[Federal Register Volume 66, Number 134 (Thursday, July 12, 2001)]
[Rules and Regulations]
[Pages 36445-36447]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-17117]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-39-AD; Amendment 39-12316; AD 2001-14-06]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-300, -400, and -500 
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 all Boeing Model 737-300, -400, and -500 series 
airplanes, that requires repetitive inspections of certain connectors 
located in the main wheel wells to detect discrepancies; and corrective 
action, if necessary. This amendment is prompted by reports indicating 
engine shutdown during flight due to uncommanded movement of the engine 
shutoff valve. These actions are necessary to detect and correct 
discrepancies of certain connectors located in the main wheel wells, 
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.

DATES: Effective August 16, 2001.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 16, 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 all Boeing Model 737-300, -400, 
and -500 series airplanes was published in the Federal Register on 
August 28, 2000 (65 FR 52049). That action proposed to require 
repetitive inspections of certain connectors located in the main wheel 
wells to detect discrepancies; and corrective action, if necessary.

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.

Supportive Comment

    One commenter states that it has done the initial inspection 
specified in the proposed rule, and is in agreement with the 
recommendation for continued repetitive inspections.

Typographical Errors

    Two commenters note that there are two typographical errors in 
Boeing Service Letter 737-SL-24-138, dated May 24, 1999; which is 
specified in the proposed rule as the service information necessary to 
do the inspections and corrective action. The first error is on page 3 
of the service letter. Action #4 identifies ``connector D51641;'' the 
correct number for the connector is D5164J. The FAA agrees that the 
identification of connector D51641 is in error and has revised 
paragraph (a) of the final rule to identify each affected connector. 
This action will eliminate any confusion as to which connectors require 
inspection, and will minimize the possibility of operators performing 
the inspections on the wrong connector.
    The second error is in the ``References,'' section on page 1 of the 
service letter and identifies ``Dt-54446, Standard Wiring Practice 
Manual, Subject 20-60-08;'' the correct reference is D6-54446. The FAA 
agrees that this is an incorrect reference and has advised the 
manufacturer accordingly. As this change is minor and not part of any 
procedures specified for doing the actions in the final rule, no change 
to the final rule is necessary in this regard.

Extend Compliance Time

    Two commenters request an extension of the compliance time for the

[[Page 36446]]

inspections specified in paragraph (a) of the proposed rule.
    One commenter asks that the compliance time for the initial 
inspection be extended from 12 months after the effective date of the 
AD, to the later of 12 months or 3,000 flight cycles after the 
effective date of the AD. The commenter also asks that the repetitive 
inspections be accomplished at the later of 18 months or 4,500 flight 
hours, instead of at intervals of 18 months. The commenter states that 
this extension is requested so it can do the inspections at a `C'-
check. The commenter adds that this would provide the opportunity for 
operators to accomplish the work at a scheduled maintenance visit, 
instead of scheduling special visits.
    The FAA does not concur to extend the compliance time for doing the 
initial inspection to the later of 12 months or 3,000 flight cycles. 
Such an extension may allow airplanes with low utilization rates to go 
without being inspected for several years. The present condition of the 
electrical connectors on each airplane is unknown, and contaminated 
electrical connectors are subject to corrosion regardless of whether or 
not the airplane is accumulating flight cycles. After doing the initial 
inspection, and, if necessary, correcting any discrepancies, the 
electrical connectors will be in a known condition for safe operation 
of the airplane. In this case, we concur that the repetitive inspection 
interval can be extended somewhat, but the interval of 4,500 flight 
hours will not provide an adequate level of safety for airplanes with 
low utilization rates, as stated above.
    Another commenter asks that the compliance time for the repetitive 
inspections be extended from 12 months to 24 months. The commenter 
states that this would allow it to accomplish the required actions 
during regularly scheduled maintenance intervals.
    We concur with the commenter and have extended the 18-month 
repetitive inspection interval specified in paragraph (a) of this final 
rule to 24 months.

Optional Terminating Action

    One commenter asks that optional terminating action be included for 
the repetitive inspections specified in paragraph (a) of the proposed 
rule. The commenter suggests two possible terminating actions, as 
follows:
     Inspect the connectors in accordance with the service 
letter and replace the spare pins and filler plugs with pins that have 
spare wires installed. (This action would provide the same level of 
sealing capability as the existing wires terminated within the 
connector.) Or
     Replace the existing connectors with new connectors having 
no spare pin positions. (This action would completely remove any 
potential of contaminants entering through a spare pin location.)
    The FAA does not concur. Missing filler rods or spare contacts 
could not be verified in two of the three incidents that were reported 
to us. As a result, we have not been able to determine the path of the 
contamination that entered the connectors. It is possible that 
contaminants could enter the connectors despite the presence of filler 
rods and contacts with wires. Without verification of the cause of the 
path of contamination, repetitive inspections are required to ensure 
that electrical arcing and uncommanded closure of the engine fuel shut-
off valves do not occur. Termination of the repetitive inspections will 
necessitate design changes that will decrease the effects of connector 
contamination. Should the manufacturer develop such design changes, we 
may consider additional rulemaking in the future. No change to the 
final rule is necessary in this regard.

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 previously 
described. 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 1,974 Model 737 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 755 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 1 work hour per airplane to accomplish the required 
inspection, 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 inspection required by this 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 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:

2001-14-06 Boeing: Amendment 39-12316. 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

[[Page 36447]]

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 
located in the main wheel wells, 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 D5162P, D5162J, 
D5164P, and D5164J (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 24 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.

Incorporation by Reference

    (d) The actions shall be done in accordance with Boeing Service 
Letter 737-SL-24-138, including attachment, dated May 24, 1999. 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 August 16, 2001.

    Issued in Renton, Washington, on July 2, 2001.
Vi L. Lipski,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-17117 Filed 7-11-01; 8:45 am]
BILLING CODE 4910-13-U