AD 2001-20-10

[Federal Register Volume 66, Number 200 (Tuesday, October 16, 2001)]
[Rules and Regulations]
[Pages 52489-52492]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-25616]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-146-AD; Amendment 39-12458; AD 2001-20-10]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 737 series airplanes, that requires 
inspection of wire bundles in certain junction boxes in the main wheel 
well to detect chafing or damage, and follow-on actions. The actions 
specified by this AD are intended to prevent wire damage, which could 
result in arcing

[[Page 52490]]

and consequent fire in the main wheel well or passenger cabin, or 
inability to stop the flow of fuel to an engine or to the auxiliary 
power unit in the event of a fire. This action is intended to address 
the identified unsafe condition.

DATES: Effective November 20, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 20. 2001.

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

FOR FURTHER INFORMATION CONTACT: Stephen Oshiro, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-2793; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 737 series 
airplanes was published as a supplemental notice of proposed rulemaking 
(NPRM) in the Federal Register on June 5, 2001 (66 FR 30114). That 
action proposed to require inspection of wire bundles in four junction 
boxes in the main wheel well to detect chafing or damage, and follow-on 
actions.

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.
    One commenter concurs with the proposed rule; another commenter 
indicates that it is already accomplishing the proposed inspections and 
has no further comments.

Extend Compliance Time

    One commenter asks that we extend the compliance time for the 
proposed requirements from 12 to 18 months after the effective date of 
the AD. The commenter states that the 12-month compliance time is not a 
sufficient amount of time to perform the inspection (check) during its 
737 fleet `C-check' cycle. The assessment was based on the amount of 
operational testing that would have to be performed on the systems that 
would be disturbed by the proposed inspections and modifications. The 
commenter recommends the compliance time be extended to 18 months to 
ensure the inspection may be accomplished during a scheduled 
maintenance visit.
    The FAA agrees to extend the compliance time for the inspection to 
18 months. In developing an appropriate compliance time for the 
inspection required by the final rule, we considered not only the 
degree of urgency associated with addressing the unsafe condition, but 
the practical aspect of accomplishing the inspection of the wire 
bundles on the Model 737 fleet in a timely manner. It is our intent in 
this final rule to allow the inspections to be done within the time 
frame of a regular maintenance interval. We took the commenter's 
recommendations into account, as well as the time necessary to do the 
specified actions, and we find that an 18-month compliance time should 
correspond with the regular maintenance schedules of the majority of 
affected operators. An extension of the compliance time to 18 months 
will not adversely affect safety. Paragraph (a) of the final rule has 
been changed accordingly.
    Two commenters ask that the proposed compliance time be extended to 
24 months. One commenter, the airplane manufacturer, states that, based 
on input from the airlines and an internal Boeing review, the 
compliance time should be extended. The commenter notes that this 
extension will provide adequate time for compliance to operators with 
large fleets because they will be able to accomplish the inspection 
during routine maintenance, rather than scheduling an inspection 
specifically to address the proposed rule. The second commenter states 
that a 24-month compliance time would allow it to accomplish the 
inspections during regularly scheduled maintenance.
    We do not agree to extend the compliance time for the inspection to 
24 months. We have already considered factors such as operators' 
maintenance schedules in setting a compliance time for the required 
modification, and have determined that 18 months is an appropriate 
compliance time in which the inspection may be accomplished during 
scheduled airplane maintenance for the majority of affected operators. 
Since maintenance schedules vary from operator to operator, it would 
not be possible to guarantee that all affected airplanes could be 
modified during scheduled maintenance, even with a compliance time of 
24 months. In any event, we find that 18 months represents the maximum 
time wherein the affected airplanes may continue to operate prior to 
inspection without compromising safety. No further change to the final 
rule is necessary in this regard.

Add New Service Information

    One commenter asks that Boeing Service Letter 737-SL-24-138, dated 
May 24, 1999, be added to the proposed rule as another source of 
service information for accomplishment of certain actions related to 
those specified in the proposed rule. The service letter was referenced 
in a Civil Airworthiness Authorities' Additional Airworthiness 
Directive.
    On July 2, 2001, the FAA issued AD 2001-14-06, amendment 39-12316 
(66 FR 36445, July 12, 2001), which references that service letter as 
the appropriate source of service information for accomplishment of the 
inspections of the circuit connectors of the fuel shutoff valve in the 
main wheel well. As the service letter has been addressed in another 
AD, no change to the final rule is necessary in this regard.

