[Federal Register Volume 64, Number 219 (Monday, November 15, 1999)]
[Proposed Rules]
[Pages 61798-61801]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-29742]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-316-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.


[[Page 61799]]


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 767 series 
airplanes. This proposal would require repetitive inspections to detect 
discrepancies of the wiring and surrounding Teflon sleeves of the fuel 
tank boost pumps and override/jettison pumps; replacement of the 
sleeves with new sleeves, for certain airplanes; and repair or 
replacement of the wiring and sleeves with new parts, as necessary. 
This proposal is prompted by reports of chafing of Teflon sleeves that 
surround and protect electrical wires inside conduits installed in the 
fuel tanks. The actions specified by the proposed AD are intended to 
ensure adequate protection to the fuel pump wire insulation. Such 
chafing of the wire insulation could eventually result in exposure of 
electrical conductor, permit arcing from the wire to the conduit, and 
create a potential for a fuel tank fire or explosion.

DATES: Comments must be received by December 30, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 98-NM-316-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: Holly Thorson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-1357; 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-316-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-316-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    Inspections of Boeing Model 747 series airplanes were performed in 
accordance with AD 96-26-06, amendment 39-9870 (62 FR 304, January 3, 
1997), and AD 97-26-07, amendment 39-10250 (62 FR 65352, December 12, 
1997), to detect damage of the sleeving and wire bundles of certain 
fuel tank boost pumps and auxiliary jettison pumps. The inspections 
revealed significant chafing through the Teflon sleeves that enclose 
wire bundles inside the conduits located in the fuel tanks.
    As on Model 747 series airplanes, the Model 767 fuel pumps for the 
main fuel tanks and the center wing tank (auxiliary tank) are supplied 
electrical power by wiring encased in metal conduits inside the fuel 
tanks; a wire bundle is separated from its associated conduit by two 
concentric Teflon sleeves. Moreover, the vibration environments in the 
wing fuel tanks of Model 747 and 767 series airplanes are similar. 
Therefore, the wear rate of the Teflon sleeves surrounding the 
electrical wires could be similar for Model 747 and 767 series 
airplanes.
    Because the unsafe condition identified in AD 96-26-06 and AD 97-
26-07 for Model 747 series airplanes (the potential for fuel tank fire 
or explosion due to chafing) is also likely to occur on Model 767 
series airplanes, procedures were developed (and are described below) 
for the inspection of fuel tank wire bundles and Teflon sleeves on 
Model 767 series airplanes. As part of the validation process for the 
development of the service bulletin for those procedures, the wire 
bundles and sleeves were inspected on several Model 767 series 
airplanes. The inspections revealed numerous cases of chafing through 
the outer Teflon sleeves and three cases of chafing through both Teflon 
sleeves. There were no reports of damage to the wire insulation or 
jacket. Several variations in the sleeve installations were reported, 
including one report of a missing outer sleeve and another report of 
sleeves too thin to meet required criteria. Numerous occurrences of 
spliced sleeve sections were noted; several of those spliced sections 
were separated, leaving 1- to 2-inch gaps in the sleeves and exposing 
the wires. All of the operators that conducted the preliminary 
inspections reported that lacing ties were installed at approximately 
6-inch intervals around the outside of the sleeves. Lacing ties 
installed on the outside of the sleeves (except at the conduit ends) 
may contribute to the degradation of the sleeves. Damaged or spliced 
Teflon sleeves could result in chafing of the electrical wiring in the 
fuel tank conduits and thereby expose the electrical conductor. 
Exposure of the electrical conductor, if not corrected, could permit 
arcing from the wire to the conduit and create a potential for a fuel 
tank fire or explosion.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
767-28A0053, Revision 1, dated August 5, 1999, which describes 
procedures for repetitive visual inspections to detect damage of the 
Teflon sleeves surrounding fuel tank boost pump and override/jettison 
pump wiring; and a follow-on visual inspection to detect damage of the 
wiring and corrective actions, if necessary. The corrective actions 
include replacing discrepant Teflon sleeves (having splices, cuts, 
splits, holes, worn areas, or lacing ties installed on the outside of 
the sleeves) with new Teflon sleeves, replacing wiring that has been 
damaged due to arcing, and repairing or replacing wiring that has been 
damaged for reasons other than arcing. Accomplishment of the actions 
specified in the alert service bulletin is intended to adequately 
address the identified unsafe condition.

