[Federal Register Volume 64, Number 195 (Friday, October 8, 1999)]
[Rules and Regulations]
[Pages 54763-54767]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-25930]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-318-AD; Amendment 39-11360; AD 99-21-15]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
and -500 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to all Boeing Model 737-100, -200, -300, -400, and -
500 series airplanes, that currently requires removal of the fuel boost 
pump wiring in the conduits of the wing and center fuel tanks; an 
inspection to detect damage of the wiring, and corrective action, if 
necessary; and eventual installation of Teflon sleeving over the 
electrical cable. This amendment expands the inspection requirement to 
include airplanes with fewer than 20,000 flight hours; requires 
additional repetitive inspections for all airplanes; reidentifies the 
requirement to install Teflon sleeving as a nonterminating action; and 
removes the requirement to report inspection results. This amendment is 
prompted by the FAA's determination that Model 737-100 through -500 
series airplanes that are not affected by the current AD must also be 
protected against excessive wire chafing of the fuel boost pump wiring 
and that all Model 737-100 through -500 series airplanes must be 
repetitively inspected. The actions specified by this AD are intended 
to detect and correct chafing and prevent electrical arcing between the 
fuel boost pump wiring and the surrounding conduit, which could result 
in arc-through of the conduit, and consequent fire or explosion of the 
fuel tank.

DATES: Effective November 12, 1999.
    The incorporation by reference of Boeing Service Bulletin 737-
28A1120, Revision 2, dated November 26, 1998, as listed in the 
regulations, is approved by the Director of the Federal Register as of 
November 12, 1999.
    The incorporation by reference of Boeing Alert Service Bulletin 
737-28A1120, Revision 1, dated May 28, 1998, as listed in the 
regulations, was approved previously by the Director of the Federal 
Register as of October 15, 1998 (63 FR 52152, September 30, 1998).
    The incorporation by reference of Boeing Alert Service Bulletin 
737-28A1120, dated April 24, 1998, as revised by Notices of Status 
Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 
03, dated May 9, 1998; as listed in the regulations; was approved 
previously by the Director of the Federal Register as of June 29, 1998 
(63 FR 34271, June 24, 1998).

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of

[[Page 54764]]

the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Dorr Anderson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2684; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 98-19-09, 
amendment 39-10751 (63 FR 52152, September 30, 1998), which is 
applicable to all Boeing Model 737-100, -200, -300, -400, and -500 
series airplanes, was published in the Federal Register on January 11, 
1999 (64 FR 1545). The action proposed to continue to require removal 
of the fuel boost pump wiring in the conduits of the wing and center 
fuel tanks; an inspection to detect damage of the wiring, and 
corrective action, if necessary; and eventual installation of Teflon 
sleeving over the electrical cable. The action also proposed to expand 
the inspection requirement to include additional airplanes, add 
repetitive inspections for all airplanes, and reidentify the 
requirement to install Teflon sleeving as a nonterminating action.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    Three commenters, including the airplane manufacturer, support the 
requirement of initial inspection of the fuel boost pump wiring 
specified in paragraph (f) of the proposed rule.
    Three commenters, including the airplane manufacturer, support the 
requirement of repetitive inspections of the fuel boost pump wiring 
specified in paragraph (g) and reidentification of the requirement to 
install Teflon sleeving as a nonterminating action specified in 
paragraphs (h) through (k) of the proposed rule.

