[Federal Register Volume 60, Number 149 (Thursday, August 3, 1995)]
[Rules and Regulations]
[Pages 39625-39627]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-19140]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 60, No. 149 / Thursday, August 3, 1995 /
Rules and Regulations
[[Page 39625]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM-115; Special Conditions No. 25-ANM-103]
Special Conditions: Modified Learjet Model 55, 55B and 55C
Airplanes; High Intensity Radiated Fields (HIRF)
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final special conditions; request for comments.
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SUMMARY: These special conditions are issued for the Learjet Models 55,
55B, and 55C airplanes modified by Duncan Aviation, Inc., of Lincoln,
Nebraska. These models will be equipped with a Flight Visions
Corporation, FV-2000 Head-Up Display System (HUD) that will perform
critical functions. The applicable regulations do not contain adequate
or appropriate safety standards for the protection of the HUD from the
effects of high-intensity radiated fields (HIRF). These special
conditions provide the additional safety standards that the
Administrator considers necessary to ensure that the critical functions
performed by this system are maintained when the airplane is exposed to
HIRF.
DATES: The effective date of these special conditions is July 26, 1995.
Comments must be received on or before September 18, 1995.
ADDRESSES: Comments on these final special conditions, request for
comments, may be mailed in duplicate to: Federal Aviation
Administration, Office of the Assistant Chief Counsel, Attn: Rules
Docket (ANM-7) Docket No. NM-115, 1601 Lind Avenue SW., Renton,
Washington, 98055-4056; or delivered in duplicate to the Office of the
Assistant Chief Counsel at the above address. Comments must be marked
``Docket No. NM-115.'' 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:
Mark Quam, FAA, Standardization Branch, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98055-4056; telephone (206) 227-2145.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA has determined that good cause exists for making these
special conditions effective upon issuance; however, interested persons
are invited to submit such written data, views, or arguments as they
may desire. Communications should identify the regulatory docket and
special conditions 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. These
special conditions may be changed in light of the comments received.
All comments submitted will be available in the Rules Docket for
examination by interested persons, both before and after the closing
date for comments. A report summarizing each substantive public contact
with FAA personnel concerning this rulemaking will be filed in the
docket. Persons wishing the FAA to acknowledge receipt of their
comments submitted in response to this request must submit with those
comments a self-addressed, stamped postcard on which the following
statement is made: ``Comments to Docket No. NM-115.'' The postcard will
be date stamped and returned to the commenter.
Background
On May 2, 1995, Duncan Aviation, Inc., of Lincoln, Nebraska,
applied for a supplemental type certificate to modify the Learjet
Models 55, 55B, and 55C airplanes. The Learjet Model 55 series airplane
is a business jet with two aft-mounted turbofan engines. The airplane
can carry two pilots and 8 passengers, depending on the exit and
interior configuration, and is capable of operating to an altitude of
51,000 feet. The proposed modification incorporates the installation of
a digital avionics system that will present critical functions on the
Head-up Display System (HUD), which is potentially vulnerable to high-
intensity radiated fields (HIRF) external to the airplane.
Supplemental Type Certification Basis
Under the provisions of Sec. 21.101 of the Federal Aviation
Regulations (FAR) Duncan Aviation, Inc., must show that the altered
Learjet Model 55 Series airplane continues 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 regulations incorporated by reference in Type Certificate No.
A10CE include the following for the Learjet Model 55, 55B and 55C
airplanes: 14 CFR part 25, dated February 1, 1965, as amended by 25-2
and 25-4.
