# AD 78-25-08 R3: Turbine Rotor - Type: Airworthiness directive - Status: Current - Products: Honeywell International TPE331-1, TPE331-1U, TPE331-1UA, TPE331-2, TPE331-2U, TPE331-2UA, TPE331-3, TPE331-3U, TPE331-3UW, TPE331-3W, TPE331-5, TPE331-5U and 2 more - Effective: June 12, 1980 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: 39-3787 - Registered aircraft: 562 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/ABD6FD7D4F604AC086256825006F0975.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/78-25-08-R3 ## The airworthiness directive 78-25-08 R3 AIRESEARCH MANUFACTURING COMPANY OF ARIZONA: Amendment 39-3367 as amended by Amendment 39-3389 and 39-3607 is further amended by Amendment 39-3787. Applies to AiResearch Model TSE331-3 and TPE331-1, -2, -3, -5, -6 series engines. Compliance required as indicated. To prevent destructive overspeed of the turbine rotor in the event of any one of several single engine failures in the main reduction gear drive accomplish the following: (a) Within the next 3100 hours' time in service after July 1, 1979, or at the next overhaul after July 1, 1979, or prior to December 31, 1985, whichever comes first, unless already accomplished, incorporate the modified engine fuel control drive gear train in the main reduction gear box of the TSE331-3U and TPE331-1, -2, -3U, -3UW, -5, and -6 series engines in accordance with AiResearch Service Bulletin TPE331-72-0061, revision 1, dated December 18, 1978 or revision 2 dated October 18, 1979. Torque sensor assembly P/N 3101726-2 may be used in place of P/N 3101726-1. Installation of torque sensor assembly P/N 3101726-2 is per paragraph 2.E of AiResearch Service Bulletin TPE331-72-0232, Revision 1, dated December 5, 1979. (b) Equivalent procedures may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region. (c) Special flight permits may be issued per FAR 21.197 and 21.199 to authorize operation of aircraft to a base where this modification required by this AD may be performed. Amendment 39-3367 became effective January 19, 1979. Amendment 39-3389 became effective January 8, 1979. Amendment 39-3607 became effective November 19, 1979. This Amendment 39-3787 becomes effective June 12, 1980. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E4WE](https://openairdocs.org/tcds/E4WE): Honeywell Aerospace US LLC; names 8 of 48 models: TPE331-6U, TPE331-6, TPE331-3, TPE331-5, TPE331-3UW, TPE331-5U, TPE331-3U, TPE331-3W - [TCDS E3WE](https://openairdocs.org/tcds/E3WE): Honeywell Aerospace US LLC; names 6 of 6 models: TPE331-1UA, TPE331-2UA, TPE331-1U, TPE331-2U, TPE331-2, TPE331-1 ## 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: 562 (0 by airframe model, 562 by engine model) - Makers: Mitsubishi 106, Cessna 104, Ayres 52, Rockwell International 48, Swearingen 42, Fairchild 39, Beech 21, Gulfstream AM Corp Comm Div 21, Aero Commander 20, Short Bros. & Harland 17 Models with the most aircraft: - [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series): 492 aircraft (engine model) - [Honeywell TPE331-SER series](https://openairdocs.org/engine/honeywell-tpe331-ser-series): 28 aircraft (engine model) - [Garrett TPE331-5](https://openairdocs.org/engine/garrett-tpe331-5): 7 aircraft (engine model) - [Garrett TPE331-6](https://openairdocs.org/engine/garrett-tpe331-6): 6 aircraft (engine model) - [Garrett TPE331-1](https://openairdocs.org/engine/garrett-tpe331-1): 5 aircraft (engine model) - [AiResearch TPE331-1](https://openairdocs.org/engine/airesearch-tpe331-1): 3 aircraft (engine model) - [Garrett TPE331-2](https://openairdocs.org/engine/garrett-tpe331-2): 3 aircraft (engine model) - [Honeywell TPE331-2](https://openairdocs.org/engine/honeywell-tpe331-2): 3 aircraft (engine model) - [Honeywell TPE331-6](https://openairdocs.org/engine/honeywell-tpe331-6): 3 aircraft (engine model) - [AiResearch TPE331-2](https://openairdocs.org/engine/airesearch-tpe331-2): 2 aircraft (engine model) - [AiResearch TPE331-6](https://openairdocs.org/engine/airesearch-tpe331-6): 2 aircraft (engine model) - [Alliedsign TPE331-6](https://openairdocs.org/engine/alliedsign-tpe331-6): 2 aircraft (engine model) - [Honeywell TPE331-5](https://openairdocs.org/engine/honeywell-tpe331-5): 2 aircraft (engine model) - [AiResearch TPE331-3U](https://openairdocs.org/engine/airesearch-tpe331-3u): 1 aircraft (engine model) - [AiResearch TPE331-5](https://openairdocs.org/engine/airesearch-tpe331-5): 1 aircraft (engine model) - [Honeywell TPE331-1](https://openairdocs.org/engine/honeywell-tpe331-1): 1 aircraft (engine model) - [Honeywell TPE331-3U](https://openairdocs.org/engine/honeywell-tpe331-3u): 1 aircraft (engine model) All 18 models: https://openairdocs.org/ad/78-25-08-R3/models.md Every aircraft: https://openairdocs.org/ad/78-25-08-R3/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.