Requests to Revise Requirements for Certain Airplanes

    One commenter, the airplane manufacturer, requests that the 
applicability for the initial inspection of the fuel boost pump wiring 
specified in paragraph (f) of the proposed AD be limited to airplanes 
having line numbers 1 through 3072 inclusive. The commenter states that 
airplanes having line numbers 3073 and subsequent were delivered with 
the Teflon sleeving specified in paragraphs (h) through (k) of the 
proposed AD already installed. The FAA concurs with the commenter's 
request and has revised paragraph (f) of the final rule accordingly. 
Airplanes having line numbers 3073 and subsequent still require 
repetitive inspections of the fuel boost pump wiring at intervals not 
to exceed 30,000 flight hours as specified in paragraph (g) of the AD. 
Therefore, paragraph (f) of the final rule has also been revised to 
require an initial inspection of the fuel boost pump wiring prior to 
the accumulation of 30,000 total flight hours for those airplanes.
    One commenter requests that the applicability for the repetitive 
inspections of the fuel boost pump wiring specified in paragraph (g) of 
the proposed AD include airplanes inspected in accordance with 
paragraphs (a), (b), and (c) of the proposed AD. The FAA concurs that 
airplanes inspected in accordance with paragraphs (a), (b), and (c) of 
this AD must be subject to the repetitive inspections specified in 
paragraph (g). However, by including reference to paragraph (d) in 
paragraph (g) of this AD, all airplanes that have accumulated more than 
30,000 total flight hours are already included. The reference in 
paragraph (g) of this AD to paragraphs (e) and (f) includes all other 
airplanes. Therefore, paragraph (g) of this AD requires repetitive 
inspections of the fuel boost pump wiring for all Model 737-100, -200, 
-300, -400, and -500 series airplanes. No change to the final rule is 
necessary in this regard.

Request for Alternative Corrective Action

    One commenter requests that paragraph (l) of the proposed AD be 
revised to allow removal of the case ground wire in lieu of replacement 
of the case ground wire with a new wire. The commenter states that 
Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated May 28, 
1998, and Boeing Service Bulletin 737-28A1120, Revision 2, dated 
November 26, 1998, allow removal of the case ground wire as an 
alternative to replacement of the case ground wire with a new wire. The 
FAA concurs and has revised paragraph (l) of the final rule 
accordingly.

Request to Eliminate the Repetitive Inspections

    Two commenters request that the repetitive inspections of the fuel 
boost pump wiring specified in paragraph (g) of the proposed AD be 
eliminated. One commenter states that, because the repetitive 
inspections apply to the electrical cable with the Teflon sleeving 
installed, use of the findings from the initial inspection of the fuel 
boost pump wiring, which did not have the Teflon sleeving installed, to 
determine the interval for the repetitive inspections is without merit. 
This commenter requests that the FAA eliminate the proposed repetitive 
inspections, and instead, perform tests of the electrical cable with 
the Teflon sleeving installed to determine the resistance of the fuel 
boost pump wiring to chafing. The commenter states that only after 
thorough testing and examination of the data should the FAA determine 
whether repetitive inspections of the fuel boost pump wiring are 
necessary. The other commenter states that it has reviewed the data 
made public by the FAA with the findings from the initial inspection of 
the fuel boost pump wiring, and concludes that installation of Teflon 
sleeving over the electrical cable improves the durability of the 
wiring sufficiently to be considered terminating action. This commenter 
requests that, if the FAA determines that repetitive inspections of the 
fuel boost pump wiring are necessary, the interval be a minimum of 
60,000 flight hours. In addition, both commenters express concern that 
wire bundle removal and installation can cause damage which may induce 
an unsafe condition that would not otherwise be present.
    The FAA does not concur with the commenters' request. The FAA has 
determined that 30,000 flight hours represents an appropriate interval 
of time for the repetitive inspections of the fuel boost pump wiring 
specified in paragraph (g) of this AD wherein an acceptable level of 
safety can be maintained. The FAA finds that the conduit-enclosed fuel 
boost pump wiring installation is not a fail-safe design. Therefore, 
repetitive inspections are necessary to ensure safe operation. This 
decision is supported by the testing conducted by the airplane 
manufacturer, and the findings from the inspections of the fuel boost 
pump wiring. In addition, the FAA recognizes that the fuel boost pump 
wiring may be damaged upon removal from and installation into the 
conduit. However, damage upon removal is readily detectable and a 
damaged wire will not be reinstalled into the airplane. The FAA also 
notes that the addition of the Teflon sleeving prior to installation of 
the wiring greatly reduces the possibility of installation damage. The 
sleeving allows the wiring to translate in the conduit with less 
friction than without sleeving, resulting in less force being required 
to pull the wiring

[[Page 54765]]

through the conduit. Therefore, the FAA concludes that the hazard 
introduced by removal and installation of the wiring is minimal 
relative to the hazard of not re-inspecting at all. No change to the 
final rule is necessary in this regard.