In addition, for the Models 55 and 55B: Amendments 25-3, 25-7, 25-
10, 25-12, 25-18, 25-21 and 25-30, plus Sec. 25.955(b)(2) of Amendment
25-11; Sec. 25.954 of Amendment 25-14; Secs. 25.803(e), 25.811(f), 25-
853(a), 25.853(b), and 25-855(a) of Amendment 25-15; Sec. 25.1359 of
Amendment 25-17; Sec. 25.785(c) of Amendment 25-20; Secs. 25.251(c),
25.251(d), 25.251(e), 25.303, 25.305(b), 25.307(d), 25.331(a)(3),
25.335(b), 25.335(f), 25.337(b), 25.349(b), 25.351(a), 25.363,
25.395(a), 25.395(b), 25.471(a)(1), 25.471(a)(2), 25.473, 25.493(b),
25.499(b), 25.499(c), 25.499(d), 25.509(a)(3), 25.561(b)(3), 25.581,
25.607, 25.615, 25.619, 25.625, 25.629, 25.677, 25.697, 25.699, 25.701,
25.721, 25.723, 25.725, 25.727, 25.729, 25.733, 25.735, 25.865, 25.867,
25.871, 25.903(d), 25.934, 25.994, 25.1103(d), 25.1143(e), 25.1303,
25.1307, 25.1331, and 25.1585(c) of Amendment 25-23; Sec. 25.1013(e),
25.1305(c)(4), and 25.1305(c)(6) of Amendment 25-36; Secs. 25.815,
25.1322, and 25.1403 of Amendment 25-38; Secs. 25.903(e), 25.939, and
25.943 of Amendment 25-40, Sec. 25.255 of Amendment 25-42; Sec. 25.1326
of Amendment 25-43; Part 36 of the FAR effective December 1, 1969, as
amended through Amendment 36-10; Special Federal Aviation Regulation
(SFAR) 27 effective February 1, 1974, as amended through Amendment SFAR
27-2; and Special Conditions 25-99-CE-14.
[[Page 39626]]
For the Model 55 configured per ECR 2377A or modified per AAK 55-
83-4: In addition to the basis listed above, Special Conditions 25-ANM-
2 dated June 24, 1983.
For the Model 55C: Amendments 25-3, 25-7, 25-10, 25-12, 25-18, 25-
21, and 25-30; plus Sec. 25.955(b)(2) of Amend-Amendment 25-11;
Sec. 25.954 of Amendment 25-14; Sec. Sec. 25.803(e), 25.811(f), and
25.855(a) of Amendment 25-15; Sec. 25.1359 of Amendment 25-17;
Sec. 25.785(c) of Amendment 25-20; Sec. Sec. 25.251(c), 25.251(c),
25.251(e), 25.303, 25.305(b), 25.307(d), 25.331(a)(3), 25.335(b),
25.335(f), 25.337(b), 25.349(b), 25.351(a), 25.363, 25.395(a),
25.395(b), 25.471(a)(1), 25.471(a)(2), 25.473, 25.493(b), 25.499(b),
25.499(c), 25.499(d), 25.509(a)(3), 25.561(b)(3), 25.581, 25.607,
25.615, 25.619, 25.625, 25.629, 25.677, 25.697, 25.699, 25.701, 25.721,
25.723, 25.725, 25.727, 25.729, 25.733, 25.735, 25.865, 25.867, 25.871,
25.903(d), 25.934, 25.994, 25.1103(d), 25.1143(e), 25.1303(a)(1),
25.1303(a)(3), 25.1303(b), 25.1303(c), 25.1307, 25.1331, and 25.1585(c)
of Amendment 25-23; Sec. Sec. 25.1013(e), 25.1305(c)(4), and
25.1305(c)(6) of Amendment 25-36; Sec. Sec. 25.815, 25.1303(a)(2),
25.1322, and 25.1403 of Amendment 25-38; Sec. Sec. 25.903(e), 25.939,
and 25.943 of Amendment 25-40; Secs. 25.255 and 25.703 of Amendment 25-
42; Sec. 24.1326 of Amendment 25-43; Sec. 25.853 of Amendment 25-51;
Sec. 25.851 of Amendment 25-54; Part 36 of the FAR effective December
1, 1969, as amended through Amendment 36-15; SFAR 27 effective February
1, 1974, as amended through Amendment SFAR 27-6; Special Conditions 25-
ANM-2 dated June 24, 1983; and Special Conditions 25-99-CE-14 dated
March 10, 1981.
