[Federal Register Volume 65, Number 124 (Tuesday, June 27, 2000)]
[Proposed Rules]
[Pages 39574-39576]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-16237]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-146-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, 
and -500 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 certain Boeing Model 737-100, -
200, -300, -400, and -500 series airplanes. This proposal would require 
inspection of wire bundles in two junction boxes in the main wheel well 
to detect chafing or damage, and follow-on actions. This action is 
necessary to prevent wire damage, 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 a fire. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by August 11, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-146-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. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments

[[Page 39575]]

sent via fax or the Internet must contain ``Docket No. 2000-NM-146-AD'' 
in the subject line and need not be submitted in triplicate. Comments 
sent via the Internet as attached electronic files must be formatted in 
Microsoft Word 97 for Windows or ASCII text.
    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 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.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 2000-NM-146-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. 2000-NM-146-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that damaged electrical 
wiring has been found in a junction box formed by electrical disconnect 
brackets on the right side of the main wheel well on certain Boeing 
Model 737 series airplanes. Several airplane systems--including the 
autopilot, the fuel shutoff valve for the right engine, and the fuel 
shutoff valve for the auxiliary power unit (APU)--failed as a result of 
the damaged wiring. The damaged wiring has been attributed to wire 
bundles chafing against the inside surface of the cover of the junction 
box. A similar junction box is located on the left side of the main 
wheel well. Damaged wiring in these junction boxes, if not corrected, 
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 APU in the event of a fire.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Letter 737-SL-24-
111, dated February 27, 1996, which describes procedures for a one-time 
inspection to detect chafing or damage of wire bundles in two junction 
boxes in the main wheel well. The subject junction boxes are located on 
the left and right sides of the main wheel well, between body stations 
716 and 727 at water line 202, where the wire bundles pass through the 
pressure seals to connectors on the disconnect brackets. The service 
letter also describes procedures for protecting the wiring from future 
damage by tying or supporting the wire bundles to prevent them from 
chafing against the cover plate of the junction box during airplane 
operations, or wrapping the wire bundles in Teflon tape or Teflon 
sleeving and lacing tape. The service letter references Boeing Standard 
Wiring Practices Manual D6-54446, Subjects 20-10-13 and 20-00-11, as 
the appropriate sources of repair instructions if any damaged wiring is 
found. Accomplishment of the actions specified in the service letter 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 letter described previously, except as discussed below.

Difference Between Service Letter and This Proposed AD

    Operators should note that, while the service letter does not 
specify the type of inspection of the wire bundles to detect chafing, 
this proposed AD would require a detailed visual inspection to detect 
chafing of the wire bundles. A note has been included in this proposed 
rule to define that inspection.
    Operators also should note that this proposed AD would require the 
inspection be accomplished within 12 months after the effective date of 
the AD. The service letter does not specify a compliance time for the 
described actions. In developing an appropriate compliance time for 
this proposed AD, the FAA considered 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 actions 
(approximately 4 hours). In light of all of these factors, the FAA 
finds a 12-month compliance time for initiating the required actions to 
be warranted, in that it represents an appropriate interval of time 
allowable for affected airplanes to continue to operate without 
compromising safety.

Cost Impact

    There are approximately 2,462 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 971 airplanes of U.S. 
registry would be affected by this proposed AD, that it would take 
approximately 4 work hours per airplane to accomplish the proposed 
actions, and that the average labor rate is $60 per work hour. The cost 
of required parts would be negligible. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$233,040, or $240 per airplane.
    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 proposed AD were not adopted. The cost impact 
figures discussed in AD

[[Page 39576]]

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 proposed herein would 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 proposal would not have federalism implications 
under Executive Order 13132.
    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 2000-NM-146-AD.
    Applicability: Model 737-100, -200, -300, -400, and -500 series 
airplanes; line numbers 1 through 2707 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 two 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 12 months after the effective date of this AD, 
perform a detailed visual inspection of the wire bundles in the 
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, dated February 
27, 1996.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: 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, in accordance with Method 1, Method 2, or Method 3, as 
specified in 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, in accordance with Method 1, Method 2, or Method 3, as 
specified in the service letter.

    Note 3: Boeing Service Letter 737-SL-24-111 references Boeing 
Standard

    Wiring Practices Manual D6-54446, Subjects 20-10-13 and 20-00-11, 
as the appropriate sources 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, 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 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.

    Issued in Renton, Washington, on June 21, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-16237 Filed 6-26-00; 8:45 am]
BILLING CODE 4910-13-P