AD 95-09-01 Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

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

Model 737-300, -400, and -500 series airplanes; line numbers 2137 through 2271, 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 use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Required as indicated, unless accomplished previously. To prevent the failure of the fireproof insulation topcoat installed on the firewalls for the thrust reverser fan cowls, which can result in degradation or loss of the firewall and lead to an uncontained engine fire, accomplish the following: (a) Within 30 months after the effective date of this AD, inspect the inner wall of the [[Page 20396]] fan duct cowl (the firewall) of the thrust reversers to determine the type of topcoat material installed, in accordance with Boeing Alert Service Bulletin 737-78A1056, dated August 11, 1994. (1) If the existing topcoat has silica fibers in it, no further action is required by this AD. (2) If the existing topcoat does not have silica fibers in it, prior to further flight, accomplish the application of the DC92-010 topcoat to the firewall of the thrust reversers in accordance with the service bulletin. (b) 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (c) 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. (d) The inspection and application shall be done in accordance with Boeing Alert Service Bulletin 737-78A1056, dated August 11, 1994. 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. (e) This amendment becomes effective on May 26, 1995. Issued in Renton, Washington, on April 14, 1995. John J. Hickey, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 95-9771 Filed 4-25-95; 8:45 am] BILLING CODE 4910-13-U