[Federal Register Volume 65, Number 167 (Monday, August 28, 2000)]
[Proposed Rules]
[Pages 52049-52051]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-21872]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-39-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -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 all Boeing Model 737-300, -400, 
and -500 series airplanes.
    This proposal would require repetitive inspections of certain 
connectors located in the main wheel wells to detect discrepancies; and 
corrective action, if necessary. This action is necessary to detect and 
correct such discrepancies, which could result in electrical arcing of 
the connectors, uncommanded closure of the engine fuel shut-off valves, 
and consequent in-flight loss of thrust or engine shutdown from lack of 
fuel. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by October 12, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-39-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: 
9-

[[Page 52050]]

[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-39-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, 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-39-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-39-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating engine shutdown during 
flight due to uncommanded movement of the engine shutoff valve on three 
Model 737 series airplanes. Investigation revealed that connectors 
located in certain disconnect panels had burned and were damaged, and 
the printed circuit cards located in the fuel system module were also 
damaged. Examination of connectors and cards returned to the 
manufacturer indicated that a short occurred between the contacts for 
the outboard landing lights and the contacts for the fuel shut-off 
valve mounted on the wing rear spar. In one incident the spare contacts 
and filler rods normally installed in the unused cavities of the 
connectors were not installed, creating a path for contamination to 
enter the connectors through the open, unused cavities. However, the 
absence of spare contacts and filler rods cannot be verified as the 
single cause of the contamination. Therefore, the FAA has determined 
that the contamination also could occur when the connectors are 
properly fitted with spare contacts and filler rods. Such conditions, 
if not detected and corrected, could result in electrical arcing of the 
connectors, uncommanded closure of the engine fuel shut-off valves, and 
consequent in-flight loss of thrust or engine shutdown from lack of 
fuel.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Letter 737-SL-24-
138, dated May 24, 1999, which describes procedures for inspections of 
certain connectors (connectors are linked to the fuel shut-off valves 
and outboard landing lights) located in the main wheel wells, to detect 
discrepancies including missing spare contacts and filler rods, 
improper plugs or filler rods, or contamination or corrosion of the 
connectors. If any discrepancies are found, the service letter 
references Boeing Standard Wiring Practices Manual D6-54446, Subject 
20-60-01, for cleaning corroded or contaminated wiring; Subject 20-61-
11, for installing spare contacts in the connectors; and Subject 20-60-
08, for installing filler rods in the connectors.

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.

Differences Between Service Letter and This Proposed AD

    Operators should note that, although the service letter does not 
specify the type of inspection of the connectors to detect 
contamination or missing spare contacts and filler rods, this proposed 
AD would require a detailed visual inspection for accomplishment of the 
actions. A note has been included in this proposed rule to define that 
inspection.
    Operators also should note that this proposed AD would require the 
detailed visual inspection be accomplished within 12 months after the 
effective date of the AD, and repeated at 18-month intervals 
thereafter. The service letter identifies a one-time inspection at 
``the next convenient maintenance opportunity.'' 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 inspection (approximately 1 hour). In light of 
all of these factors, the FAA finds a 12-month compliance time for the 
initial inspection, and an 18-month repetitive inspection interval, to 
be warranted, in that those times represent appropriate intervals for 
affected airplanes to continue to operate without compromising safety.
    While Boeing Service Letter 737-SL-24-138 limits its effectivity to 
Model 737-300, -400, and -500 series airplanes having line numbers 
prior to 3095, this proposed AD would be applicable to all Model 737-
300, -400, and -500 series airplanes. In light of the fact that the 
exact cause of the contamination entering the connectors for the engine 
fuel shut-off valves mounted on the wing rear spar and for the outboard 
landing lights is as yet undetermined, and may be caused by spare 
contacts and filler rods that fall out or leak during service or by 
connectors that are properly fitted with

[[Page 52051]]

spare contacts and filler rods, the FAA has determined that all 
airplanes, as stated above, must accomplish the requirements of this 
proposed AD.

Cost Impact

    There are approximately 1,974 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 755 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 1 work hour per airplane to accomplish the 
proposed inspection, 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 $45,300, or $60 per airplane, per inspection cycle.
    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 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-39-AD.

    Applicability: All Model 737-300, -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 (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 detect and correct discrepancies of certain connectors, which 
could result in electrical arcing of the connectors, uncommanded 
movement of the engine fuel shut-off valves to the closed position, 
and consequent in-flight loss of thrust or engine shutdown from lack 
of fuel, accomplish the following:

Repetitive Inspections/Corrective Action

    (a) Within 12 months after the effective date of this AD: 
Perform a detailed visual inspection of connectors (connectors are 
linked to the fuel shut-off valves and outboard landing lights) 
located in the main wheel wells, to detect discrepancies (missing 
spare contacts and filler rods, improper plugs or filler rods, or 
contamination or corrosion), as specified in Boeing Service Letter 
737-SL-24-138, dated May 24, 1999. Repair any discrepancies in 
accordance with the service letter, and repeat the inspection 
thereafter at intervals not to exceed 18 months.

    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.''

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 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 Permit

    (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 August 22, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-21872 Filed 8-25-00; 8:45 am]
BILLING CODE 4910-13-P