# AD 69-25-08: Reduction Gear Assemblies - Type: Airworthiness directive - Status: Current - Products: Lycoming Engines GO-435-C2A, GO-435-C2A2, GO-480-A1A, GO-480-B, GO-480-B1A6, GO-480-B1B, GO-480-B1C, GO-480-B1D, GO-480-C1B6, GO-480-C1D6, GO-480-C2C6, GO-480-C2D6 and 52 more - Effective: February 19, 1970 - Superseded by: Nothing supersedes this AD - Product type: Engine - Amendment: 39-938 - Registered aircraft: 400 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/6EF923DC553107FB86256E0100547849.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/69-25-08 ## The airworthiness directive 69-25-08 LYCOMING ENGINES: Amdt. 39-892 as amended by Amendment 39-938. Applies to Lycoming GO-435-C2A, GO-480, GSO-480 and IGSO-480 type engines using spline type reduction gear assemblies 72875 and 72879, GO-480 and GSO-480 type engines using flange type reduction gear assemblies 69346, 70412 and 71803 and IGO-540 and IGSO-540 type engines using reduction gear assemblies 72782, 74900, 75679, 76494 and 77731. Compliance required unless already accomplished prior to the accumulation of six hundred (600) hours in service or 100 hours after the effective date of this AD whichever comes later for the GO-435, IGO-540 and IGSO-540 type engines and prior to the accumulation of seven hundred (700) hours in service or 100 hours after the effective date of this AD whichever comes later for GO-480, GSO-480 and IGSO-480 type engines. To prevent failure of the reduction gear assembly a one time inspection is to be accomplished as follows: a. Check torque on reduction gearing pinioncage attaching nut. 1. If found to be in excess of 50 ft.-lbs. remove, inspect for damage and replace the oil retaining housing if necessary. During assembly comply with part (b) using a new lockplate and a pinion cage attaching nut torque of 400 ft.-lbs. When the assembly is disassembled replace thrust bearing oil slinger P/N 68319 with P/N 77454. 2. If found to be less than 50 ft.-lbs. disassemble the assembly and insure that all components meet approved specifications and replace the thrust bearing oil slinger P/N 68319 and P/N 77454 and the oil retaining housing. During assembly comply with part (b) using a new lockplate and a pinion cage attaching nut torque of 400 ft.-lbs. b. If the pinion cage is secured with a spline nut it must be replaced with an approved hexagonal nut. c. If the assembly has been rebuilt using thrust bearing oil slinger P/N 77454, stamp the suffix (-1) to the part number on the reduction gear housing. Lycoming Service BulletinNo. 319A and Lycoming Service Instruction No. 1210A pertain to this subject. Amendment 39-892 effective December 17, 1969. This Amendment (39-938) is effective February 19, 1970. ## Affected data sheets (5) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS E-275](https://openairdocs.org/tcds/E-275): Lycoming Engines; names 29 of 33 models: GO-480-F3A6, GO-480-C1B6, GO-480-G1J6, GO-480-C2C6, GO-480-F1A6, GO-480-G2F6, GO-480-B1C, GO-480-C3A6… - [TCDS E-284](https://openairdocs.org/tcds/E-284): Lycoming Engines; names 21 of 23 models: IGSO-480-A1A6 (O-480-3), IGSO-480-A1B6, GSO-480-B2H6, GSO-480-B1F6, GSO-480-B1E6, GSO-480-B1C6, IGSO-480-A1C6, GSO-480-A1C6… - [TCDS 1E7](https://openairdocs.org/tcds/1E7): Lycoming Engines; names 7 of 8 models: IGSO-540-A1F, IGSO-540-B1A, IGSO-540-A1C, IGSO-540-A1A, IGSO-540-B1C, IGSO-540-A1D, IGSO-540-A1E - [TCDS 1E11](https://openairdocs.org/tcds/1E11): Lycoming Engines; names 5 of 6 models: IGO-540-B1B, IGO-540-B1A, IGO-540-B1C, IGO-540-A1A, IGO-540-A1B - [TCDS E-228](https://openairdocs.org/tcds/E-228): Lycoming Engines; names 2 of 20 models: GO-435-C2A, GO-435-C2A2 ## 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: 400 (0 by airframe model, 400 by engine model) - Makers: Beech 135, Helio 73, Aero Commander 53, Grumman 26, Republic 19, Piaggio 15, Focke-Wulf 12, Piper 9, Pilatus 8, Dornier 7 Models with the most aircraft: - [Lycoming GO-480 series](https://openairdocs.org/engine/lycoming-go-480-series): 246 aircraft (engine model) - [Lycoming GSO&IGSO-480 series](https://openairdocs.org/engine/lycoming-gso-igso-480-series): 59 aircraft (engine model) - [Lycoming IGSO-540-B1A](https://openairdocs.org/engine/lycoming-igso-540-b1a): 48 aircraft (engine model) - [Lycoming GO-480-B1A6](https://openairdocs.org/engine/lycoming-go-480-b1a6): 10 aircraft (engine model) - [Lycoming IGO-540-B1A](https://openairdocs.org/engine/lycoming-igo-540-b1a): 9 aircraft (engine model) - [Lycoming GO-480-G1D6](https://openairdocs.org/engine/lycoming-go-480-g1d6): 7 aircraft (engine model) - [Lycoming GO-435-C2A2](https://openairdocs.org/engine/lycoming-go-435-c2a2): 5 aircraft (engine model) - [Lycoming GO-480-G2D6](https://openairdocs.org/engine/lycoming-go-480-g2d6): 3 aircraft (engine model) - [Lycoming GSO-480-B1J6](https://openairdocs.org/engine/lycoming-gso-480-b1j6): 3 aircraft (engine model) - [Lycoming GO-435-C2A](https://openairdocs.org/engine/lycoming-go-435-c2a): 2 aircraft (engine model) - [Lycoming GO-480-B](https://openairdocs.org/engine/lycoming-go-480-b): 1 aircraft (engine model) - [Lycoming GO-480-B1D](https://openairdocs.org/engine/lycoming-go-480-b1d): 1 aircraft (engine model) - [Lycoming GO-480-F4A6](https://openairdocs.org/engine/lycoming-go-480-f4a6): 1 aircraft (engine model) - [Lycoming GO-480-G1A6](https://openairdocs.org/engine/lycoming-go-480-g1a6): 1 aircraft (engine model) - [Lycoming GO-480-G1B6](https://openairdocs.org/engine/lycoming-go-480-g1b6): 1 aircraft (engine model) - [Lycoming GO-480-G2F6](https://openairdocs.org/engine/lycoming-go-480-g2f6): 1 aircraft (engine model) - [Lycoming GSO-480-B1B6](https://openairdocs.org/engine/lycoming-gso-480-b1b6): 1 aircraft (engine model) - [Lycoming IGSO-480-A1E6](https://openairdocs.org/engine/lycoming-igso-480-a1e6): 1 aircraft (engine model) All 18 models: https://openairdocs.org/ad/69-25-08/models.md Every aircraft: https://openairdocs.org/ad/69-25-08/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.