# AD 90-12-05: Engine Overhaul - Type: Airworthiness directive - Status: Current - Products: Pratt & Whitney Canada PT6A-15AG, PT6A-27, PT6A-28, PT6A-29, PT6A-34 and PT6A-34AG - Effective: May 30, 1990 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: 39-6607 - Docket: 90-ANE-10 - Registered aircraft: 2,941 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0C9105EEFE9089DE86256846006D2D57.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/90-12-05 ## The airworthiness directive 90-12-05 PRATT & WHITNEY CANADA: Amendment 39-6607. Docket No. 90-ANE-10. Applicability: Pratt & Whitney Canada (PWC) PT6A series turbopropeller engines repaired by Gregory Flying Service/Airforce Turbine Service (hereafter identified as Gregory Flying Service), located in Tynan, Texas. The affected engines are identified by model and serial number as follows: MODEL SERIAL NO. MODEL SERIAL NO. PT6A-15AG PCE 14012 PT6A-34AG PCE 56433 PT6A-15AG PCE 14018 PT6A-34AG PCE 56466 PT6A-15AG PCE 14028 PT6A-34AG PCE 56471 PT6A-34 PCE 38093 PT6A-34AG PCE 56516 PT6A-28 PCE 40023 PT6A-34AG PCE 56522 PT6A-27 PCE 41704 PT6A-34AG PCE 56527 PT6A-28 PCE 51327 PT6A-34AG PCE 56612 PT6A-29 PCE 51426 PT6A-34AG PCE 56628 PT6A-34 PCE 56089 PT6A-34AG PCE 56650 PT6A-34AG PCE 56381 PT6A-34AG PCE 56717 PT6A-34AG PCE 56405 PT6A-34AG PCE 56773 Compliance: Required as indicated, unless already accomplished. To prevent the development of an unsafe condition which could result in an uncontained engine failure, accomplish the following: (a) Remove from service those engines identified above within the next 30 calendar days after the effective date of this AD. (b) Return to service engines removed from service in accordance with paragraph (a) by accomplishing either one of the two following requirements: (1) Accomplish a complete engine overhaul in accordance with the requirements of the appropriate PWC overhaul manual. (2) Submit to the FAA, Manager, Engine Certification Office, through the cognizant FAA Airworthiness Inspector, all the pertinent records identified below for review, and obtain a written FAA approval prior to returning an engine to service: (i) For the parts, sub-assemblies, accessories, or components of engines that were subjected to repair or maintenance activities during the last shop visit at Gregory Flying Service, provide the following: (1) A list of all life-limited components by serial number, service history, and their current status as required by FAR Part 135, Section 439, or FAR Part 91, Section 173, as appropriate, and records establishing the origin and/or the prior service history of the subject parts. (2) Records of accomplishment of the required inspections, checks, tests, as applicable, in accordance with PWC engine manual requirements that establish the components' airworthiness. (ii) All repair, maintenance, and inspection records, concerning the last shop visit at Gregory Flying Service, as required by FAR Part 135, Section 439, or FAR Part 91, Section 173, as appropriate. (iii) Substantiating evidence that the work performed during the last shop visit at Gregory Flying Service was done in accordance with FAA approved data as required by the FAR's. (iv) Engine acceptance test data or engine installed test data, accomplished after the repair, whichever is applicable. (v) A list by part number or serial number of any engine, part, sub-assembly, accessory, or component acquired from Gregory Flying Service that has been involved in an accident. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (Pub. L. 96-511) and have been assigned OMB Control No. 2120-0056. (c) Aircraft may be ferried in accordance with the provisions of FAR 21.197 and 21.199 to a base where the AD can be accomplished. (d) Upon submission of substantiating data by an owner or operator through an FAA Airworthiness Inspector, an alternate method of compliance with the requirements of this AD or adjustments to the compliance time specified in this AD may be approved by the Manager, Engine Certification Office, Engine and Propeller Directorate, Aircraft Certification Service, Federal Aviation Administration, 12 New England Executive Park, Burlington, Massachusetts 01803. This amendment (39-6607, AD 90-12-05) becomes effective on May 30, 1990. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E4EA](https://openairdocs.org/tcds/E4EA): Pratt & Whitney Canada Corp.; names 3 of 54 models: PT6A-29, PT6A-34AG, PT6A-15AG ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 2,941 (0 by airframe model, 2,941 by engine model) - Makers: Air Tractor 662, Beech 538, Cessna 435, Piper 237, Raytheon 236, Quest 138, Pilatus 120, Dehavilland 114, Socata 92, Kodiak 69 Models with the most aircraft: - [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series): 2,217 aircraft (engine model) - [Pratt & Whitney Canada PT6A-34AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-34ag): 269 aircraft (engine model) - [Pratt & Whitney Canada PT6A-34 series](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-34-series): 230 aircraft (engine model) - [Pratt & Whitney PT6 series](https://openairdocs.org/engine/pratt-whitney-pt6-series): 43 aircraft (engine model) - [Pratt & Whitney PT6A-34 series](https://openairdocs.org/engine/pratt-whitney-pt6a-34-series): 42 aircraft (engine model) - [Pratt & Whitney Canada PT6A-15AG](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-15ag): 40 aircraft (engine model) - [Pratt & Whitney Canada PT6A-27 series](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-27-series): 30 aircraft (engine model) - [Pratt & Whitney PT6A-27 series](https://openairdocs.org/engine/pratt-whitney-pt6a-27-series): 28 aircraft (engine model) - [Pratt & Whitney PT6A-28 series](https://openairdocs.org/engine/pratt-whitney-pt6a-28-series): 25 aircraft (engine model) - [Pratt & Whitney Canada PT6A-28 series](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-28-series): 12 aircraft (engine model) - [Pratt & Whitney Canada PT6 series](https://openairdocs.org/engine/pratt-whitney-canada-pt6-series): 3 aircraft (engine model) - [U/A Canada PT6A-34AG](https://openairdocs.org/engine/u-a-canada-pt6a-34ag): 2 aircraft (engine model) All 13 models: https://openairdocs.org/ad/90-12-05/models.md Every aircraft: https://openairdocs.org/ad/90-12-05/aircraft.md Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.