AD 69-25-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | GO-435-C2A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-435-C2A2 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-A1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-B | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-B1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-B1B | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-B1C | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-B1D | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C1B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C1D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C2C6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C2D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C2E6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-C3A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-D1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-E1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F2A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F2D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F3A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F3B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F4A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F4B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-F6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G1B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G1D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G1H6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G1J6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G2D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GO-480-G2F6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-A1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-A1C6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-A2A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1C6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1E6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1F6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1G6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B1J6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B2C6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B2D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B2G6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | GSO-480-B2H6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGO-540-A1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGO-540-A1B | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGO-540-B1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGO-540-B1B | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGO-540-B1C | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1A6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1B6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1C6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1D6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1E6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1F6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-480-A1G6 | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-A1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-A1C | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-A1D | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-A1E | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-A1F | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-B1A | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
| engine | Lycoming Engines | IGSO-540-B1C | LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines |
Unsafe Condition
Failure of the reduction gear assembly due to improper torque on the pinion cage attaching nut and insufficient oil slinger design.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect torque on the reduction gearing pinion cage attaching nut. Depending on torque reading, either replace components and adjust torque to 400 ft.-lbs. or disassemble, inspect components, and replace oil slinger and housing. Replace spline nut with an approved hexagonal nut. Stamp suffix (-1) on reduction gear housing if oil slinger P/N 77454 is used.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Prior to the accumulation of 600 hours in service or 100 hours after the effective date of this AD whichever comes later for GO-435, IGO-540, and IGSO-540 engines; and prior to the accumulation of 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 engines.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Lycoming Engines models GO-435-C2A, GO-480, GSO-480, IGSO-480, IGO-540, and IGSO-540 type engines using specific reduction gear assemblies (spline type 72875, 72879; flange type 69346, 70412, 71803; and 72782, 74900, 75679, 76494, 77731).
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Reduction Gear Assemblies
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_69-25-08.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 69-25-08 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines Subject: Reduction Gear Assemblies Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/19/1970 Make: Lycoming Engines Model: GO-435-C2A | GO-435-C2A2 | GO-480-A1A | GO-480-B | GO-480-B1A6 | GO-480-B1B | GO-480-B1C | GO-480-B1...Show more Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 69-25-08 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-938 AD NUMBER: 69-25-08 SUBJECT HEADING: LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines ACTION: SUMMARY: DATES: Effective February 19, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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 pinion cage 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 Bulletin No. 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. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_69-25-08.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 69-25-08 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines Subject: Reduction Gear Assemblies Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/19/1970 Make: Lycoming Engines Model: GO-435-C2A | GO-435-C2A2 | GO-480-A1A | GO-480-B | GO-480-B1A6 | GO-480-B1B | GO-480-B1C | GO-480-B1...Show more Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 69-25-08 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-938 AD NUMBER: 69-25-08 SUBJECT HEADING: LYCOMING ENGINES Model GO-435-C2A, GO-480, GSO-480 and IGSO-480, and IGO-540 and IGSO-540 type Engines ACTION: SUMMARY: DATES: Effective February 19, 1970. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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 pinion cage 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 Bulletin No. 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. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.