2002-06-08: Third Stage Turbine Wheels

2002-06-08 Rolls-Royce Corporation: Amendment 39-12685. Docket No. 2001-NE-31-AD. Applicability: This airworthiness directive (AD) is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 250-C28, -C28B, and -C28C model engines with third stage turbine wheels part number (P/N) 6899383, listed by serial number (SN) in the following Table 1: Table 1.--SN's of Affected Third Stage Turbine Wheels HX91428R HX91489R HX91707R HX91456R HX91490R HX91708R HX91457R HX91492R HX91709R HX91458R HX91493R HX91710R HX91459R HX91494R HX91711R HX91461R HX91500R HX91712R HX91462R HX91501R HX91713R HX91464R HX91503R HX91714R HX914659 HX91504R HX91715R HX91465R HX91506R HX91721R HX91466R HX91507R HX91722R HX91467R HX91508R HX91726R HX91468R HX91510R HX91733R HX91469R HX91511R HX91735R HX91471R HX91512R HX91736R HX91472R HX91513R HX91738R HX91473R HX91519R HX91742R HX91474R HX91520R HX91744R HX91475RHX91522R HX91748R HX91477R HX91523R HX91749R HX91478R HX91524R HX91750R HX91480R HX91525R HX91754R HX91482R HX91526R HX91764R HX91483R HX91527R HX91765R HX91485R HX91528R HX91766R HX91486R HX91529R HX91767R HX91487R HX91530R HX91768R HX91488R HX91706R HX91769R Note.--These engines are installed on, but not limited to Bell Helicopter Textron 206L-1 helicopters. 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 (c) 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 an uncommanded shutdown of the engine due to fractures of third stage turbine blade tips and third stage turbine shrouds, do the following: (a) Remove from service the third stage turbine wheels, P/N 6899383, listed by SN in Table 1 of this AD, in accordance with the following Table 2: Table 2.--Removal Schedule For third stage turbine wheels on the effective date of this AD Remove by (1) With fewer than 3,000 cycles-since-new (CSN), and fewer than 1,500 hours time-since-new (TSN). 3,000 CSN or 1,500 hours TSN, whichever occurs earlier. (2) With between 3,000 and 6,000 CSN, and fewer than 1,500 hours TSN. 200 additional cycles, after the effective date of this AD. (3) With fewer than 3,000 CSN, and between 1,500 and 3,000 hoursTSN. 100 additional hours, after the effective date of this AD. (4) With between 3,000 and 6,000 CSN and between 1,500 and 3,000 hours TSN. 200 additional cycles or 100 additional hours, after the effective date of this AD, whichever occurs earlier. (5) With more than 6,000 CSN, or more than 3,000 hours TSN Before further flight. (b) After the effective date of this AD, do not install any third stage turbine wheels listed by SN in Table 1 of this AD. Thereafter, except as provided in paragraph (c) of this AD, no alternative cyclic life limits may be approved for the turbine wheels listed in Table 1 of this AD. Alternative Methods of Compliance (c) 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 (ACO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Chicago ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Chicago ACO. Special Flight Permits (d) 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 aircraft to a location where the requirements of this AD can be done. Effective Date (e) This amendment becomes effective on April 26, 2002.