[Federal Register Volume 68, Number 174 (Tuesday, September 9, 2003)]
[Rules and Regulations]
[Pages 53026-53028]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-22798]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM263, Special Conditions No. 25-245-SC]


Special Conditions: Sabreliner Model NA-265 Series 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 Sabreliner Model NA-
265 series airplanes, modified by Sabreliner Corporation. 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 Air Data systems that perform critical 
functions by providing altitude, airspeed, or other critical data. 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 provided by the existing airworthiness standards.

DATES: The effective date of these special conditions is August 28, 
2003. Comments must be received on or before October 9, 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. NM263, 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. NM263.

FOR FURTHER INFORMATION CONTACT: Mark Quam, FAA, Standardization 
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-2145; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment are 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 May 21, 2003, Sabreliner Corporation, Pierre Laclede Center, 
7733 Forsyth Boulevard, Suite 1500, St. Louis, Missouri 63105-1821, 
applied for a supplemental type certificate (STC) to modify Sabreliner 
Model NA-265 series airplanes. These airplanes are approved under Type 
Certificate No. A2WE. The Model NA-265 series are small transport 
category airplanes powered by two aft-mounted Pratt and Whitney Turbo 
Wasp JT12A engines, with the exception of the Model NA-265-65, which 
has two Air Research TFE731 turbofan engines, and the Model NA-265-80, 
which has two GE Model CF700 turbofan engines. These airplanes operate 
with a 2-pilot crew and can hold from 4 to 10 passengers depending on 
the model within the series. The NA-265 series have a maximum takeoff 
weight of 17,450 to 24,000 pounds, depending on the brake installation 
and model within the series.
    The modification incorporates the installation of Air Data systems 
(combinations of Air Data Display Units, Air Computer, Air Data Sensor, 
and/or Altimeter) that perform critical functions by providing 
altitude, airspeed, or other critical data. These systems use 
electronics to a far greater extent than the original instrument 
systems, and may be more susceptible to electrical and magnetic 
interference caused by high-intensity radiated fields (HIRF). The 
disruption of these signals could result in loss of altitude, or 
present misleading information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Sabreliner Corporation must

[[Page 53027]]

show that the Model NA-265 series airplanes, as changed, continue to 
meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. A2WE, 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 Sabreliner NA-265 series airplanes includes 
Civil Air Regulation (CAR) 4b, dated December 31, 1953, as amended by 
Amendments 4b-1 through 4b-9. In addition, under Sec.  21.101(b)(1), 
Amendment 25-69, the following sections of 14 CFR part 25 apply to the 
air data, altimeter, and display systems installed on the Sabreliner 
NA-265 series airplanes: Sec. Sec.  25.1309(a), (c), (e), (f), and (g), 
25.1321(a), (b), (d), and (e), 25.1331, and 25.1335 as amended by 
Amendment 25-41; and Sec.  25.1316, as amended by Amendment 25-80. The 
certification basis also includes other amendments and special 
conditions, as noted in Type Certificate Data Sheet (TCDS) No. A2WE, 
that are not relevant to these special conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (that is, CAR 4b, as amended) do not contain adequate or 
appropriate safety standards for the Sabreliner Model NA-265 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 Sabreliner Model NA-265 series airplanes must comply 
with the fuel vent and exhaust emission requirement of SFAR 27 (now 
codified as 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 Sabreliner Corporation apply at a later date 
for a supplemental type certificate to modify any other model included 
on Type Certificate No. A2WE to incorporate the same or similar novel 
or unusual design features, 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 Sabreliner Model NA-265 series airplanes 
modified by Sabreliner Corporation will incorporate the installation of 
Air Data systems that perform critical functions. Because these 
advanced systems use electronics to a far greater extent than the 
original altimetry system, they may be more susceptible to electrical 
and magnetic interference caused by high-intensity radiated fields 
(HIRF) 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, these systems are 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 Model NA-265 series airplanes, modified 
by Sabreliner to include the new Air Data systems. These special 
conditions require that the Air Data systems, which 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 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 
identified 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
100kHz-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-1GHz..................................          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
------------------------------------------------------------------------
Note.--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 
Sabreliner Model NA-265 series airplanes modified by Sabreliner. Should 
Sabreliner Corporation apply at a later date for a supplemental type 
certificate to modify any other model included on Type Certificate No. 
A2WE 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.

Conclusion

    This action affects only certain novel or unusual design features 
on Sabreliner

[[Page 53028]]

Model NA-265 series airplanes modified by Sabreliner Corporation. 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.

    The authority citation for these special conditions is as follows:

    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 supplemental type certification basis for Sabreliner Model NA-265 
series airplanes modified by Sabreliner Corporation.
    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 August 28, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-22798 Filed 9-8-03; 8:45 am]
BILLING CODE 4910-13-P