[Federal Register Volume 67, Number 52 (Monday, March 18, 2002)]
[Rules and Regulations]
[Pages 11891-11893]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-6201]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-21-AD; Amendment 39-12675; AD 2002-05-07]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
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 certain Boeing Model 737-100, -200, -200C, -300, -400, 
and -500 series airplanes. For certain airplanes, this action requires 
repetitive inspections for discrepancies of the rear spar attachments 
and cracks in the upper flange of the inboard track at the rear spar 
attachment of each outboard flap, and eventual rework of the flap track 
assembly and rear spar attachments, including replacement of the flap 
track with a new track, if necessary. For all airplanes, this action 
requires repetitive inspections for cracks in the upper flange of the 
inboard flap tracks at the rear spar attachments, and corrective 
action, if necessary. The actions specified by this AD are intended to 
find and fix discrepancies of the inboard tracks of the outboard flaps, 
which could result in loss of the outboard trailing edge flaps and 
consequent reduced controllability of the airplane. These actions are 
intended to address the identified unsafe condition.

DATES: Effective April 22, 2002.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 22, 2002.

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: James Blilie, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2131; 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 Boeing Model 737-100, -200, -200C, 
-300, -400, and -500 series airplanes was published as a supplemental 
notice of proposed rulemaking (NPRM) in the Federal Register on August 
2, 2001 (66 FR 40162). That action proposed to expand the applicability 
and remove the optional terminating action of the proposed AD. For 
certain airplanes, that action proposed to require new repetitive 
inspections for discrepancies of the rear spar attachments and cracks 
in the upper flange of the inboard track at the rear spar attachment of 
each outboard flap, and eventual rework of the flap track assembly and 
rear spar attachments, including replacement of the flap track with a 
new track, if necessary. For all airplanes, that action proposed to 
require repetitive inspections for cracks in the upper flange of the 
inboard flap tracks at the rear spar attachments, 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.

Request to Clarify Compliance Time

    Several commenters note that in paragraphs (a) and (c)(1) of the 
Supplemental NPRM, the phrase ``whichever occurs later,'' is used when 
only one compliance time is given. They ask that the compliance time be 
clarified.
    The FAA concurs that clarification is required and, accordingly, 
has deleted the phrase ``whichever occurs later'' from paragraphs (a) 
and (c)(1) of this final rule.

Request to Clarify Which Airplanes Are Subject to Paragraph (a) of 
the Supplemental NPRM

    One commenter points out that paragraph (a) of the Supplemental 
NPRM is applicable to all Model 737 series airplanes with line numbers 
1 through 1585, whereas the service bulletin cited is effective only 
for the Model 737-100, -200, and -200C series airplanes. The commenter 
requests clarification as to the applicability of paragraph (a) of the 
AD.
    The FAA concurs that clarification is necessary. Our intent was to 
have paragraph (a) of this AD apply only to the Model 737-100, -200, 
and -200C series airplanes. Accordingly, we have inserted the phrase 
``[for] Model 737-100, -200, and -200C series [airplanes]'' in 
paragraph (a) of this final rule to specify the correct applicability.
    Another commenter suggests that the part of paragraph (a) of the 
Supplemental NPRM which reads ``* * * and airplanes with [line numbers] 
L/N 870 through 1585 on which the original flap tracks have been 
replaced with certain tracks as specified in Boeing Service Bulletin 
737-57A1249, Revision 1 * * *'' could be interpreted in two different 
ways. The commenter requests clarification.
    The FAA agrees that the sentence could be misunderstood and, 
accordingly, has revised the language in paragraph (a) of this final 
rule to read

[[Page 11892]]

``* * * and those airplanes with L/Ns 870 through 1585 inclusive, which 
either still have their original flap tracks or which have had the 
original flap tracks replaced with certain tracks as specified in 
Boeing Service Bulletin 737-57A1249, Revision 1 * * *''

Request to Clarify Which Flap Tracks Are Affected

    One commenter states that the Supplemental NPRM does not specify 
which flap tracks are affected by paragraph (a) of the AD. The 
commenter requests that specific part numbers and dash numbers be 
listed in the final rule.
    The FAA does not concur. The intent of paragraph (a) of this AD is 
to include all flap tracks for Model 737-100, -200, and -200C series 
airplanes with L/Ns 1 through 1585, except for certain flap tracks 
which are specifically excluded in the effectivity of the service 
bulletin. Accordingly, no change has been made to the final rule in 
this regard.

