[Federal Register Volume 65, Number 153 (Tuesday, August 8, 2000)]
[Rules and Regulations]
[Pages 48371-48373]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19817]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-320-AD; Amendment 39-11851; AD 2000-15-18]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100 and -200 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment supersedes an existing airworthiness directive 
(AD), applicable to certain Boeing Model 737-100 and -200 series 
airplanes, that currently requires inspections to detect cracking of 
the support fittings of the Krueger flap actuator; and, if necessary, 
replacement of existing fittings with new steel fittings and 
modification of the aft attachment of the actuator. That AD also 
provides for an optional terminating modification that constitutes 
terminating action for the repetitive inspections. This amendment 
requires accomplishment of the previously optional terminating action. 
This amendment is prompted by reports of cracking due to fatigue and 
stress corrosion of the support fittings of the Krueger flap actuator. 
The actions specified by this AD are intended to prevent such cracking, 
which could result in fracturing of the actuator attach lugs, 
separation of the actuator from the support fitting, severing of the 
hydraulic lines, and resultant loss of hydraulic fluids. These 
conditions, if not corrected, could result in possible failure of one 
or more hydraulic systems, and consequent reduced controllability of 
the airplane.

DATES: Effective September 12, 2000.
    The incorporation by reference of Boeing Service Bulletin 737-57-
1129, Revision 2, dated May 28, 1998, is approved by the Director of 
the Federal Register as of September 12, 2000.
    The incorporation by reference of Boeing Service Bulletin 737-57-
1129, Revision 1, dated October 30, 1981; as revised by Notice of 
Status Change 737-57-1129 NSC 1, dated July 23, 1982; Notice of Status 
Change 737-57-1129 NSC 2, dated April 14, 1983; and Notice of Status 
Change 737-57-1129 NSC 3, dated May 18, 1995; as listed in the 
regulations; was approved previously by the Director of the Federal 
Register as of September 17, 1996 (61 FR 41957, August 13, 1996).

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: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2028; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by superseding AD 96-17-04, 
amendment 39-9712 (61 FR 41957, August 13, 1996), which is applicable 
to certain Boeing Model 737-100 and -200 series airplanes, was 
published in the Federal Register on March 15, 2000 (65 FR 13919). The 
action proposed to continue to require inspections to detect cracking 
of the support fittings of the Krueger flap actuator on each wing; and 
to mandate replacement of any existing aluminum fitting with a new 
steel fitting and modification of the actuator aft attachment.

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.

[[Page 48372]]

Support for the Proposed Rule

    One commenter states that it has no objection to the proposed rule.

Request for Credit for Work Accomplished Previously

    One commenter requests that the proposed AD be revised to provide 
credit for accomplishment of the terminating modification per Boeing 
Service Bulletin 737-57-1129, Revision 1, dated October 30, 1981; as 
revised by Notices of Status Change 737-57-1129 NSC 1, dated July 23, 
1982; 737-57-1129 NSC 2, dated April 14, 1983; or 737-57-1129 NSC 3, 
dated May 18, 1995. The commenter states that it has previously 
accomplished the terminating modification in accordance with Revision 1 
of the service bulletin.
    The FAA concurs with the intent of the commenter's request. 
However, the FAA points out that ``Note 2'' of this AD already provides 
such credit for accomplishment of the terminating modification prior to 
the effective date of this AD in accordance with Boeing Service 
Bulletin 737-57-1129, Revision 1, as revised by Notices of Status 
Change 737-57-1129 NSC 1, 737-57-1129 NSC 2, and 737-57-1129 NSC 3. 
Therefore, no change to the final rule is necessary.

Request To Extend Use of Aluminum Support Fittings

    One commenter questions the FAA's rationale for prohibiting 
installation of new or serviceable aluminum support fittings as of the 
effective date of this AD, as provided by paragraph (c) of the proposed 
rule. The commenter states that gradually phasing out the use of 
aluminum fittings over the five-year compliance time allowed by 
paragraph (b) of the proposed AD would provide ``an equivalent level of 
safety.''
    The commenter states no justification for its request, and the FAA 
does not concur with the commenter's request. The FAA's decision to 
prohibit installation of aluminum support fittings, as required by this 
AD, is based on the unsatisfactory service history of these parts. 
Because of the criticality of the unsafe condition addressed in this 
AD, the FAA finds that it would be inappropriate to continue to allow 
replacement of existing aluminum fittings with new or serviceable 
aluminum support fittings after the effective date of this AD. In 
addition, the FAA notes that paragraph (c) of AD 96-17-04 prohibits 
installation of aluminum support fittings of four part numbers as of 
September 17, 1996 (the effective date of that AD). This AD adds four 
more part numbers of aluminum support fittings to the list of those 
that cannot be installed after the effective date of this AD. No change 
to 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 as proposed.

