[Federal Register Volume 69, Number 54 (Friday, March 19, 2004)]
[Rules and Regulations]
[Pages 12971-12973]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-6150]



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  Federal Register / Vol. 69, No. 54 / Friday, March 19, 2004 / Rules 
and Regulations  

[[Page 12971]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM274, Special Conditions No. 25-257-SC]


Special Conditions: Boeing Model 727-100 / -200 Series Airplanes; 
High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

-----------------------------------------------------------------------

SUMMARY: These special conditions are issued for Boeing Model 727-100 / 
-200 series airplanes modified by Aircraft Systems and Manufacturing. 
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 Collins Horizontal 
Situation Indicator (HSI) that performs critical functions. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for the protection of this system 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 March 5, 2004. 
Comments must be received on or before April 19, 2004.

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. NM274, 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. NM274.

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:

Comments Invited

    The FAA has determined that notice and opportunity for prior public 
comment is 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 October 23, 2003, Aircraft Systems & Manufacturing, Georgetown, 
Texas, applied to the FAA, Fort Worth Special Certification Office, for 
a supplemental type certificate (STC) to modify Boeing Model 727-100- / 
-200 series airplanes. These models are currently approved under Type 
Certificate No. A3WE. The Model 727-100 / -200 series airplanes are low 
wing, pressurized transport category airplanes with three fuselage-
mounted engines. The modification incorporates the installation of a 
Collins Horizontal Situation Indicator (HSI). The information presented 
is flight critical. The avionics/electronics and electrical systems 
installed in these airplanes 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, Aircraft Systems & 
Manufacturing must show that the Model 727-100 / -200 series airplanes 
as changed, continue to meet the applicable provisions of the 
regulations incorporated by reference in Type Certificate No. A3WE, 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. 
A3WE include Civil Air Regulations (CAR) 4b, as amended by amendment 
4b-1 through 4b-11 and additional requirements identified in the type 
certificate data sheet that are not relevant to these special 
conditions.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., CAR 4b, as amended) do not contain adequate or 
appropriate safety standards for the modified Boeing Model 727-100 / -
200 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 Boeing Model 727-100 / -200 series airplanes must 
comply with the fuel vent and exhaust emission

[[Page 12972]]

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 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 Aircraft Systems & Manufacturing apply at a 
later date for a supplemental type certificate to modify any other 
model included on Type Certificate No. A3WE 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.

Novel or Unusual Design Features

    As noted earlier, the modified Boeing Model 727- 100 / -200 series 
airplanes will incorporate a new avionics/electronics and electrical 
system that will perform critical functions. This system 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 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 Boeing Model 727-100 / -200 series 
airplanes modified by Aircraft Systems & Manufacturing. 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, 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-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 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
------------------------------------------------------------------------
 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 727-100 / -200 series airplanes modified by Aircraft 
Systems & Manufacturing. Should Aircraft Systems & Manufacturing apply 
at a later date for a supplemental type certificate to modify any other 
model on Type Certificate A3WE to incorporate the same or similar novel 
or unusual design feature, these special conditions would apply to that 
model as well as under the provisions of Sec.  21.101.

Conclusion

    This action affects only certain novel or unusual design features 
on Boeing Model 727-100 / -200 series airplanes modified by Aircraft 
Systems &

[[Page 12973]]

Manufacturing. 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 the Boeing Model 727-100 
/ -200 series airplanes modified by Aircraft Systems & Manufacturing.
    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 March 5, 2004.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-6150 Filed 3-18-04; 8:45 am]
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