[[Page 61800]]

FAA's Findings

    The FAA has determined that splicing the Teflon sleeves at any 
location along the length of the wire bundle is unacceptable because 
spliced sections may pull apart, leaving gaps in the sleeves and 
portions of the wires unprotected from chafing against the conduit. 
Additionally, the FAA has determined that lacing ties installed around 
the sleeves may contribute to the chafing of the sleeves. In light of 
these findings and the demonstrated need for protective Teflon sleeves 
between the wires and the conduits inside the fuel tanks, the FAA has 
concluded that an inspection of all Model 767 series airplanes is 
required to determine the integrity of the installed Teflon sleeves and 
wire bundles.

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 alert service bulletin described previously, except as discussed 
below. The proposed AD also would require that operators report 
positive inspection findings (findings of discrepancies only) to the 
FAA.

Differences Between Proposed AD and Relevant Service Information

    Operators should note that, while Boeing Alert Service Bulletin 
767-28A0053 limits its effectivity to Boeing Model 767 series airplanes 
having certain line numbers, this proposed AD would be applicable to 
all Model 767 series airplanes. The FAA has determined that all Model 
767 series airplanes are subject to the unsafe condition.

Clarification of Service Bulletin Figure

    The FAA finds it necessary to clarify the note inserted between 
steps 6 and 7 in Figure 2, Sheet 4, of the alert service bulletin. 
Where the alert service bulletin refers to ``damage'' as ``more than 
one piece of sleeve,'' this type of ``damage'' is intended to refer to 
splices in the protective Teflon sleeves. Splices are considered 
``damage'' because they may become pulled apart, potentially exposing 
the underlying wires and leaving them unprotected from chafing against 
the conduit.

Cost Impact

    There are approximately 716 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 253 airplanes of U.S. registry 
would be affected by this proposed AD. It would take approximately 5 
work hours per airplane (for airplanes with jettison pumps) or 3 work 
hours per airplane (for airplanes without jettison pumps) to accomplish 
the proposed inspection/replacement, at an average labor rate of $60 
per work hour. Parts, if required, would cost $336 for the sleeve 
replacement proposed by this AD.
    Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be $636 or $516 per airplane, if required to 
accomplish the replacement action; and $300 or $180 per airplane, per 
inspection 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-316-AD.

    Applicability: All Model 767 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 
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 (e) 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 exposure of the electrical conductor, which could 
permit arcing from the wire to the conduit and create a potential 
for a fuel tank fire or explosion, accomplish the following:

Inspection

    1(a) Perform a detailed visual inspection to detect 
discrepancies--including the presence of splices, cuts, splits, 
holes, worn areas, and lacing ties installed on the outside of the 
sleeves (except at the sleeve ends) of the Teflon sleeves 
surrounding the wiring of the fuel tank boost pumps and override/
jettison pumps, at the earlier of the times specified in paragraphs 
(a)(1) and (a)(2) of this AD, in accordance with Boeing Alert 
Service Bulletin 767-28A0053, Revision 1, dated August 5, 1999. 
Repeat the inspection thereafter at intervals not to exceed 60,000 
flight hours or 30,000 flight cycles, whichever occurs first.
    (1) Prior to the accumulation of 50,000 total flight hours, or 
within 90 days after the effective date of this AD, whichever occurs 
later.
    (2) Within 18 months after the effective date of this AD.

    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.''

[[Page 61801]]