Request for Reduction of Repetitive Inspection Interval

    One commenter requests that the interval for the repetitive 
inspections of the fuel boost pump wiring specified in paragraph (g) of 
the proposed AD be reduced from 30,000 flight hours to 20,000 flight 
hours. The commenter assumes that the compliance threshold of 20,000 
flight hours for the initial inspection of the fuel boost pump wiring 
represents the ``safe life'' of the wiring. The commenter then states 
that there appears to be no justification for the interval of 30,000 
flight hours for the repetitive inspections of the fuel boost pump 
wiring, and that it would be logical for the compliance thresholds for 
the initial and repetitive inspections to be the same.
    The FAA does not concur with the commenter's request. Paragraphs 
(d) through (f)(1) of the final rule require an initial inspection of 
the fuel boost pump wiring for all airplanes that do not have Teflon 
sleeving installed over the electrical cable, at various times, but no 
later than 24 months after the effective date of this AD. For some 
airplanes, the initial inspection will occur substantially earlier than 
20,000 total flight hours. The compliance time for the initial 
inspection is not meant to be representative of the ``safe life'' of 
the wiring. The FAA notes that the wiring configuration is changed by 
adding Teflon sleeving over the electrical cable, in accordance with 
paragraphs (h) through (k) of this AD, between the initial inspection 
specified in paragraphs (d) through (f)(1) and the repetitive 
inspections specified in paragraph (g). The additional sleeving 
increases the amount of insulation around the conductor by 
approximately 33 percent. In developing an appropriate compliance time 
for the repetitive inspections, the FAA considered the recommendation 
of the airplane manufacturer and testing conducted by the airplane 
manufacturer to substantiate the selected interval. In consideration of 
these items, as well as the findings from the inspection of the fuel 
boost pump wiring, the FAA has determined that 30,000 flight hours 
represents an appropriate interval of time for the repetitive 
inspections of the fuel boost pump wiring specified in paragraph (g) of 
this AD wherein an acceptable level of safety can be maintained. No 
change to the final rule is necessary in this regard.

Request for Information on Terminating Action

    One commenter requests information regarding development of 
terminating action for the repetitive inspections specified in 
paragraph (g) of the proposed AD. The commenter states that, although 
this AD addresses the immediate problem of chafing of the fuel boost 
pump wiring, no information is provided that defines the root cause of 
the chafing, such as vibration, and possible terminating action for the 
repetitive inspections. No specific change to the rule is requested.
    The FAA agrees that the actions specified in this AD do not address 
the root cause of the chafing of the fuel boost pump wiring; however, 
the FAA has determined that installation of the Teflon sleeving and the 
repetitive inspections address the stated unsafe condition. If the 
airplane manufacturer chooses to conduct testing to identify the root 
cause of the chafing and recommends additional design modifications, 
the FAA will give those due consideration. However, the FAA, as well as 
the manufacturer, recognizes that the hazards associated with obtaining 
sufficient data may outweigh the benefits of further testing. Such 
testing could require installation of electrical equipment inside the 
fuel tank to monitor conduit vibration, which may present an additional 
ignition source inside the tank, substantially increasing risk to test 
personnel and testing fixtures. No change to the final rule is 
necessary in this regard.

