AIRWORTHINESS DIRECTIVE

CAA-AD-082/2001

Date of issue: September 07, 2001

AIRCRAFT - FLOOR BEAMS AND TRANSVERSE BEAMS - INSPECTION/MODIFICATION

Applicability: Model 737-100, -200, and -200C series airplanes; as listed in Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992; certificated in any category.

Effective date: November 01, 2001

Compliance: Required as indicated in FAA AD 2001-17-18.

Remarks: The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel: 420 2 33320922, fax: 420 2 20562270.

Ing. Pavel MATOUŠEK

Director of Airworthiness Division

CAA CZ

2001-17-18 Boeing: Amendment 39-12409. Docket 99-NM-310-AD.

Applicability: Model 737-100, -200, and -200C series airplanes; as listed in Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992; 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)(1) 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 cracks in the floor beams at the aileron control quadrant cutout and in the floor beams and pressure web transverse beams above the main wheel well, which could result in rapid loss of cabin pressure and reduced structural integrity of the airplane, accomplish the following:

Initial Inspection and Follow-On Actions: Groups 1, 2, and 5

(a) For airplanes in Groups 1, 2, and 5; as listed in Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992: Prior to the accumulation of 12,000 total flight cycles, within 6,000 flight cycles after the effective date of this AD, or within 15 months after the effective date of this AD, whichever occurs latest, perform a detailed visual inspection to detect cracking of the left and right buttock line (LBL and RBL) 24.8 floor beams in the area of the aileron control quadrant cutout, in accordance with Part II of the Accomplishment Instructions of the service bulletin.

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 appropriated by the inspector. Inspection aids such as mirror, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required

(1) If no cracking is detected, repeat the inspection thereafter at intervals not to exceed 6,000 flight cycles, until the modification in paragraph (c)(1) of this AD is done.

(2) If cracking is detected that is within the limits specified in Part II, Paragraphs C.1. and C.2., of the Accomplishment Instructions of the service bulletin, prior to further flight, repair the crack per the service bulletin, and accomplish the modification specified in paragraph (c)(1) of this AD.

(3) If cracking is detected that is outside the limits identified in Part II, Paragraphs C.1. and C.2., of the Accomplishment Instructions of the service bulletin, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with a method approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For the repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.

Initial Inspection and Follow-On Actions: Groups 1, 2, 3, and 4

(b) For airplanes in Groups 1, 2, 3, and 4; as listed in Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992: Prior to the accumulation of 20,000 total flight cycles, within 6,000 flight cycles after the effective date of this AD, or within 15 months after the effective date of this AD, whichever occurs latest, perform a detailed visual inspection to detect cracking of the transverse beams and floor beams at the beam intersections in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(1) If no cracking is detected, repeat the inspection thereafter at intervals not to exceed 6,000 flight cycles, until the modification in paragraph (c)(2) of this AD is done.

(2) If any cracking is detected, prior to further flight, repair in accordance with a method approved by the Manager, Seattle ACO, or in accordance with a method approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings. For the repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.

Modifications (Terminating Action)

(c) The following modifications in accordance with Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992, constitute terminating action for certain requirements of this AD.

(1) For airplanes in Groups 1, 2, and 5; as listed in the service bulletin: Modification of the LBL and RBL 24.8 floor beams in the area of the aileron control quadrant cutout in accordance with Part I of the Accomplishment Instructions of the service bulletin constitutes terminating action for the initial and repetitive inspection requirements of paragraph (a) of this AD.

(2) For airplanes in Groups 1, 2, 3, and 4; as listed in the service bulletin: Modification of the transverse beams and floor beams at the beam intersections in accordance with Part III or Part I, as applicable, of the Accomplishment Instructions of the service bulletin constitutes terminating action for the repetitive inspections required by paragraph (b) of this AD.

Note 3: The modifications specified in Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992, are required by AD 90-06-02, amendment 39-6489, and AD 93-17-08, amendment 39-8679.

Alternative Methods of Compliance

(d) (1) 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.

(2) Repairs approved previously as alternative methods of compliance in accordance with AD 90-06-02, amendment 39-6489, and AD 93-17-08, amendment 39-8679, are approved as alternative methods of compliance with this AD for the AREA OF REPAIR ONLY.

Note 4: 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 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

(f) Except as provided in paragraphs (a)(3) and (b)(2) of this AD, the actions shall be done in accordance with Boeing Service Bulletin 737-57-1139, Revision 4, dated April 16, 1992. 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

(g) This amendment becomes effective on October 1, 2001.

Issued in Renton, Washington, on August 17, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 01-21393 Filed 8-24-01; 8:45 am]

BILLING CODE 4910-13-U