Request to Correct Reference to Part of Accomplishment Instructions

    One commenter indicates that paragraph (d) of the Supplemental 
NPRM, which requires repetitive inspections for cracking in the upper 
flange of the inboard track of each outboard flap at the rear spar 
attachments, should refer to Part I of the Accomplishment Instructions 
rather than Part II of those instructions.
    The FAA concurs. The original reference in the Supplemental NPRM to 
Part II was an error. The language in paragraph (d) of this final rule 
has been changed accordingly.

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 2,890 Boeing Model 737-100, -200, -200C, -
300, -400, and -500 series airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 1,100 airplanes of U.S. 
registry will be affected by this AD.
    It will take approximately 4 work hours per airplane to accomplish 
the required inspections at an average labor rate of $60 per work hour. 
Based on these figures, the cost impact of the required inspections on 
U.S. operators is estimated to be $264,000, or $240 per airplane.
    It will take approximately 12 work hours per airplane to accomplish 
the required rework at an average labor rate of $60 per work hour. 
Required parts will cost approximately $532. Based on these figures, 
the cost impact of the required rework on U.S. operators is estimated 
to be $1,377,200, or $1,252 per airplane.
    The cost impact figures discussed above are 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:

2002-05-07  Boeing: Amendment 39-12675. Docket 99-NM-21-AD.

    Applicability: Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes; certificated in any category; EXCEPT airplanes on 
which any replacement flap tracks were installed according to Boeing 
Service Bulletin 737-57-1203, dated November 15, 1990, or production 
equivalent.

    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 (f) 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.

    Note 2: Airplanes modified according to Boeing Service Bulletin 
737-57-1065 are subject to additional work as described in this AD 
and in Boeing Service Bulletin 737-57A1249, Revision 1, dated June 
1, 2000.

    To find and fix discrepancies of the inboard tracks of the 
outboard flaps, which could result in loss of the outboard trailing 
edge flaps and consequent reduced controllability of the airplane, 
accomplish the following:

Initial Inspections

    (a) For Model 737-100, -200, and -200C series airplanes with 
line numbers (L/N) 1 through 869 inclusive, and those airplanes with 
L/Ns 870 through 1585 inclusive, which either still have their 
original flap tracks or which have had the original flap tracks 
replaced with certain tracks as specified in Boeing Service Bulletin 
737-57A1249, Revision 1, including Appendix A, dated June 1, 2000: 
Within 6 months after the effective date of this AD, accomplish the 
requirements of paragraphs (a)(1) and (a)(2) of this AD, according 
to Boeing Service Bulletin 737-57A1249, Revision 1, including 
Appendix A, dated June 1, 2000.
    (1) Perform a detailed visual inspection for discrepancies 
(e.g., corrosion, or missing, damaged, or migrated anti-fret strips 
and tapered shims) of the rear spar attachments of the flap tracks.

[[Page 11893]]

    (2) Perform detailed visual, high frequency eddy current (HFEC), 
and ultrasonic inspections for cracking in the upper flange of the 
inboard track of each outboard flap at the rear spar attachments.

    Note 3: Inspections and rework accomplished according to Boeing 
Alert Service Bulletin 737-57A1249, including Appendix A, dated 
December 16, 1999, is considered acceptable for compliance with the 
applicable action specified in this AD.


    Note 4: 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.''

