[Federal Register Volume 62, Number 145 (Tuesday, July 29, 1997)]
[Rules and Regulations]
[Pages 40427-40429]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-19858]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM-143; Special Conditions No. 25-ANM-130]


Special Conditions: International Aviation Services, Ltd.; Boeing 
Model 747-SP Airplane; 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 Model 747-SP 
airplanes modified by International Aviation Services, Ltd. These 
airplanes will have novel and unusual design features when compared to 
the state of technology envisioned in the airworthiness standards for 
transport category airplanes. 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 July 17, 1997. 
Comments must be received on or before August 28, 1997.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Office of the Assistant 
Chief Counsel, Attn: Rules Docket (ANM-7), Docket No. NM-143, 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-143. 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: Tom Groves, FAA, Standardization 
Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-1503; facsimile (425) 227-1149.

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 condition 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-143.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On August 8, 1996, International Aviation Services, Ltd. applied 
for a supplemental type certificate (STC) to modify Boeing Model 747-SP 
airplanes

[[Page 40428]]

listed on Type Certificate A20WE. The modification includes the 
installation of a 5-tube electronic flight instrument system (EFIS) 
that will replace the existing electro-mechanical horizontal situation 
indicator (HSI) and attitude director indicator (ADI). These systems, 
which display flight critical information, are vulnerable to high-
intensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

    Under the provisions of 14 CFR Sec. 21.101, International Aviation 
Services, Ltd. must show that the Boeing Model 747-SP, as changed, 
continues to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate A20WE, 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 Model 747-SP includes 14 CFR part 
25, as amended by Amendments 25-1 through 25-8 and certain later 
amendments, special conditions, exemptions, and optional requirements 
listed in the type certificate data sheet that are not relevant to 
these special conditions. In addition, the certification basis for the 
modifications, and for areas affected by the modifications, will be 
amended to include the following sections:

------------------------------------------------------------------------
            Section             Amendment              Title            
------------------------------------------------------------------------
25.779(a).....................     25-72   Motion and effect of cockpit 
                                            controls.                   
25.1303.......................     25-38   Flight and navigation        
                                            instruments.                
25.1307.......................     25-72   Miscellaneous equipment.     
25.1309.......................     25-41   Equipment, systems, and      
                                            installations.              
25.1316.......................     25-80   System lightning protection. 
25.1321.......................     25-41   Arrangement and visibility.  
25.1322.......................     25-38   Warning, caution, and        
                                            advisory lights.            
25.1329.......................     25-46   Automatic pilot system.      
25.1331.......................     25-41   Instruments using a power    
                                            supply.                     
25.1333.......................     25-41   Instrument systems.          
25.1335.......................     25-41   Flight director systems.     
25.1381.......................     25-72   Instrument lights.           
25.1501.......................     25-42   General.                     
25.1529.......................     25-54   Instructions for Continued   
                                            Airworthiness.              
25.1581.......................     25-72   General.                     
25.1583.......................     25-72   Operating limitations.       
------------------------------------------------------------------------

    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 Model 747-SP airplane 
because of novel or unusual design features, 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 
14 CFR Sec. 11.49 after public notice, as required by Secs. 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 International Aviation Services, Ltd. apply at 
a later date for an STC to modify any other model already 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).

Novel or Unusual Design Features

    The Boeing Model 747-SP will incorporate a new electronic flight 
instrument system that performs critical functions. This system may be 
vulnerable to HIRF external to the airplane.

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 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 Boeing Model 747-SP, which require that 
new electrical and electronic systems, such as the EFIS, 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, plus the advent of space and satellite communications, 
couples with electronic command and control of the airplane, the 
immunity of critical digital avionics 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 paragraphs 1, or 2 below:
    1. A minimum threat of 100 volts per meter peak 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 following field 
strengths for the frequency ranges indicated.

------------------------------------------------------------------------
                                                        Peak (V/ Average
                       Frequency                           M)     (V/M) 
------------------------------------------------------------------------
10 KHz-100 KHz........................................       50       50
100 KHz-500 KHz.......................................       60       60
500 KHz-2 MHz.........................................       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-1 GHz.........................................    1,700      170
1 GHz-2 GHz...........................................    5,000      990
2 GHz-4 GHz...........................................    6,680      840
4 HGz-6 GHz...........................................    6,850      310
6 GHz-8 GHz...........................................    3,600      670
8 GHz-12 GHz..........................................    3,500    1,270
12 GHz-18 GHz.........................................    3,500      360
18 GHz-40 GHz.........................................    2,100      750
------------------------------------------------------------------------

Applicability

    As discussed above, these special conditions are applicable to 
Boeing Model 747-SP airplanes modified by International Aviation 
Services, Ltd. Should International Aviation Services, Ltd. apply at a 
later date for a supplemental type certificate to modify any other 
model included on Type Certificate A20WE 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).

[[Page 40429]]

Conclusion

    This action affects only certain design features on Boeing Model 
747-SP airplanes modified by International Aviation Services, Ltd. 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 the special conditions for this airplane 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 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. 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 type certification basis for Boeing Model 747-SP airplanes modified 
by International Aviation Services, Ltd.
    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.
    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 July 17, 1997.
Gary L. Killion,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-19858 Filed 7-28-97; 8:45 am]
BILLING CODE 4910-13-M