Compliance with structural provisions of Sec. 25.801(b) through (e)
and Sec. 25.807(d) has not been shown for Models 55, 55B, and 55C.
For Ice Protection: Sec. 25.1419. When ice protection system is
installed per ECR 1906, Model 55, 55B, and 55C.
For Noise Standards: Part 36 of the FAR. Compliance with Noise
Standards, Part 36, has been established for Models 55, 55B, and 55C
airplanes, when modified according to ECR 1511.
For Equivalent Level of Safety: Sec. 25.201(c)(2) (except Model
55C); Sec. 25.773(b)(2); Sec. 25.1305(r); Sec. 25.1505(b)(1) (except
Model 55C).
In addition, under Sec. 21.101(b)(1), the following sections of the
FAR apply to the HUD installation: Sec. 25.1309; Sec. 25.1321(a)(b)(d),
and (e); Sec. Sec. 25.1331, 25.1333, and 25.1335, as amended by
Amendment 25-41. These special conditions will form an additional part
of the supplemental 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 Learjet Model 55 Series airplane
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
Sec. Sec. 11.28 and 11.29, 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 applicant apply 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,
the special conditions would also apply to the other model under the
provisions of Sec. 21.101(a)(1).
Discussion
There is no specific regulation that address protection
requirements for electrical and electronic systems from high-intensity
radiated fields (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 modified Learjet Model 55 Series
airplanes that would require that the HUD be designed and installed to
preclude component damage and interruption of function due to the
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 the electronic command and control of the airplane, the
immunity of critical digital avionics systems, such as the Head-Up
Display, to HIRF must be established.
It is not possible to precisely define the HIRF to which the
airplanes 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 10KHz 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:
------------------------------------------------------------------------
Peak (V/ Average
Frequency M) (V/M)
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10 KHz--100 KHz....................................... 50 50
100 KHz--500 KHz...................................... 60 60
500 KHz--2000 KHz..................................... 70 70
2 MHz--30 MHz......................................... 200 200
30 MHz--100 MHz....................................... 30 30
100 MHz--200 MHz...................................... 150 33
200 MHz--400 MHz...................................... 70 70
400 MHz--700 MHz...................................... 4,020 935
700 MHz--1000 MHz..................................... 1,700 170
1 GHz-2GHz............................................ 5,000 990
2 GHz-4GHz............................................ 6,680 840
4 GHz-6GHz............................................ 6,850 310
6 GHz-8GHz............................................ 3,600 670
8 GHz-12GHz........................................... 3,500 1,270
12 GHz-18GHz.......................................... 3,500 360
18 GHz-40GHz.......................................... 2,100 750
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As discussed above, these special conditions are applicable to the
Learjet Model 55 Series airplane, modified by Duncan Aviation. Should
Duncan Aviation apply at a later date for a supplemental type
certificate to modify any other model included on Type Certificate No.
A10CE to incorporate 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 only certain unusual or novel design features
on Learjet Model 55, 55B, and 55C airplanes modified by Duncan
Aviation. It is not a rule of general applicability and affects only
the applicant who applied to the FAA for approval of this feature on
these airplanes.
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. It is
[[Page 39627]]
unlikely that prior public comment would result in a significant change
from the substance contained herein. For this reason, and 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 immediately. Therefore, these special
conditions are being made effective 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.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. app. 1344, 1348(c), 1352, 1354(a), 1355,
1421 through 1431, 1502, 1651(b)(2), 42 U.S.C. 1857f-10, 4321 et
seq.; E.O. 11514; and 49 U.S.C. 106(g).
The Special Conditions
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 Model 55,
55B, and 55C airplanes, as modified by Duncan Aviation:
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 airplanes is
exposed to high intensity radiated fields external to the airplane.
2. The following definition applies with respect to this special
condition: Critical Function. 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 26, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service, ANM-100.
[FR Doc. 95-19140 Filed 8-2-95; 8:45 am]
BILLING CODE 4910-13-M