# AD 91-24-02: Main Rotor Drive Shaft - Type: Airworthiness directive - Status: Current - Products: Turbomeca Arriel 1B, Arriel 1D and Arriel 1D1 - Effective: February 21, 1992 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: 39-8087 - Docket: 91-ANE-35 - Registered aircraft: 202 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5C673B06845259478625684D0069955F.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/91-24-02 ## The airworthiness directive 91-24-02 TURBOMECA: Amendment 39-8087, Docket No. 91-ANE-35. Applicability: Turbomeca Arriel 1B, 1D, Arriel 1D, and Arriel 1D1 turboshaft engines, installed on but not limited to, Aerospatiale AS350 Ecureuil aircraft. Compliance: Required as indicated, unless already accomplished. To prevent free wheel clutch failure and the inability to transmit power from the engine to the main rotor drive shaft, accomplish the following: (a) For engines that have not incorporated the modifications contained in either Turbomeca Service Document 72.292.0140 (Modification TU 211), dated June 14, 1990, or Turbomeca Service Document 72.292.0141 (Modification TU 212), dated July 13, 1990, and have a free wheel assembly serial number (S/N) of 793 or higher; or a S/N less than 793 and have had a maintenance action performed on the free wheel assembly, accomplish the following: (1) Install a free wheel clutch in accordance with Turbomeca Service Document 72.292.0141 (Modification TU 212),dated July 13, 1990, within 20 days from the effective date of this AD. (2) Install a free wheel shaft in accordance with Turbomeca Service Bulletin 292.72.0146 (Modification TU 221), dated May 8, 1991, within 20 days from the effective date of this AD. (3) Engines equipped with free wheel assemblies having a S/N lower than 793, that have not had a maintenance action performed on the free wheel assembly, are not required to incorporate the above modifications. NOTE: Information regarding free wheel clutch assembly S/N and free wheel clutch repair history may be found on the equipment Log Card and in the engine logbook. (b) For engines that have incorporated the modifications contained in Turbomeca Service Document 72.292.0140 (Modification TU 211), dated June 14, 1990, comply with paragraphs (b)(1) and (b)(2) of this AD. For engines that have incorporated Turbomeca Service Document 72.292.0141 (Modification TU 212), dated July 13, 1991, comply with paragraph (b)(2) only,as follows: (1) Install a free wheel clutch in accordance with the requirements of Turbomeca Service Document 72.292.0141 (Modification TU 212), dated July 13, 1990, at next shop visit or by March 31, 1992, whichever occurs first. (2) Install a free wheel shaft in accordance with the requirements of Turbomeca Service Bulletin 292.72.0146 (Modification TU 221), dated May 8, 1991, at next shop visit or by March 31, 1992, whichever occurs first. (c) For the purpose of this AD, a shop visit is defined as exposure of the free wheel assembly at a shop capable of performing the modification. (d) For the purpose of this AD, maintenance action is defined as any maintenance performed on any free wheel assembly component. (e) 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. (f) Upon submission of substantiating data by an owner or operator through an FAA Inspector (maintenance, avionics, or operations, as appropriate), an alternate method of compliance with the requirements of this AD or adjustments to the compliance times specified in this AD may be approved by the Manager, Engine Certification Office, Engine and Propeller Directorate, Aircraft Certification Service, FAA, 12 New England Executive Park, Burlington, Massachusetts. (g) The modification shall be done in accordance with the following Turbomeca service documents: DOCUMENT NO. PAGE NO. DATE 292.72.0146 1-7 August 5, 1991 Total Pages: 7 72.292.0141 1-4 July 13, 1990 Total Pages: 4 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 Turbomeca, Technical Publications Department, 64511 Bordes Cedex, France. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, Room 311, 12 New England Executive Park, Burlington, Massachusetts, or atthe Office of the Federal Register, 1100 L Street, NW, Room 8401, Washington, DC. This amendment (39-8087, AD 91-24-02) becomes effective on February 21, 1992. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E19EU](https://openairdocs.org/tcds/E19EU): Safran Helicopter Engines, S.A.S.; names 3 of 16 models: Arriel 1D, Arriel 1D1, Arriel 1B ## 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: 202 (0 by airframe model, 202 by engine model) - Makers: Eurocopter 118, American Eurocopter 32, Aerospatiale 21, Airbus Helicopters 10, Eurocopter France 9, Airbus Helicopters Deutschland 6, Eurocopter Deutschland 3, S N I A S 2, Sikorsky 1 Models with the most aircraft: - [Turbomeca ARRIEL-1D1](https://openairdocs.org/engine/turbomeca-arriel-1d1): 150 aircraft (engine model) - [Turbomeca ARRIEL series](https://openairdocs.org/engine/turbomeca-arriel-series): 31 aircraft (engine model) - [Turbomeca ARRIEL-1B](https://openairdocs.org/engine/turbomeca-arriel-1b): 18 aircraft (engine model) - [Safran ARRIEL-1D1](https://openairdocs.org/engine/safran-arriel-1d1): 3 aircraft (engine model) All 4 models: https://openairdocs.org/ad/91-24-02/models.md Every aircraft: https://openairdocs.org/ad/91-24-02/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.