed under the provisions Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Learjet Inc., Model 55, 55B and 55C airplanes must
comply with the noise certification requirement of 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 Garrett Aviation Services apply at a later date
for a supplemental type certificate to modify any other model included
on the same type certificate to incorporate the same 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 Learjet Inc., Model 55, 55B and 55C airplanes modified by
Garrett Aviation Services will incorporate Honeywell N1 DEEC that will
perform critical functions. These systems have to potential to be
vulnerable to HIRF external to the airplane. The current airworthiness
standards (14 CFR part 25) do not contain adequate or appropriate
safety standards for the protection of this equipment from the adverse
effect 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 that is equivalent to
that intended by the regulations incorporated by reference; special
conditions are needed for Learjet Inc., Models 55, 55B and 55C
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 following table 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-30MHz....................................... 100 100
30 MHz-70 MHz..................................... 50 50
70 MHz-100MHz..................................... 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-4GHz........................................ 3000 200
4 GHz-6 GHz....................................... 3000 200
6 GHz-8 GHz....................................... 1000 200
8GHz-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
Learjet Inc., Model 55, 55B and 55C airplanes modified by Garret
Aviation Services. Should Garrett Aviation Services apply at a later
date for a supplemental type certificate to modify any other model
included on the same type certificate to incorporate the same novel or
unusual design feature, these special conditions would apply to that
model as well under the provisions of Sec. 21.101.
Conclusion
This action affects only certain novel or unusual design features
on the Learjet Inc., Model 55, 55B and 55C airplanes modified by
Garrett Aviation Services. 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 record keeping
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 Learjet Inc., Model
55, 55B and 55C 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
[[Page 42331]]
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 July 1, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 04-16101 Filed 7-14-04; 8:45 am]
BILLING CODE 4910-13-P