95-21-03: Engine Fire Pull Switch Assembly

95-21-03 LEARJET: Amendment 39-9388. Docket 95-NM-178-AD. Applicability: Model 31A airplanes, serial numbers 31-093 through 31-108 inclusive; and Model 60 airplanes, serial numbers 60-034 through 60-061 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 (d) of this AD 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 theunsafe 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. Compliance: Required as indicated, unless accomplished previously. To prevent electrical failure of the microswitches in the engine fire pull switch assembly, which could result in the inability of the flight crew to shut down certain systems or to arm the fire extinguishers, or inadvertent shutdown of one or both engines, accomplish the following: (a) For Model 31A airplanes: Within 50 hours time-in-service after the effective date of this AD, perform an inspection to identify the serial numbers of the left-hand (pilot) and right-hand (copilot) engine fire pull switch assemblies in accordance with Learjet Alert Service Bulletin SB A31-26-3, dated July 14, 1995. (1) If the serial number of the assembly is not identified as 2326, 2363 through 2377 inclusive, or 3000 through 3019 inclusive: No further action is required by this AD. (2) If the serial number of the assembly is identified as 2326, 2363 through 2377 inclusive, or 3000 through 3019 inclusive: Prior to further flight, replace the engine fire pull switch assembly with a serviceable assembly in accordance with the alert service bulletin. (b) For Model 60 airplanes: Within 50 hours time-in-service after the effective date of this AD, perform an inspection to identify the serial numbers of the left-hand (pilot) and right-hand (copilot) engine fire pull switch assemblies in accordance with Learjet Alert Service Bulletin SB A60-26-1, dated July 14, 1995. (1) If the serial number of the assembly is not identified as 106 through 168 inclusive: No further action is required by this AD. (2) If the serial number of the assembly is identified as 106 through 168 inclusive: Prior to further flight, replace the engine fire pull switch assembly with a serviceable assembly in accordance with the alert servicebulletin. (c) As of the effective date of this AD, no person shall install on any airplane an engine fire pull switch assembly having a serial number identified in paragraph (c)(1) or (c)(2) of this AD, as applicable, unless such serial number is preceded by the letters "RS" and accompanied by a repair date code later than June 1, 1995. (1) For Model 31A airplanes: Serial numbers 2326, 2363 through 2377 inclusive, and 3000 through 3019 inclusive. (2) For Model 60 airplanes: Serial numbers 106 through 168 inclusive. (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, Wichita Aircraft Certification Office (ACO), FAA, Small 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, Wichita ACO. NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO. (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. (f) The inspection and replacement shall be done in accordance with Learjet Alert Service Bulletin SB A31-26-3, dated July 14, 1995, and Learjet Alert Service Bulletin SB A60-26-1, dated July 14, 1995. 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 Gates Learjet, Mid-Continent Airport, P.O. Box 7707, Wichita, Kansas 67277. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Wichita Aircraft Certification Office, Small Airplane Directorate, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (g) This amendment becomes effective on October 26, 1995.