Repetitive Inspections

    (b) For airplanes subject to paragraph (a) of this AD: If no 
discrepancy is found during any inspection required by paragraph (a) 
of this AD, thereafter, repeat the inspections specified in 
paragraph (a) of this AD at intervals not to exceed 9 months, until 
the actions required by paragraph (c) of this AD have been 
accomplished.

Rework

    (c) For airplanes subject to paragraph (a) of this AD: At the 
applicable time specified in paragraph (c)(1) or (c)(2) of this AD, 
accomplish rework of the flap track assembly and aft flap track 
attachments (including removal of the flap track; a detailed visual 
inspection for a missing, damaged, or migrated anti-fret strip and 
tapered shim of the rear spar attachments of the flap track; 
replacement of the anti-fret strip with a new aluminum anti-fret 
strip (or installation of an aluminum strip if no strip is 
installed), as applicable; replacement of the tapered shim with a 
new shim (or installation of a shim if no shim is installed); eddy 
current and ultrasonic inspections for fatigue cracking of the flap 
tracks; a detailed visual inspection for corrosion of the flap 
tracks; and rework of attachment holes), including replacement of 
the flap tracks, as applicable, by accomplishing all actions 
specified in Part II of the Accomplishment Instructions of Boeing 
Service Bulletin 737-57A1249, Revision 1, including Appendix A, 
dated June 1, 2000. Do these actions according to that service 
bulletin, except as provided by paragraph (e) of this AD. 
Accomplishment of the actions required by this paragraph constitutes 
terminating action for the repetitive inspections required by 
paragraph (b) of this AD.
    (1) If no discrepancy is found during any inspection required by 
paragraph (a) or (b) of this AD: Do the rework within 24 months 
after the effective date of this AD.
    (2) If any discrepancy is found during any inspection required 
by paragraph (a) or (b) of this AD: Do the rework prior to further 
flight.

Repetitive Inspections

    (d) For all airplanes: At the applicable time specified in 
paragraph (d)(1) or (d)(2) of this AD, and thereafter at least every 
24 months, perform detailed visual, HFEC, and ultrasonic inspections 
for cracking in the upper flange of the inboard track of each 
outboard flap at the rear spar attachments according to Part I of 
the Accomplishment Instructions of Boeing Service Bulletin 737-
57A1249, Revision 1, including Appendix A, dated June 1, 2000.
    (1) For airplanes subject to paragraph (c) of this AD, do the 
inspections within 10 years after accomplishment of the rework 
according to paragraph (c) of this AD.
    (2) For airplanes other than those identified in paragraph 
(d)(1) of this AD, do the inspections within 10 years since the 
airplane's date of manufacture, or within 6 months after the 
effective date of this AD, whichever occurs later.

Repair Instructions and Exception to Procedures in Service Information

    (e) If any discrepancy is found during any action required by 
paragraphs (a), (b), or (c) of this AD, and the service bulletin 
specifies to contact Boeing for appropriate action; OR if any 
discrepancy is found during inspections according to paragraph (d) 
of this AD: Prior to further flight, repair according to a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA; or according to data meeting the type certification 
basis of the airplane approved by a Boeing Company Designated 
Engineering Representative (DER) who has been authorized by the 
Manager, Seattle ACO, to make such findings. For a repair method to 
be approved by the Manager, Seattle ACO, as required by this 
paragraph, the approval letter must specifically reference this AD.

Alternative Methods of Compliance

    (f) 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 ACO. 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 5: 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

    (g) 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

    (h) Except as provided by paragraph (e) of this AD, the actions 
shall be done in accordance with Boeing Service Bulletin 737-
57A1249, Revision 1, including Appendix A, dated June 1, 2000. 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

    (i) This amendment becomes effective on April 22, 2002.

    Issued in Renton, Washington, on March 8, 2002.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-6201 Filed 3-15-02; 8:45 am]
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