[Federal Register Volume 68, Number 88 (Wednesday, May 7, 2003)]
[Rules and Regulations]
[Pages 24336-24338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-11228]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM251, Special Conditions No. 25-234-SC]


Special Conditions: Raytheon HS.125 Series 700A/B 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 Raytheon HS.125A 
Series 700A/B airplanes, modified by Midcoast Aviation, Inc. 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 dual Rockwell Collins Air Data 
Computers (ADC-87A) and ALI-80A altimeters. 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 April 22, 
2003. Comments must be received on or before June 6, 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. NM251, 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. NM251.

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:

FAA Determination as to Need for Public Process

    The FAA has determined that notice and opportunity for prior public

[[Page 24337]]

comment is impracticable because these procedures would significantly 
delay certification of the airplane and thus delivery of the affected 
airplane. 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 document 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 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 February 28, 2003, Midcoast Aviation, Inc., 14 Archview 
Drive, Cahokia, Illinois 62206, applied for a supplemental type 
certificate (STC) to modify the Raytheon HS.125 Series 700A and Series 
700B airplanes approved under Type Certificate No. A3EU. The HS.125 
Series 700A and Series 700B are low wing corporate jets with two 
Garrett AiResearch TFE-731 engines mounted on the aft fuselage. The 
airplane carries two crewmembers and up to 15 passengers. The maximum 
ramp weight varies between 24,800 Lbs. and 25,500 Lbs. depending on the 
fuel tanks installed. The airplane is approved to operate up to 41,000 
feet altitude. The modification incorporates the installation of dual 
Rockwell Collins Air Data Computers (ADC-87A) and ALI-80A altimeters.
    The dual Rockwell Collins ADCs and altimeters replace the existing 
altimetry system. This system uses electronics to a far greater extent 
than the original altimetry system, 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, Amendment 21-69, effective 
September 16, 1991, Midcoast Aviation, Inc. must show that the Raytheon 
HS.125A Series 700A/B airplanes, as changed, continue to meet the 
applicable provisions of the regulations incorporated by reference in 
Type Certificate No. A3EU, 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 certification basis for the 
modified Raytheon HS.125A Series 700A/B airplanes includes 14 CFR part 
25 effective February 1, 1965, as amended by Amendments 25-1 through 
25-20. Other applicable amendments, regulations, and special conditions 
are noted in Type Certificate Data Sheet A3EU.
    If the Administrator finds that the applicable airworthiness 
regulations (part 25, as amended) do not contain adequate or 
appropriate safety standards for the Raytheon HS.125 Series 700A/B 
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 Raytheon HS.125 Series 700A/B airplanes must comply 
with the fuel vent and exhaust emission requirements of 14 CFR part 34 
and the noise certification requirements 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(b)(2), Amendment 21-69, effective 
September 16, 1991.
    Special conditions are initially applicable to the model for which 
they are issued. Should Midcoast Aviation, Inc. apply at a later date 
for a supplemental type certificate 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), Amendment 21-69, effective September 16, 1991.

Novel or Unusual Design Features

    The Raytheon HS.125A Series 700A/B airplanes modified by Midcoast 
Aviation, Inc. will incorporate the installation of dual Rockwell 
Collins Air Data Computers (ADC-87A) and ALI-80A altimeters. 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 Raytheon HS.125A Series 700A/B airplanes, 
modified by Midcoast Aviation, Inc. These special conditions require 
that the new dual Rockwell Collins Air Data Computers (ADC-87A) with 
ALI-80A altimeters, 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 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-

[[Page 24338]]

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 MHz-2 kHz...................................          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 
Raytheon HS.125 Series 700A/B airplanes modified by Midcoast Aviation, 
Inc. to include the dual Rockwell Collins Air Data Computers (ADC-87A) 
and ALI-80A altimeters. Should Midcoast Aviation, Inc. apply at a later 
date for a supplemental type certificate to modify any other model 
already included on Type Certificate A3EU 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), 
Amendment 21-69, effective September 16, 1991.

Conclusion

    This action affects only certain novel or unusual design features 
on Raytheon HS.125 Series 700A/B airplanes modified by Midcoast 
Aviation, Inc. 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 Raytheon HS.125 Series 
700A/B airplanes modified by Midcoast Aviation, 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.
    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 April 22, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-11228 Filed 5-6-03; 8:45 am]
BILLING CODE 4910-13-P