2001-24-12: Helical Torquemeter Gearshaft Assembly

2001-24-12 Rolls-Royce Corporation (formerly Allison Engine Company): Amendment 39-12529. Docket No. 2001-NE-38-AD. Supersedes AD 2001-20-51. Applicability This airworthiness directive (AD) is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) models 250-C20, -C20B, -C20F, -C20J, -C20R, -C20R/1, -C20R/2, -C20S, and -C20W turboshaft engines, and 250-B17, -B17C, -B17D, -B17E, -B17F, -B17F/1, and -B17F/2 turboprop engines. These engines are used on, but not limited to Aerospatiale AS355; Agusta A109; A109A, A109C; Bell 206B, 206L, 206LT; Enstrom TH28; McDonnell Douglas 500C, 500D, 500E, 520N; Rogerson-Hiller FH1100; Schweizer TH330; Soloy Conversions Bell 47/47G, Hiller UH-12; American Jet Industries/Cessna 402, 414; and ASTA/GAF Nomad N-22 aircraft. Note 1: This AD applies to each engine 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 engines 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) 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 Compliance with this AD is required as indicated, unless already done. To prevent uncontained release of power turbine blades and disk fragments caused by engine overspeed, resulting in an uncommanded engine shutdown, engine fire, and damage to the aircraft, do the following: (a) Before further flight, remove helical torquemeter gearshaft assemblies part numbers (P/N's) 23035299 and 23038191 that have accumulated 100 hours or less time-since-new(TSN). Replace with a serviceable helical torquemeter gearshaft assembly. (b) After the receipt of this AD, do not install any helical torquemeter gearshaft assembly P/N 23035299 or 23038191 that has accumulated 100 hours or less TSN. Definition (c) For the purposes of this AD, the following helical torquemeter gearshaft assemblies are considered serviceable parts: (1) P/N's 23035299 and 23038191 that have greater than 100 hours TSN. (2) An assembly with a P/N other than P/N's 23035299 and 23038191. Alternative Methods of Compliance (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, Chicago Aircraft Certification Office. Operators must submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Chicago Aircraft Certification Office. Note 2: Information concerningthe existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Chicago Aircraft Certification Office. Special Flight Permits (e) Special flight permits may be issued in accordance with 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be done. Effective Date of This AD (f) This amendment becomes effective December 19, 2001.