[Federal Register Volume 67, Number 194 (Monday, October 7, 2002)]
[Rules and Regulations]
[Pages 62339-62341]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-25470]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM230; Special Conditions No. 25-215-SC]


Special Conditions: Boeing Model 737 -100, -200, and -300 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 Boeing 737 -100, -200, 
& -300 series airplanes modified by Aircraft Systems & Manufacturing, 
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 a new IS&S Digital Air 
Data Control System that performs 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 September 26, 
2002. Comments must be received on or before November 6, 2002.

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. NM230, 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. NM230. 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: Connie Beane, FAA, Standardization 
Branch, ANM-113, Transport Airplane

[[Page 62340]]

Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
Renton, Washington 98055-4056; telephone (425) 227-2796; facsimile 
(425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment hereon are impracticable because these procedures would 
significantly delay certification, and thus delivery, of the affected 
airplane. 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 4:00 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 June 17, 2002, Aircraft Systems & Manufacturing, Inc., 
Georgetown, TX, applied for a supplemental type certificate (STC) to 
modify Boeing 737-100/-200/-300 series airplanes. These airplanes are 
low-wing, pressurized transport category airplanes with two wing-
mounted jet engines. They are capable of seating between 100 and 150 
passengers, depending upon the model and configuration. The 
modification incorporates the installation of a dual Air Data Control 
System consisting of a single air data computer and electronic 
altimeter for display of No. 1 altitude data, an air data display unit 
(ADDU) for display of No. 2 altitude data and an altitude alerter. 
These systems have a 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, Aircraft Systems & Manufacturing, Inc. must show 
that the Boeing 737-100, -200, and -300 series airplanes, as modified 
to include the new IS&S Digital Air Data Control System, continue to 
meet the applicable provisions of the regulations incorporated by 
reference in Type Certificate No. A16WE or the applicable regulations 
in effect on the date of application for the change. Subsequent changes 
have been made to 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 specific 
regulations included in the certification basis for the Boeing 737-100, 
-200, and -300 series airplanes include 14 CFR part 25, as amended by 
amendments 25-1 through 25-3, 25-7, 25-8, and 25-15.
    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 Boeing 737 -100, -200, and -300 
Series airplanes because of a novel or unusual design feature, special 
conditions are prescribed under the provisions of 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Boeing 737 -100, -200, and -300 series airplanes must 
comply with the fuel vent and exhaust emission requirements of 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 11.38, and become part of the airplane's type 
certification basis in accordance with 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 Aircraft Systems & Manufacturing, Inc. 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(a)(1), 
Amendment 21-69, effective September 16, 1991.

Novel or Unusual Design Features

    As noted earlier, the Boeing 737-100, -200, and -300 series 
airplanes modified by Aircraft Systems & Manufacturing, Inc. will 
incorporate a new IS&S Digital Air Data Control System that will 
perform critical functions. These systems may be vulnerable to high-
intensity radiated fields external to the airplane. The current 
airworthiness standards of part 25 do not contain adequate or 
appropriate safety standards that address the protection of this 
equipment from the adverse effects of HIRF. Accordingly, these systems 
are considered to be novel or unusual design features.

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 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 the Boeing 737-100, -200, and -300 series 
airplanes modified by Aircraft Systems & Manufacturing, Inc. These 
special conditions will require that the new IS&S Digital Air Data 
Control System, which performs 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

[[Page 62341]]

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 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-500kHz..................................          50          50
500 kHz-2MHz....................................          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-8GHz......................................        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 
Boeing Model 737-100, -200, and -300 series airplanes modified by 
Aircraft Systems & Manufacturing, Inc. to install new IS&S Digital Air 
Data Control System. Should Aircraft Systems & Manufacturing, Inc. 
apply at a later date for a supplemental type certificate to modify any 
other model included on Type Certificate A16WE to incorporate the same 
novel or unusual design feature, these special conditions would apply 
to that model as well under the provisions of 21.101(a)(1), Amendment 
21-69, effective September 16, 1991.

Conclusion

    This action affects only certain design features on the Boeing 
Model 737-100, -200, and -300 series airplanes modified by Aircraft 
Systems & Manufacturing, Inc. to include the new IS&S Digital Air Data 
Control System. 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 airplanes.
    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 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 the Boeing 737-100, -200, 
and -300 series airplanes modified by Aircraft Systems & Manufacturing, 
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 capabilities 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 September 26, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-25470 Filed 10-4-02; 8:45 am]
BILLING CODE 4910-13-P