Cost Impact

    There are approximately 727 Model 737-100 and -200 series airplanes 
of the affected design in the worldwide fleet. The FAA estimates that 
270 airplanes of U.S. registry will be affected by this AD.
    The inspections that are currently required by AD 96-17-04 and 
retained in this AD take approximately 12 work hours per airplane (6 
work hours per wing) to accomplish, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the currently 
required inspections on U.S. operators is estimated to be $194,400, or 
$720 per airplane, per inspection.
    The replacement and modification required by this AD will take 
approximately 88 work hours per airplane (44 work hours per wing) to 
accomplish, at an average labor rate of $60 per work hour. Required 
parts will cost approximately $12,226 per airplane. Based on these 
figures, the cost impact of the replacement and modification required 
by this AD on U.S. operators is estimated to be $4,726,620, or $17,506 
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.

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 removing amendment 39-9712 (61 FR 
41957, August 13, 1996), and by adding a new airworthiness directive 
(AD), amendment 39-11851, to read as follows:

2000-15-18  Boeing: Amendment 39-11851. Docket 99-NM-320-AD. 
Supersedes AD 96-17-04, Amendment 39-9712.

    Applicability: Model 737-100 and -200 series airplanes, line 
numbers 001 through 813 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 (d) 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 possible failure of one or more hydraulic systems and 
consequent reduced controllability of the airplane, accomplish the 
following:

Restatement of Requirements of AD 96-17-04

Repetitive Inspections

    (a) Within one year after September 17, 1996 (the effective date 
of AD 96-17-04, amendment 39-9712), perform an eddy

[[Page 48373]]

current inspection to detect cracking of the support fitting of the 
Krueger flap actuator on each wing, in accordance with Boeing 
Service Bulletin 737-57-1129, Revision 1, dated October 30, 1981; as 
revised by Notices of Status Change 737-57-1129 NSC 1, dated July 
23, 1982; 737-57-1129 NSC 2, dated April 14, 1983; and 737-57-1129 
NSC 3, dated May 18, 1995; or Revision 2, dated May 28, 1998.
    (1) If no cracking is detected, repeat the inspection required 
by paragraph (a) of this AD thereafter at intervals not to exceed 
3,000 hours time-in-service.
    (2) If any cracking is detected, prior to further flight, 
accomplish the replacement and modification specified in paragraph 
(b) of this AD.

New Requirements of This AD:

Terminating Action

    (b) Within 5 years after the effective date of this AD: Replace 
any existing aluminum support fitting of the Krueger flap actuator 
on each wing with a steel fitting, and modify the actuator aft 
attachment, in accordance with Boeing Service Bulletin 737-57-1129, 
Revision 2, dated May 28, 1998. Accomplishment of this replacement 
and modification constitutes terminating action for the repetitive 
inspections required by paragraph (a) of this AD.

    Note 2: Replacement of the existing aluminum support fitting of 
the Krueger flap actuator on each wing with a steel fitting, and 
modification of the actuator aft attachment, prior to the effective 
date of this AD, in accordance with Boeing Service Bulletin 737-57-
1129, Revision 1, dated October 30, 1981; as revised by Notices of 
Status Change 737-57-1129 NSC 1, dated July 23, 1982; 737-57-1129 
NSC 2, dated April 14, 1983; and 737-57-1129 NSC 3, dated May 18, 
1995; is considered acceptable for compliance with the modification 
required by paragraph (b) of this AD.

Spares

    (c) As of the effective date of this AD, no person shall install 
on any airplane any aluminum support fitting identified in the 
``Existing Part Number'' column of Paragraph 2.D. of Boeing Service 
Bulletin 737-57-1129, Revision 2, dated May 28, 1998.

Alternative Methods of Compliance

    (d) 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 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 Permits

    (e) Special flight permits may be issued in accordance with 
Secs. 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

    (f) The actions shall be done in accordance with Boeing Service 
Bulletin 737-57-1129, Revision 1, dated October 30, 1981; as revised 
by Notice of Status Change 737-57-1129 NSC 1, dated July 23, 1982; 
Notice of Status Change 737-57-1129 NSC 2, dated April 14, 1983; and 
Notice of Status Change 737-57-1129 NSC 3, dated May 18, 1995; or 
Boeing Service Bulletin 737-57-1129, Revision 2, dated May 28, 1998; 
as applicable.
    (1) The incorporation by reference of Boeing Service Bulletin 
737-57-1129, Revision 2, dated May 28, 1998, is approved by the 
Director of the Federal Register, in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51.
    (2) The incorporation by reference of Boeing Service Bulletin 
737-57-1129, Revision 1, dated October 30, 1981; as revised by 
Notice of Status Change 737-57-1129 NSC 1, dated July 23, 1982; 
Notice of Status Change 737-57-1129 NSC 2, dated April 14, 1983; and 
Notice of Status Change 737-57-1129 NSC 3, dated May 18, 1995; was 
approved previously by the Director of the Federal Register as of 
September 17, 1996 (61 FR 41957, August 13, 1996).
    (3) 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

    (g) This amendment becomes effective on September 12, 2000.

    Issued in Renton, Washington, on July 31, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19817 Filed 8-7-00; 8:45 am]
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