Explanation of Additional Change to the Proposal

    The requirements to submit damaged electrical cables and conduits 
to the manufacturer and report results of the initial inspection to the 
FAA have been eliminated from this final rule. In the preamble to AD 
98-19-09, the FAA indicated that it was considering further rulemaking 
action to require inspection of Model 737 series airplanes that have 
accumulated fewer than 20,000 total flight hours. The reporting 
requirements were intended to allow the manufacturer and the FAA to 
determine the extent of wiring damage in the affected fleet in order to 
consider further rulemaking action. As stated in the NPRM, this AD 
follows from the determination that further rulemaking action is 
necessary. The FAA has determined that sufficient data have been 
collected, and no additional data is necessary. Therefore, the 
reporting requirements included in paragraph (m) of the proposal are 
not included in this final rule.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes described 
previously. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 2,866 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,131 airplanes of U.S. 
registry will be affected by this AD.
    The inspection that is currently required by AD 98-19-09, and 
retained in this AD, takes approximately 30 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. This new AD 
action will require repetitive performance of that inspection. Based on 
these figures, the cost impact of the currently required inspection on 
U.S. operators is estimated to be $2,035,800, or $1,800 per airplane, 
per inspection cycle.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the 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 adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) Is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules

[[Page 54766]]

Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends 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 removing amendment 39-10751 (63 FR 
52152, September 30, 1998), and by adding a new airworthiness directive 
(AD), amendment 39-11360, to read as follows:

99-21-15  BOEING: Amendment 39-11360. Docket 98-NM-318-AD. 
Supersedes AD 98-19-09, Amendment 39-10751.

    Applicability: All Model 737-100, -200, -300, -400, and -500 
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 (m)(1) 
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 detect and correct chafing and prevent electrical arcing 
between the fuel boost pump wiring and the surrounding conduit, 
which could result in arc-through of the conduit, and consequent 
fire or explosion of the fuel tank, accomplish the following:

Inspections Required by AD 98-11-52

    (a) For all airplanes that have accumulated 50,000 or more total 
flight hours as of June 29, 1998 (the effective date of AD 98-11-52, 
amendment 39-10611): Prior to further flight, remove the fuel boost 
pump wiring from the in-tank conduit for the aft boost pumps in main 
tanks numbers 1 and 2, and perform a detailed visual inspection to 
detect damage of the wiring, in accordance with the procedures 
specified in Boeing Alert Service Bulletin 737-28A1120, dated April 
24, 1998, as revised by Notices of Status Change NSC 01, dated May 
7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998; 
Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated May 28, 
1998; or Boeing Service Bulletin 737-28A1120, Revision 2, dated 
November 26, 1998.
    (b) For all airplanes that have accumulated less than 50,000 
total flight hours as of receipt of telegraphic AD T98-11-51: Prior 
to the accumulation of 40,000 total flight hours, or within 14 days 
after June 29, 1998, whichever occurs later, remove the fuel boost 
pump wiring from the in-tank conduit for the aft boost pumps in main 
tanks numbers 1 and 2, and perform a detailed visual inspection to 
detect damage of the wiring, in accordance with the procedures 
specified in Boeing Alert Service Bulletin 737-28A1120, dated April 
24, 1998, as revised by Notices of Status Change NSC 01, dated May 
7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998; 
Revision 1, dated May 28, 1998; or Revision 2, dated November 26, 
1998.
    (c) For all airplanes: Remove the fuel boost pump wiring from 
the in-tank conduit for the center tank left and right boost pumps, 
and perform a detailed visual inspection to detect damage of the 
wiring, in accordance with the procedures specified in Boeing Alert 
Service Bulletin 737-28A1120, dated April 24, 1998, as revised by 
Notices of Status Change NSC 01, dated May 7, 1998, NSC 02, dated 
May 8, 1998, and NSC 03, dated May 9, 1998; Revision 1, dated May 
28, 1998; or Revision 2, dated November 26, 1998. Accomplish the 
inspection at the earliest of the times specified in paragraphs 
(c)(1), (c)(2), and (c)(3).
    (1) For Model 737-300, -400, and -500 series airplanes: Inspect 
prior to the accumulation of 40,000 total flight hours, or within 14 
days after June 29, 1998, whichever occurs later.
    (2) For Model 737-100 and -200 series airplanes: Inspect prior 
to the accumulation of 40,000 total flight hours, or within 10 days 
after June 29, 1998, whichever occurs later.
    (3) For all airplanes: Inspect prior to the accumulation of 
50,000 total flight hours, or within 5 days after June 29, 1998, 
whichever occurs later.
    (d) For all airplanes: Prior to the accumulation of 30,000 total 
flight hours or within 45 days after June 29, 1998, whichever occurs 
later, remove the fuel boost pump wiring from the in-tank conduit 
for the aft boost pumps in main tanks numbers 1 and 2, and the 
center tank left and right boost pumps, and perform a detailed 
visual inspection to detect damage of the wiring, in accordance with 
the procedures specified in Boeing Alert Service Bulletin 737-
28A1120, dated April 24, 1998, as revised by Notices of Status 
Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 
03, dated May 9, 1998; Revision 1, dated May 28, 1998; or Revision 
2, dated November 26, 1998.

