[Federal Register Volume 64, Number 148 (Tuesday, August 3, 1999)]
[Proposed Rules]
[Pages 42050-42052]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19810]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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Federal Register / Vol. 64, No. 148 / Tuesday, August 3, 1999 /
Proposed Rules
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-271-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 757 Series Airplanes
Equipped with Rolls Royce Engines
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 certain Boeing Model 757 series
airplanes. This proposal would require repetitive inspections to detect
wire chafing of the left and right engine fuel shutoff valve wire
bundles at Power Plant Station 278 on each engine strut, and repair if
necessary. This proposal would also require repetitive replacement of
three wire support brackets with improved wire support brackets. This
proposal is prompted by reports that such wire support brackets failed
due to fatigue, which subsequently caused the fuel shutoff valve wire
to chafe and to experience a short circuit. The actions specified by
the proposed AD are intended to prevent such conditions, which could
result in either the possible ignition of fuel vapors in a flammable
leakage zone or in the inability to stop the flow of fuel in the event
of an engine fire.
DATES: Comments must be received by September 17, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 8-NM-271-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.
The service information referenced in the proposed rule may be
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Stephen S. Oshiro, 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) 227-2793; 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 98-NM-271-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-114, Attention: Rules
Docket No. 98-NM-271-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports indicating that one operator has
experienced several incidents of ``tripped'' circuit breakers. These
circuit breakers are part of the electrical circuit that controls the
activation of the engine fuel shutoff valves. Later investigation
revealed that the brackets that support the engine fuel shutoff valve
wire bundle had failed due to fatigue. The bracket failures allowed a
fuel shutoff wire bundle to chafe against the hole through which the
wire bundle passes. The chafing of the wire bundle eventually resulted
in exposure of an electrical conductor. This in turn led to a short
circuit, after which the affected engine fuel valve shutoff circuit
became disabled. The brackets are located at Power Plant Station 278,
which is located in an area of the strut that is considered to be a
``flammable leakage zone.'' This condition, if not corrected, could
result in either the possible ignition of fuel vapors in a flammable
leakage zone or in the inability to stop the flow of fuel in the event
of an engine fire.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 757-54-
0013, Revision 3, dated October 23, 1997, which describes procedures
for repetitive inspections of the wire support brackets to detect
fatigue cracking, and corrective actions if necessary. The service
bulletin also describes procedures for replacing the existing brackets
with new, improved brackets. Such replacement would eliminate the need
to continue performing the repetitive inspections specified above.
Accomplishment of the actions specified in the service bulletin is
intended to adequately address the identified unsafe condition.
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 accomplishment of the actions specified in
the service bulletin described previously, except as discussed below.
[[Page 42051]]
Differences Between Proposed Rule and Service Bulletin
Operators should note that the service bulletin does not specify
compliance times for accomplishing the initial and repeat inspections
of the wire support brackets, nor does it specify a compliance time for
replacing these brackets. The FAA has determined that a 12-month
initial inspection compliance time and a repetitive inspection interval
that is not to exceed 12 months would address the identified unsafe
condition in a timely manner. In developing an appropriate compliance
time for this AD, the FAA considered not only the manufacturer's
recommendation, but the degree of urgency associated with addressing
the subject unsafe condition, the average utilization of the affected
fleet, and the time necessary to perform the modification.
In addition, Boeing has failed to establish the expected fatigue
life of the new, improved wire support brackets to the FAA's
satisfaction. The brackets installed per Revision 3 to the service
bulletin are the latest of three designs, each of which was intended to
correct the problem of bracket failure. However, both of the two
previous bracket designs installed per earlier revisions to the service
bulletin also proved to be susceptible to fatigue failure. Thus,
because this design feature was historically prone to failure, this
proposed AD would require that the wire support brackets installed in
accordance with Revision 3 of the service bulletin be replaced at 12-
month intervals--i.e., at the same time the wire bundles are inspected.
This interval is shorter than the actual life of the previously failed
brackets.
Operators also should note that this proposed AD would require
operators to replace all three wire support brackets on each strut of
all affected airplanes, whereas the service bulletin recommends that
operators replace brackets on only certain airplanes. The proposed AD
would require more replacements because the expected fatigue life of
the bracket is not well established.
Finally, operators should note that, for the reason given above,
this proposed AD would require inspections of the wire bundles that
pass through the three wire support brackets on each strut to detect
wire chafing, whereas the service bulletin recommends inspection only
if a wire support bracket is cracked or broken.
Cost Impact
There are approximately 501 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 249 airplanes of U.S. registry
would be affected by this proposed AD.
It would take approximately 6 work hours per airplane to accomplish
the proposed replacement and approximately 2 work hours to accomplish
the proposed inspection. The average labor rate is estimated to be $60
per work hour. Required parts would cost approximately $525 per
airplane per replacement cycle. Based on these figures, the cost impact
of the proposed AD on U.S. operators is estimated to be $250,245, or
$1,005 per airplane, per inspection/replacement cycle.
The cost impact figures discussed above are 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 98-NM-271-AD.
Applicability: Model 757 series airplanes equipped with Rolls
Royce engines, certificated in any category.
Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
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 (d) 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 a short circuit that could result in either the
possible ignition of fuel vapors in a flammable leakage zone or in
the inability to stop the flow of fuel in the event of an engine
fire, accomplish the following:
Corrective Action
(a) Within 12 months after the effective date of this AD,
accomplish paragraphs (a)(1) and (a)(2) of this AD. Thereafter,
repeat paragraphs (a)(1) and (a)(2) at intervals not to exceed 12
months.
(1) Accomplish a detailed visual inspection of the wire bundles
that pass through the three wire support brackets located at Power
Plant Station (PPS) 278 on each engine strut, to detect wire
chafing.
Note 2: For the purposes of this AD, a detailed visual
inspection is defined as: ``An intensive visual examination of a
specific structural area, system, installation or assembly to detect
damage, failure, or irregularity. Available lighting is normally
supplemented with a direct source of good lighting at intensity
deemed appropriate by the inspector. Inspection aids such as mirror,
magnifying lenses, etc., may be used. Surface cleaning and elaborate
access procedures may be required.''
(2) Replace all three existing wire support brackets located at
PPS 278 on each engine strut with improved wire support brackets, in
accordance with Boeing Service Bulletin 757-54-0013, Revision 3,
dated October 23, 1997.
(b) During any inspection performed in accordance with paragraph
(a) of this AD, if
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any wire bundle is found to be chafed, prior to further flight,
repair the wire bundle in accordance with the Boeing Standard Wiring
Practices Manual, Document D6-54446, Revision 23, dated August 1998.
Spares Paragraph
(c) As of the effective date of this AD, no person shall install
a wire support bracket having P/N 287N1112-8, -9, -20, or -21 on any
airplane.
Alternative Methods of Compliance
(d) 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 Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
Special Flight Permits
(e) 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 July 27, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-19810 Filed 8-2-99; 8:45 am]
BILLING CODE 4910-13-P
