Document ID: FAA-2007-0228-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 737-200 Series Airplanes
Posted Date: 2007-11-26T05:00Z

[Federal Register: November 26, 2007 (Volume 72, Number 226)]
[Proposed Rules]               
[Page 65909-65911]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26no07-9]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0228; Directorate Identifier 2007-NM-107-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-200 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-200 series airplanes. This proposed AD 
would require repetitive inspections to detect cracking of the support 
fittings of the Krueger flap actuators, and corrective actions if 
necessary. This proposed AD also would require eventual replacement of 
any existing aluminum support fitting on each wing with a steel 
fitting, and modification of the aft attachment of the actuator. Doing 
these actions would terminate the repetitive inspection requirements. 
This proposed AD results from reports of cracking due to fatigue and 
stress corrosion of the support fittings of the Krueger flap actuator. 
We are proposing this AD to prevent cracking of the support fittings, 
which could result in fracturing of the actuator attach lugs, 
separation of the actuator from the support fitting, severing of the 
hydraulic lines, resultant loss of hydraulic fluids, and consequent 
reduced controllability of the airplane.

DATES: We must receive comments on this proposed AD by January 10, 
2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov.
 Follow the instructions for submitting comments.

     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov
; or in person at the Docket Management Facility 

between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Nancy Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
917-6440; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2007-0228; 
Directorate Identifier 2007-NM-107-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov
, including any personal information you provide. We 

will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received reports of cracks in the support fitting of the 
Krueger flap actuator mounted on the front spar of eight affected 
airplanes. On one airplane, the lugs on the No. 1 Krueger flap actuator 
support fitting severed completely, the actuator separated from the 
front spar, and the hydraulic lines were severed. On another airplane, 
both actuator attach lugs of a No. 1 flap support fitting were also 
completely severed. The cracking is attributed to fatigue and stress 
corrosion, and it is suspected that high clamp-up stresses may be 
contributing to cracks in the actuator attach lugs. Cracking of the 
support fittings, if not corrected, could result in fracturing of the 
actuator attach lugs, separation of the actuator from the support 
fitting, severing of the hydraulic lines, resultant loss of hydraulic 
fluids, and consequent reduced controllability of the airplane.

Other Relevant Rulemaking

    On July 31, 2000, we issued AD 2000-15-18, amendment 39-11851 (65 
FR 48371, August 8, 2000). That AD applies to certain Boeing Model 737-
100 and -200 series airplanes, line numbers 001 through 813 inclusive. 
That AD 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 requires eventual replacement 
of any existing aluminum Krueger flap actuator support fitting on each 
wing with a steel fitting, which terminates the repetitive inspection 
requirements. That AD resulted from reports of cracking due to fatigue 
and stress corrosion of the support fittings of the Krueger flap 
actuator. The actions in that 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

[[Page 65910]]

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.
    Since we issued AD 2000-15-18, we have determined that the same 
unsafe condition addressed in that AD exists on certain additional 
Model 737-200 series airplanes. We were advised that Model 737-200 
series airplanes, line numbers 814 through 826 inclusive, are also 
subject to the same unsafe condition addressed in AD 2000-15-18.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-57-
1129, Revision 3, dated March 19, 2007. The service bulletin describes 
procedures for repetitive high frequency eddy current (HFEC) 
inspections to detect cracking of the support fittings of the Krueger 
flap actuators, and corrective actions if necessary. The corrective 
actions are replacement of existing fittings with new steel fittings 
and modification of the aft attachment of the actuator. This 
replacement and modification eliminates the need for the repetitive 
inspection requirements. Accomplishing the actions specified in the 
service information is intended to adequately address the unsafe 
condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously.

Costs of Compliance

    There are about 13 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                 Number of U.S.-
                Action                   Work hours     Average labor       Parts          Cost per airplane       registered           Fleet cost
                                                        rate per hour                                               airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection...........................               5             $80              $0  $400, per inspection                   3  $1,200, per inspection
                                                                                        cycle.                                    cycle.
Replacement..........................              88             $80         $29,642  $36,682.................               3  $110,046.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0228; Directorate Identifier 2007-NM-
107-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by January 
10, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-200 series airplanes, 
line numbers 814 through 826 inclusive, certificated in any 
category.

Unsafe Condition

    (d) This AD results from reports of cracking due to fatigue and 
stress corrosion of the support fittings of the Krueger flap 
actuator. We are issuing this AD to prevent cracking of the support 
fittings, which could result in fracturing of the actuator attach 
lugs, separation of the actuator from the support fitting, severing 
of the hydraulic lines, resultant loss of hydraulic fluids, and 
consequent reduced controllability of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Repetitive Inspections

    (f) Within 12 months after the effective date of this AD, do a 
high frequency eddy current (HFEC) inspection to detect cracking of 
the support fittings of the Krueger flap actuator on each wing, in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-57-1129, Revision 3, dated March 19, 
2007.

[[Page 65911]]

    (1) If no cracking is detected, repeat the inspection thereafter 
at intervals not to exceed 3,000 flight hours until the terminating 
action required by paragraph (g) of this AD is accomplished.
    (2) If any cracking is detected, before further flight, do the 
replacement and modification specified in paragraph (g) of this AD.

Terminating Action

    (g) Within 60 months after the effective date of this AD: 
Replace any existing Krueger flap actuator aluminum support fitting 
on each wing with a steel fitting, and modify the actuator aft 
attachment, in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 737-57-1129, Revision 3, 
dated March 19, 2007. Doing this replacement and modification 
terminates the repetitive inspection requirements of paragraph (f) 
of this AD.

Parts Replacement

    (h) As of the effective date of this AD, no person may install 
on any airplane any aluminum support fitting (actuator support 
assembly) identified in the ``Existing Part Number'' column of 
paragraph 2.C. of Boeing Special Attention Service Bulletin 737-57-
1129, Revision 3, dated March 19, 2007.

Actions Accomplished in Accordance With Previous Revisions of Service 
Bulletin

    (i) Actions done before the effective date of this AD in 
accordance with the service bulletins listed in Table 1 of this AD, 
are acceptable for compliance with the corresponding requirements of 
this AD.

                                Table 1.--Previous Revisions of Service Bulletins
----------------------------------------------------------------------------------------------------------------
        Boeing service bulletin                    Revision level                            Date
----------------------------------------------------------------------------------------------------------------
737-57-1129...........................  1..................................  October 30, 1981.
737-57-1129...........................  2..................................  May 28, 1998.
----------------------------------------------------------------------------------------------------------------

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.

    Issued in Renton, Washington, on November 13, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-22926 Filed 11-23-07; 8:45 am]

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