[Federal Register Volume 62, Number 230 (Monday, December 1, 1997)]
[Proposed Rules]
[Pages 63624-63625]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-31668]



  Federal Register / Vol. 62, No. 230 / Monday, December 1, 1997 / 
Proposed Rules  

[[Page 63624]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-272-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, -200, and -300 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 747-100, -200, 
and -300 series airplanes. This proposal would require the installation 
of components for the suppression of electrical transients and/or the 
installation of shielding and separation of the electrical wiring of 
the fuel quantity indication system (FQIS). This proposal is prompted 
by testing results, which revealed that excessive energy levels in the 
electrical wiring and probes of the fuel system could be induced by 
electrical transients. The actions specified by the proposed AD are 
intended to prevent electrical transients induced by electromagnetic 
interference (EMI) or electrical short circuit conditions from causing 
arcing of the FQIS electrical wiring or probes in the fuel tank, which 
could result in a source of ignition in the fuel tank.

DATES: Comments must be received by March 3, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-272-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays.
    Information concerning this proposal may be obtained from or 
examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, 
SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Chris Hartonas, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2864; fax (425) 
227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-272-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 97-NM-272-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On July 17, 1996, a Boeing Model 747 series airplane was involved 
in an accident shortly after takeoff from John F. Kennedy International 
Airport in Jamaica, New York. In support of the subsequent accident 
investigation, the FAA participated in testing of the fuel quantity 
indication system (FQIS). Results of that testing revealed that 
excessive energy could be induced by high transient voltage levels in 
the electrical wiring and probes of the fuel system. These excessive 
levels occurred when the wiring of the FQIS was subjected to electrical 
transient testing. These electrical transients may be caused in the 
airplane when switching electrical loads in the wiring adjacent to the 
FQIS wiring.
    The FQIS was tested to determine its performance in accordance with 
airplane electromagnetic interference (EMI) requirements. In this test, 
conductive debris, such as steel wool and lockwire, was used to bridge 
the FQIS probes to simulate debris that has been found during 
inspections of transport category airplanes. Results of this test 
indicated that transient voltage levels induced in the FQIS wiring and 
probes could be in excess of 800 volts, and the resulting energy levels 
in the FQIS wiring and probes could be greater than the energy required 
to ignite fuel vapor inside a fuel tank.
    In addition, recent inspections of the fuel probe wiring in Model 
747 fuel tanks revealed damaged wiring insulation, which exposed the 
conductors inside the fuel tank. This condition, together with the 
introduction of induced transients or short circuit conditions, 
increases the likelihood for potential ignition sources in the fuel 
tank.
    The conditions described above, if not corrected, could result in 
excessive levels of energy in the FQIS wiring and a consequent 
potential source of ignition in the fuel tank.

FAA's Conclusions

    While none of the above conditions have been identified at this 
time as the cause of the accident discussed previously, the FAA 
concludes that results of the tests and inspections that have been 
performed indicate that modifications are required to limit the energy 
level induced in the FQIS wiring and probes. Further, the FAA has 
determined that shielding and separation of the FQIS electrical wiring 
from adjacent wiring is necessary to provide protection from wire-to-
wire electrical short circuit conditions, which are a potential source 
of ignition in the fuel tank.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require the installation of components for the 
suppression of electrical transients and/or the installation of 
shielding and separation of the electrical wiring of the FQIS. The 
actions would be required to be accomplished in accordance with a 
method approved by the FAA.

Cost Impact

    There are approximately 650 Model 747-100, -200, and -300 series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 167

[[Page 63625]]

airplanes of U.S. registry would be affected by this proposed AD.
    Since the manufacturer has not yet developed a modification 
commensurate with the requirements of this proposal, the FAA is unable 
at this time to provide specific information as to the number of work 
hours or the cost of parts that would be required to accomplish the 
proposed modification. A further problem in developing a specific cost 
estimate is the fact that modification costs are expected to vary from 
operator to operator and from airplane to airplane depending upon 
airplane configuration. The proposed compliance time of 12 months 
should provide ample time for the development, approval, and 
installation of an appropriate modification.
    However, based on similar modifications accomplished previously on 
other airplane models, the FAA can reasonably estimate that the 
proposed modification would require 40 work hours to accomplish, at an 
average labor rate of $60 per work hour. The cost of required parts is 
estimated to be $10,000 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$2,070,800, or $12,400 per airplane.
    As indicated earlier in this preamble, the FAA specifically invites 
the submission of comments and other data regarding this economic 
aspect of proposal.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this AD were not adopted.

Regulatory Impact

    The regulations proposed herein would not have substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government. Therefore, in 
accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, will not have a significant economic impact, 
positive or negative, on a substantial number of small entities under 
the criteria of the Regulatory Flexibility Act. A copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting the Rules 
Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

Boeing:  Docket 97-NM-272-AD.

    Applicability: All Model 747-100, -200, and -300 series 
airplanes, certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously. To prevent electrical transients induced by 
electromagnetic interference (EMI) or electrical short circuit 
conditions from causing arcing of the fuel quantity indication 
system (FQIS) electrical wiring or probes in the fuel tank, which 
could result in a source of ignition in the fuel tank, accomplish 
the following:
    (a) Within 12 months after the effective date of this AD, 
install components for the suppression of electrical transients and/
or install shielding and separation of the wiring of the FQIS, in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate.
    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO, FAA. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    Issued in Renton, Washington, on November 26, 1997.
Stewart R. Miller,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-31668 Filed 11-28-97; 10:56 am]
BILLING CODE 4910-13-U