AD 99-19-27 Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes

Models named: 737-100, -200, -300, -400, -500 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 737-100, -200, -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 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 (e) 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.

Required as indicated, unless accomplished previously. To prevent failure of multiple tie bolts of main landing gear (MLG) wheel assemblies, which could result in failure of the wheel rim, rapid release of tire pressure, and possible consequent damage to the airplane and injury to passengers and flightcrew, accomplish the following: (a) Within 60 days after the effective date of this AD, perform an inspection of the MLG wheel assemblies or perform other verifications (such as a records review) to determine the part number (P/N) of each assembly. If no wheel assembly manufactured by BFGoodrich Aerospace and having P/N 3-1398-1, 3-1439-2, or 3-1439-3 is installed on the airplane, no further action is required by this AD. (b) Except as provided by paragraph (d) of this AD, if any MLG wheel assembly manufactured by BFGoodrich Aerospace and having P/N 3-1398-1, 3-1439-2, or 3-1439-3 is installed on the airplane, within 60 days after the effective date of this AD, accomplish the actions specified by paragraph (b)(1) or (b)(2) of this AD. (1) Accomplish the actions specified by (b)(1)(i) or (b)(1)(ii) of this AD. (i) Replace all tie bolts, nuts, and washers of the MLG wheel assembly with parts having the same P/N's, in accordance with the BFGoodrich component maintenance manual. Thereafter, repeat the replacement of tie bolts, nuts, and washers, at intervals not to exceed 5 tire changes, until the actions specified by paragraph (b)(2) or paragraph (c) of this AD have been accomplished. Or (ii) Perform a detailed visual inspection to detect fractures of any of the 16 tie bolts on each MLG wheel assembly, in accordance with the Boeing 737 airplane maintenance manual. Thereafter, repeat the inspection at intervals not to exceed 100 flight cycles until the actions specified by paragraph (b)(2) or paragraph (c) of this AD have been accomplished. If any fracture of any tie bolt is found during any inspection performed in accordance with this requirement, prior to further flight, replace the tie bolt, nut, and washer, in accordance with the BFGoodrich component maintenance manual, with new parts having the same P/N's. 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.'' (2) Revise the FAA-approved maintenance program as specified in paragraph (b)(2)(i) or (b)(2)(ii) of this AD. (i) Revise the FAA-approved maintenance program to require replacement of all tie bolts, nuts, and washers of the MLG wheel assembly with parts having the same P/N's, in accordance with the BFGoodrich component maintenance manual, at intervals not to exceed 5 tire changes. Or (ii) Revise the FAA-approved maintenance program to require a detailed visual inspection to detect fractures of any of the 16 tie bolts on each MLG wheel assembly, in accordance with the Boeing 737 airplane maintenance manual, at intervals not to exceed 100 flight cycles. If any fracture of any tie bolt is found during any inspection performed in accordance with this requirement, prior to further flight, replace the tie bolt, nut, and washer, in accordance with the BFGoodrich component maintenance manual, with new parts having the same P/N's. Note 3: After the maintenance program has been revised to include the procedures specified in paragraph (b)(2)(i) or (b)(2)(ii) of this AD, operators are not required to subsequently record AD compliance each time the replacement or inspection is performed. (c) If any MLG wheel assembly manufactured by BFGoodrich Aerospace and having P/N 3-1398-1, 3-1439-2, or 3-1439-3 is installed on the airplane: Except as provided by paragraph (d) of this AD, within 2 years after the effective date of this AD, modify any BFGoodrich Aerospace wheel assembly, having P/N 3-1398-1, 3- 1439-2, or 3-1439-3; by replacing all existing tie bolts, nuts, and washers, with new, improved parts; and by converting the P/N of the MLG wheel assembly to 3-1398-2 (for BFGoodrich wheel assemblies having the old P/N 3-1398-1), 3-1439-5 (for BFGoodrich wheel assemblies having the old P/N 3-1439-2), or 3-1439-6 (for BFGoodrich wheel assemblies having the old P/N 3-1439-3), as applicable; in accordance with BFGoodrich Aerospace Service Bulletin 3-1439-32-13, or BFGoodrich Aerospace Service Bulletin 3-1398-32-16, both dated August 20, 1993, as applicable. Such modification constitutes terminating action for the requirements of this AD, and the FAA- approved maintenance program procedures specified by paragraph (b)(2) of this AD may be removed following accomplishment of the requirements of this paragraph. (d) Airplanes on which the modification required by paragraph (c) of this AD is accomplished within the compliance time specified in paragraph (b) of this AD are not required to accomplish the actions required by paragraph (b). Alternative Methods of Compliance (e) 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 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 (f) 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 (g) The modification shall be done in accordance with BFGoodrich Aerospace Service Bulletin 3-1439-32-13, dated August 20, 1993; or BFGoodrich Aerospace Service Bulletin 3-1398-32-16, dated August 20, 1993, as applicable. 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 BFGoodrich Aerospace, Aircraft Wheels and Brakes, P.O. Box 340, Troy, Ohio 45373. 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. (h) This amendment becomes effective on October 20, 1999. Issued in Renton, Washington, on September 2, 1999. Dorenda D. Baker, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 99-23474 Filed 9-14-99; 8:45 am] BILLING CODE 4910-13-P