Change Certain Requirements

    One commenter asks that the proposed requirement of wire protection 
features, as specified in paragraph (a)(1) of the proposed rule, be 
changed to agree verbatim with the procedures specified in Boeing 
Service Letter 737-SL-24-111, dated February 27, 1996. The commenter 
states that the proposed requirement implies that the protective 
methods need to be incorporated regardless of the condition of the wire 
bundles, whereas the service letter does not specify incorporation of 
wire protection features unless contact between the wiring and junction 
box is found. The commenter adds that such action would require re-
inspection of the fleet, in addition to added work that may be 
unjustified. The commenter also adds that installation of wire 
protection would not be necessary in that the affected wire bundles are 
short in length and, due to the relatively rigid nature of the 
installation at the pressure seal, if a wire bundle was found to have 
adequate clearance from the cover, this condition probably would not 
change.
    The FAA does not agree. Although there may be no damage to the 
wiring found during the inspection, the chafing condition that prompted 
this rulemaking action could still develop eventually, due to airplane 
vibration. Incorporation of the wire protection features will ensure 
that this condition

[[Page 52491]]

does not develop. No change to the final rule is necessary in this 
regard.

Add Work Hours to Cost Impact Section

    One commenter asks that the estimate of 8 work hours per airplane 
for doing the proposed actions, as specified in the Cost Impact section 
of the proposed rule, be changed. The commenter states that the 
estimate is not accurate based on the amount of operational checks 
required after disturbing the affected connectors/systems in the 
junction boxes to repair damage to wiring. The commenter recommends 
that the estimate be changed to 35 work hours per aircraft and adds 
that this labor estimate is based on its experience with accomplishment 
of the original release of the referenced service letter.
    The FAA does not agree with the commenter's request to include the 
work hours necessary for repairs of the wiring and subsequent 
operational checks in the Cost Impact section of the proposed AD. The 
Cost Impact section only includes the ``direct'' costs of the specific 
actions required, which include inspecting the wire bundles and 
protecting the wires from chafing. The AD does not include the cost of 
``on-condition'' actions, such as repair of the wiring if chafing is 
detected during the required inspection (``repair, if necessary''). 
Such on-condition repair actions would be required to be accomplished, 
regardless of AD direction, to correct an unsafe condition identified 
in an airplane and to ensure the airworthiness of that airplane, as 
required by the Federal Aviation Regulations. No change to the work 
hour estimate in the final rule is necessary.

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 change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 3,719 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 1,467 airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 8 
work hours per airplane to accomplish the required actions, and that 
the average labor rate is $60 per work hour. The cost of required parts 
will be negligible. Based on these figures, the cost impact of the AD 
on U.S. operators is estimated to be $704,160, or $480 per airplane.
    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. The cost impact figures discussed 
in AD rulemaking actions represent only the time necessary to perform 
the specific actions actually required by the AD. These figures 
typically do not include incidental costs, such as the time required to 
gain access and close up, planning time, or time necessitated by other 
administrative actions.

Regulatory Impact

    The regulations adopted herein will not have a substantial direct 
effect 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, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 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 adding the following new 
airworthiness directive:

2001-20-10  Boeing: Amendment 39-12458. Docket 2000-NM-146-AD.

    Applicability: All Model 737-100, -200, -300, -400, and -500 
series airplanes; and Model 737-600, -700, -800, and -900 series 
airplanes, line numbers 1 through 706 inclusive; 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 (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 chafing of wire bundles in four junction boxes in the 
main wheel well, which could result in arcing and consequent fire in 
the main wheel well or passenger cabin, or inability to stop the 
flow of fuel to an engine or to the auxiliary power unit in the 
event of fire, accomplish the following:

Inspection

    (a) Within 18 months after the effective date of this AD, 
perform a detailed visual inspection of the wire bundles in the four 
junction boxes formed by electrical disconnect brackets on the left 
and right sides of the main wheel wells to detect damage or chafing, 
as specified in Boeing Service Letter 737-SL-24-111-B, dated January 
16, 2001.

    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.''

    (1) If no chafing is detected, prior to further flight, protect 
the wire bundles from chafing against the cover plate of the 
junction box, according to the service letter.
    (2) If any chafing is detected, prior to further flight, repair 
the wiring in accordance with the service letter, and protect the 
wire bundles from chafing against the cover plate of the junction 
box, according to the service letter.

    Note 3: Boeing Service Letter 737-SL-24-111-B, dated January 16, 
2001, refers to Boeing Standard Wiring Practices Manual D6-54446, 
Subject 20-10-13, as the

[[Page 52492]]

appropriate source of repair instructions if any damaged wiring is 
found.

Alternative Methods of Compliance

    (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 Aircraft Certification 
Office (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 4: 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

    (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.

Incorporation by Reference

    (d) The actions shall be done in accordance with Boeing Service 
Letter 737-SL-24-111-B, including Attachment, dated January 16, 
2001. This incorporation by reference was approved by the Director 
of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR 
part 51. 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.

Effective Date

    (e) This amendment becomes effective on November 20, 2001.

    Issued in Renton, Washington, on October 4, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-25616 Filed 10-15-01; 8:45 am]
BILLING CODE 4910-13-P