Inspections Required by AD 98-19-09

    (e) For airplanes that have accumulated 20,000 or more total 
flight hours and less than 30,000 total flight hours as of October 
15, 1998 (the effective date of AD 98-19-09, amendment 39-10751): 
Within 60 days after October 15, 1998, remove the fuel boost pump 
wiring from the in-tank conduit for the aft boost pumps in main 
tanks numbers 1 and 2, and the center tank left and right boost 
pumps, and perform a detailed visual inspection to detect damage of 
the wiring; in accordance with the procedures specified in Boeing 
Alert Service Bulletin 737-28A1120, dated April 24, 1998, as revised 
by Notices of Status Change NSC 01, dated May 7, 1998, NSC 02, dated 
May 8, 1998, and NSC 03, dated May 9, 1998; Revision 1, dated May 
28, 1998; or Revision 2, dated November 26, 1998.

New Inspection Requirements

    (f) Remove the fuel boost pump wiring from the in-tank conduit 
for the aft boost pumps in main tanks numbers 1 and 2, and the 
center tank left and right boost pumps, and perform a detailed 
visual inspection to detect damage of the wiring; at the time 
specified in paragraphs (f)(1) and (f)(2) of this AD, as applicable. 
Perform these actions in accordance with the procedures specified in 
Boeing Alert Service Bulletin 737-28A1120, dated April 24, 1998, as 
revised by Notices of Status Change NSC 01, dated May 7, 1998, NSC 
02, dated May 8, 1998, and NSC 03, dated May 9, 1998; Boeing Alert 
Service Bulletin 737-28A1120, Revision 1, dated May 28, 1998; or 
Boeing Service Bulletin 737-28A1120, Revision 2, dated November 26, 
1998.
    (1) For airplanes having line numbers 1 through 3072 inclusive 
that have accumulated less than 20,000 total flight hours as of 
October 15, 1998: Inspect at the earlier of the times specified in 
paragraph (f)(1)(i) and (f)(1)(ii) of this AD.
    (i) Prior to the accumulation of 20,000 total flight hours, or 
within 60 days after the effective date of this AD, whichever occurs 
later.
    (ii) Within 24 months after the effective date of this AD.
    (2) For airplanes having line numbers 3073 and subsequent: 
Inspect prior to the accumulation of 30,000 total flight hours.
    (g) For all airplanes: Repeat the inspection required by 
paragraph (d), (e), or (f) of this AD, as applicable, at intervals 
not to exceed 30,000 flight hours after initial accomplishment of 
the applicable inspection.

