[Federal Register: March 3, 2003 (Volume 68, Number 41)]
[Rules and Regulations]
[Page 9854-9856]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr03mr03-2]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM240, Special Conditions No. 25-227-SC]
Special Conditions: Learjet Model 24, 24A, 24B, 24B-A, 24C, 24D,
24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F 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 Learjet Model 24, 24A,
24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D
and 25F airplanes modified by Royal Air, Inc. These airplanes, as
modified, 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 the Innovative Solutions & Support (IS&S) Air Data
Display Units (ADDU) and Air Data Sensor. 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 February 21,
2003. Comments must be received on or before April 2, 2003.
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. NM240, 1601 Lind
Avenue SW., Renton, Washington 98055-4056; or delivered in duplicate to
the Transport Airplane Directorate at the above address. Comments must
be marked: Docket No. NM240. Comments may be inspected in the Rules
Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
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-
1149.
SUPPLEMENTARY INFORMATION:
FAA's Determination as to Need for Public Process
The FAA has determined that notice and opportunity for prior public
comment are unnecessary in accordance with 14 CFR 11.38, because the
FAA has provided previous opportunities to comment on substantially
identical special conditions and has fully considered and addressed all
the substantive comments received. Based on a review of the comment
history and the comment resolution, the FAA is satisfied that new
comments are unlikely. 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 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 in light of 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 August 17, 2002, Royal Air, Inc., 2141 Airport Road, Waterford,
Michigan 48327, applied for a supplemental type certificate (STC) to
modify Learjet Model 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F,
24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes approved under Type
Certificate No. A10CE. The Learjet Model 24/25 series airplanes are
small transport category airplanes powered by two turbojet engines,
with maximum takeoff weights of up to 15,000 pounds. These airplanes
operate with a 2-pilot crew and can seat 6 to 8 passengers. The
modification incorporates the installation of the Innovative Solutions
& Support (IS&S) Air Data Display Units (ADDU) and Air Data Sensor. The
ADDU digital air data computing altimeter provides flight critical
functions. These advanced 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, Amendment 21-69, effective
September 16, 1991, Royal Air must show that the Learjet Model 24, 24A,
24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D
and 25F 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. Subsequent changes have been made
to Sec. 21.101 as part of Amendment 21-77, but those changes do not
become effective until June 10, 2003. The regulations incorporated by
reference in the type certificate are commonly referred to as the
``original type certification basis.'' The original type certification
basis for the modified Learjet Model 24, 24A, 24B, 24B-A, 24C, 24D,
24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes
includes 14 CFR part 25, dated February 1, 1965, through Amendments 25-
2 and 25-4; and 14 CFR part 25, dated February 1, 1965, through
Amendment 25-18, except for special conditions and exceptions noted in
Type Certificate Data Sheet (TCDS) A10CE.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate
or appropriate safety standards for the Learjet Model 24, 24A, 24B,
24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and
[[Page 9855]]
25F airplanes because of novel or unusual design features, special
conditions are prescribed under the provisions of Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Learjet Model 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A,
24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes must comply
with the fuel vent and exhaust emission requirements of 14 CFR part 34
and the noise certification requirement of part 36, including Amendment
36-1.
Special conditions, as defined in Sec. 11.19, are issued in
accordance with Sec. 11.38, 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 Royal Air apply at a later date for design
change approval to modify any other model already included on the same
type certificate 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(a)(1).
Novel or Unusual Design Features
As noted earlier, the Learjet Model 24, 24A, 24B, 24B-A, 24C, 24D,
24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes will
incorporate new Air Data Display Units (ADDU) and Air Data Sensor that
will perform critical functions. These systems have the potential to be
vulnerable to high-intensity radiated fields (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 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 Learjet Model 24, 24A, 24B, 24B-A, 24C,
24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F airplanes
modified by Royal Air, Inc. 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, plus the advent of space and satellite communications,
coupled with electronic command and control of the airplane, the
immunity of critical digital 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 following table 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-500kHz.................................... 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
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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 Model 24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A,
25, 25A, 25B, 25C, 25D and 25F airplanes modified by Royal Air, Inc.
Should Royal Air 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 or similar novel or unusual design
feature, these special conditions would apply to that model as well
under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain design features on Learjet Model
24, 24A, 24B, 24B-A, 24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B,
25C, 25D and 25F airplanes modified by Royal Air. 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 the special conditions for these airplanes 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:
[[Page 9856]]
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 Learjet Model 24, 24A, 24B, 24B-A,
24C, 24D, 24D-A, 24E, 24F, 24F-A, 25, 25A, 25B, 25C, 25D and 25F
airplanes modified by Royal Air, Inc.
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 external to the airplane.
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 February 21, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 03-4796 Filed 2-28-03; 8:45 am]
BILLING CODE 4910-13-P