Corrective Actions

    (b) If any discrepancy is detected during any inspection 
required by paragraph (a) of this AD: Prior to further flight, 
remove the Teflon sleeves and perform a detailed visual inspection 
to detect damage of the wiring, in accordance with paragraph D. of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
767-28A0053, Revision 1, dated August 5, 1999.
    (1) If no damage to the wiring is detected, prior to further 
flight, install new Teflon sleeves in accordance with the alert 
service bulletin.
    (2) If any damage to the wiring is detected, prior to further 
flight, accomplish the requirements of paragraph (c) of this AD.
    (c) If any damage to the wiring is detected during any 
inspection required by paragraph (b) of this AD: Prior to further 
flight, perform a detailed visual inspection to determine if the 
wiring damage was caused by arcing, in accordance with paragraph D. 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
767-28A0053, Revision 1, dated August 5, 1999.
    (1) If the wire damage was not caused by arcing: Prior to 
further flight, repair any damaged wires or replace the wires with 
new or serviceable wires, as applicable, and install new Teflon 
sleeves; in accordance with the alert service bulletin.
    (2) If any damage caused by arcing is found: Prior to further 
flight, perform an inspection for signs of fuel inside the conduit 
or on the wires, in accordance with the alert service bulletin.
    (i) If no sign of fuel is found, accomplish the actions 
specified by paragraphs (c)(2)(i)(A), (c)(2)(i)(B), (c)(2)(i)(C), 
and (c)(2)(i)(D) of this AD.
    (A) Prior to further flight, repair the wires or replace the 
wires with new or serviceable wires, as applicable, in accordance 
with the alert service bulletin.
    (B) Prior to further flight, install new Teflon sleeves, in 
accordance with the alert service bulletin.
    (C) Repeat the inspection for signs of fuel inside the conduit 
thereafter at intervals not to exceed 500 flight hours, until the 
requirements of paragraph (c)(2)(i)(D) have been accomplished. If 
any fuel is found inside the conduit during any inspection required 
by this paragraph, prior to further flight, replace the conduit with 
a new or serviceable conduit in accordance with the alert service 
bulletin. Thereafter, repeat the inspection specified in paragraph 
(a) at intervals not to exceed 60,000 flight hours or 30,000 flight 
cycles, whichever occurs first.
    (D) Within 6,000 flight hours or 18 months after the initial 
fuel inspection specified by paragraph (c)(2) of this AD, whichever 
occurs first, replace the conduit with a new or serviceable conduit, 
in accordance with the alert service bulletin. Such conduit 
replacement constitutes terminating action for the repetitive fuel 
inspections required by paragraph (c)(2)(i)(C) of this AD.
    (ii) If any fuel is found in the conduit or on any wire: Prior 
to further flight, replace the conduit with a new or serviceable 
conduit, replace damaged wires with new or serviceable wires, and 
install new Teflon sleeves; in accordance with the alert service 
bulletin. Thereafter, repeat the inspection specified in paragraph 
(a) at intervals not to exceed 60,000 flight hours or 30,000 flight 
cycles, whichever occurs first.

Pump Retest

    (d) For any wire bundle removed and reinstalled during any 
inspection required by this AD: Prior to further flight after such 
reinstallation, retest the fuel pump in accordance with paragraph 
G., H., I., or J., as applicable, of the Accomplishment 
Instructions, of Boeing Alert Service Bulletin 767-28A0053, Revision 
1, dated August 5, 1999.

Reporting Requirement

    (e) Submit a report of positive inspection findings (findings of 
discrepancies only), along with any damaged wiring and sleeves, to 
the Seattle Manufacturing Inspection District Office (MIDO), 2500 
East Valley Road, Suite C-2, Renton, Washington 98055-4056; fax 
(425) 227-1159; at the applicable time specified in paragraph (e)(1) 
or (e)(2) of this AD. The report must include the airplane serial 
number; the number of total flight hours and flight cycles on the 
airplane; the location of the electrical cable on the airplane; and 
a statement indicating whether any wire has ever been removed and 
inspected during maintenance, along with the date (if known) of any 
such inspection. Information collection requirements contained in 
this regulation have been approved by the Office of Management and 
Budget (OMB) under the provisions of the Paperwork Reduction Act of 
1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control 
Number 2120-0056.
    (1) For airplanes on which the initial inspection required by 
paragraph (a) of this AD is accomplished after the effective date of 
this AD: Submit the report within 10 days after performing the 
initial inspection.
    (2) For airplanes on which the initial inspection required by 
paragraph (a) of this AD has been accomplished prior to the 
effective date of this AD: Submit the report for the initial 
inspection within 10 days after the effective date of this AD.

Alternative Methods of Compliance

    (f) 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

    (g) 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 5, 1999.
N. B. Martenson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-29742 Filed 11-12-99; 8:45 am]
BILLING CODE 4910-13-P