[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
