[Federal Register Volume 65, Number 151 (Friday, August 4, 2000)]
[Rules and Regulations]
[Pages 47841-47843]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19841]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM173; Special Conditions No. 25-163-SC]


Special Conditions: Boeing Model 747-2G4B 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 747-2G4B 
series airplanes modified by Boeing Airplane Services. These modified 
airplanes will have novel or unusual design features when compared to 
the state of technology envisioned in the airworthiness standards for 
transport category airplanes. The modification incorporates the 
installation of new Electronic Flight Instrument System (EFIS) 
displays. The EFIS displays will utilize electrical and electronic 
systems that perform 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 July 27, 2000.
    Comments must be received on or before September 5, 2000.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Transport Airplane 
Directorate, Attention: Rules Docket (ANM-114), Docket No. NM173, 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. NM173. Comments may be 
inspected in the Rules Docket weekdays, except Federal holidays, 
between 7:30 a.m. and 4 p.m.

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 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 or 
notice 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 received 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. 
Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must include a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. NM173.'' The postcard will be date stamped and returned 
to the commenter.

Background

    On August 25, 1997, Boeing Airplane Services, Wichita Division, 
P.O. Box 7730, Wichita, KS 67277-7730, applied for a Supplemental Type 
Certificate (STC) for the Boeing Model 747-2G4B series airplanes. The 
Boeing Model 747-2G4B is a Model 747-200 series airplane with four CF6-
80C2B1 engines. The Model 747-200 series airplanes are an extended 
range passenger version of the Model 747-100 airplanes with changes to 
increase its strength and fuel capacity. The Model 747-2G4B will 
incorporate an Electronic Flight Instrument System (EFIS), which 
displays attitude and heading information and is manufactured by 
Astronautics. The modified airplanes are scheduled for certification in 
November 2000.
    The Astronautics EFIS is a critical function that displays attitude 
and heading information. The EFIS must be designed and installed to 
ensure that their operations are not adversely affected by high 
intensity radiated fields (HIRF). These functions can be susceptible to 
disruption of both command and response signals as a result of 
electrical and magnetic interference caused by HIRF external to the 
airplane. This disruption of signals could result in loss of critical 
flight displays and annunciations, or could present misleading 
information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Boeing Airplane Services 
must show that the Boeing Model 747-2G4B series airplanes, as changed, 
continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. 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 regulations included in the certification 
basis for the Boeing Model 747-2G4B series airplanes include Title 14, 
Code of Federal Regulations (14 CFR) part 25, as amended by Amendments 
25-1 through 25-8, plus additional requirements in Type Certificate 
Data Sheet (TCDS) A20WE.

[[Page 47842]]

    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 747-2G4B 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 747-2G4B series airplanes must comply with 
the fuel vent and exhaust emission requirement of 14 CFR part 34 and 
the noise certification requirement of 14 CFR part 36.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49, as required by Secs. 11.28 and 11.29, and become part of 
the airplane's 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 the applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design features, 
these 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 747-2G4B series airplanes will incorporate the 
Astronautics EFIS system, which performs critical functions. The EFIS 
system contains electronic equipment for which the current 
airworthiness standards (14 CFR part 25) do not contain adequate or 
appropriate safety standards that address protecting this equipment 
from the adverse effects of HIRF. This system may be vulnerable to HIRF 
external to the airplane. Accordingly, this system is considered to be 
a novel or unusual design feature.

Discussion

    There is no specific regulation that addresses the requirements for 
protection of 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 that is equivalent to 
that intended by the regulations incorporated by reference, special 
conditions are needed for the Boeing Model 747-2G4B airplanes modified 
to include the Astronautics EFIS system. These special conditions will 
require that this 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 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 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 following field 
strengths 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 the 
Boeing Model 747-2G4B series airplanes modified by Boeing to include 
the Astronautics EFIS system. Should Boeing Airplane Services 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 features, these special conditions would apply to 
that model as well under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only certain novel or unusual design features 
on the Boeing Model 747-2G4B series airplanes modified by Boeing 
Airplane Services. 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 has been subjected to the 
notice and comment period 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 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

[[Page 47843]]

supplemental type certification basis for the Boeing Model 747-2G4B 
series airplanes modified by Boeing Airplane Services.
    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 July 27, 2000
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19841 Filed 8-3-00; 8:45 am]
BILLING CODE 4910-13-P