Corrective Actions

    (h) If red, yellow, blue, or green wire insulation cannot be 
seen through the outer jacket of the electrical cable during any 
inspection required by this AD: Prior to further flight, accomplish 
paragraph (h)(1), (h)(2), or (h)(3) of this AD in accordance with 
procedures specified in Boeing Alert Service Bulletin 737-28A1120, 
dated April 24, 1998, as revised by Notices of Status Change NSC 01, 
dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 
9, 1998; Revision 1, dated May 28, 1998; or Revision 2, dated 
November 26, 1998.
    (1) Install Teflon sleeving over the electrical cable, and 
reinstall the cable. Or
    (2) Reinstall the electrical cable without Teflon sleeving over 
the cable. Within 500 flight hours after accomplishment of the 
reinstallation, repeat the inspection

[[Page 54767]]

described in paragraph (d), (e), or (f) of this AD, as applicable, 
and install Teflon sleeving over the cable. Or
    (3) Replace the electrical cable with new cable without Teflon 
sleeving. Within 18 months or 6,000 flight hours, whichever occurs 
first, repeat the inspection specified in paragraph (d), (e), or (f) 
of this AD, as applicable, and install Teflon sleeving over the 
cable.
    (i) If red, yellow, blue, or green wire insulation can be seen 
through the outer jacket of the electrical cable during any 
inspection required by this AD, but no evidence of electrical arcing 
is found: Prior to further flight, accomplish either paragraph 
(i)(1) or (i)(2) of this AD in accordance with the procedures 
specified in Boeing Alert Service Bulletin 737-28A1120, dated April 
24, 1998, as revised by Notices of Status Change NSC 01, dated May 
7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 1998; 
Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated May 28, 
1998; or Boeing Service Bulletin 737-28A1120, Revision 2, dated 
November 26, 1998.
    (1) Replace the damaged electrical cable with a new cable, 
install Teflon sleeving over the cable, and reinstall the cable. Or
    (2) Replace the electrical cable with a new cable without Teflon 
sleeving. Within 18 months or 6,000 flight hours, whichever occurs 
first, repeat the inspection described in paragraph (d), (e), or (f) 
of this AD, as applicable, and install Teflon sleeving over the 
cable.
    (j) If any evidence of electrical arcing but no evidence of fuel 
leakage is found on the removed electrical cable during any 
inspection required by this AD: Prior to further flight, accomplish 
paragraphs (j)(1) and (j)(2) of this AD in accordance with the 
procedures specified in Boeing Alert Service Bulletin 737-28A1120, 
dated April 24, 1998, as revised by Notices of Status Change NSC 01, 
dated May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 
9, 1998; Boeing Alert Service Bulletin 737-28A1120, Revision 1, 
dated May 28, 1998; or Boeing Service Bulletin 737-28A1120, Revision 
2, dated November 26, 1998.
    (1) Verify the integrity of the conduit in accordance with the 
instructions contained in NSC 03, Revision 1, or Revision 2 of the 
alert service bulletin. And
    (2) Accomplish either paragraph (j)(2)(i) or (j)(2)(ii) of this 
AD in accordance with the alert service bulletin.
    (i) Replace the damaged electrical cable with a new cable, 
install Teflon sleeving over the cable, and reinstall the cable. Or
    (ii) Replace the electrical cable with a new cable without 
Teflon sleeving. Within 18 months or 6,000 flight hours, whichever 
occurs first, repeat the inspection described in paragraph (d), (e), 
or (f) of this AD, as applicable, and install Teflon sleeving over 
the cable.
    (k) If any evidence of fuel is found on the removed electrical 
cable during any inspection required by this AD: Prior to further 
flight, accomplish paragraphs (k)(1) and (k)(2) of this AD in 
accordance with the procedures specified in Boeing Alert Service 
Bulletin 737-28A1120, dated April 24, 1998, as revised by Notices of 
Status Change NSC 01, dated May 7, 1998, NSC 02, dated May 8, 1998, 
and NSC 03, dated May 9, 1998; Boeing Alert Service Bulletin 737-
28A1120, Revision 1, dated May 28, 1998; or Boeing Service Bulletin 
737-28A1120, Revision 2, dated November 26, 1998.
    (1) Replace the conduit section where electrical arcing was 
found. And
    (2) Accomplish either paragraph (k)(2)(i) or (k)(2)(ii) of this 
AD.
    (i) Replace the damaged electrical cable with a new cable, 
install Teflon sleeving over the cable, and reinstall the cable. Or
    (ii) Replace the electrical cable with a new cable without 
Teflon sleeving. Within 18 months or 6,000 flight hours, whichever 
occurs first, repeat the inspection described in paragraph (d), (e), 
or (f) of this AD, as applicable, and install Teflon sleeving over 
the cable.
    (l) For Groups 1 and 2 airplanes, as identified in Boeing Alert 
Service Bulletin 737-28A1120, dated April 24, 1998: Concurrent with 
the first accomplishment of corrective action in accordance with 
paragraph (h), (i), (j), or (k) of this AD, as applicable, replace 
the case ground wire with a new wire or remove the case ground wire 
in accordance with Boeing Alert Service Bulletin 737-28A1120, dated 
April 24, 1998, as revised by Notices of Status Change NSC 01, dated 
May 7, 1998, NSC 02, dated May 8, 1998, and NSC 03, dated May 9, 
1998; Boeing Alert Service Bulletin 737-28A1120, Revision 1, dated 
May 28, 1998; or Boeing Service Bulletin 737-28A1120, Revision 2, 
dated November 26, 1998.

Alternative Methods of Compliance

    (m)(1) 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, 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.
    (m)(2) Alternative methods of compliance, approved previously in 
accordance with AD 98-11-52 and AD 98-19-09, are approved as 
alternative methods of compliance with this AD.

    Note 2: 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

    (n) Special flight permits may be issued in accordance with 
Secs. 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.

Incorporation by Reference

    (o) The actions shall be done in accordance with Boeing Alert 
Service Bulletin 737-28A1120, dated April 24, 1998, as revised by 
Notice of Status Change NSC 01, dated May 7, 1998, Notice of Status 
Change NSC 02, dated May 8, 1998, and Notice of Status Change NSC 
03, dated May 9, 1998; Boeing Alert Service Bulletin 737-28A1120, 
Revision 1, dated May 28, 1998; or Boeing Service Bulletin 737-
28A1120, Revision 2, dated November 26, 1998.
    (1) The incorporation by reference of Boeing Service Bulletin 
737-28A1120, Revision 2, dated November 26, 1998, as listed in the 
regulations, is approved by the Director of the Federal Register as 
of November 12, 1999.
    (2) The incorporation by reference of Boeing Alert Service 
Bulletin 737-28A1120, Revision 1, dated May 28, 1998, was approved 
previously by the Director of the Federal Register as of October 15, 
1998 (63 FR 52152, September 30, 1998).
    (3) The incorporation by reference of Boeing Alert Service 
Bulletin 737-28A1120, dated April 24, 1998, as revised by Notice of 
Status Change NSC 01, dated May 7, 1998, Notice of Status Change NSC 
02, dated May 8, 1998, and Notice of Status Change NSC 03, dated May 
9, 1998, was approved previously by the Director of the Federal 
Register as of June 29, 1998 (63 FR 34271, June 24, 1998).
    (4) Copies may be obtained from Boeing Commercial Airplane 
Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be 
inspected at the FAA, Transport Airplane Directorate, 1601 Lind 
Avenue, SW., Renton, Washington; or at the Office of the Federal 
Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
    (p) This amendment becomes effective on November 12, 1999.

    Issued in Renton, Washington, on September 29, 1999.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-25930 Filed 10-7-99; 8:45 am]
BILLING CODE 4910-13-U