# AD 74-13-05: Connecting Rod Assemblies

- Type: Airworthiness directive
- Status: Current
- Products: Lycoming Engines IGO-540-A1A, IGO-540-A1B, IGO-540-A1C, IGO-540-B1A, IGO-540-B1B, IGO-540-B1C, IGSO-540-A1A, IGSO-540-A1C, IGSO-540-A1D, IGSO-540-A1E, IGSO-540-A1F, IGSO-540-B1A and 1 more
- Effective: June 21, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Amendment: 39-1876
- Registered aircraft: 58 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/ABB97F0CBB1B1DB28625682A00723E2B.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-13-05

## The airworthiness directive

74-13-05 AVCO LYCOMING: Amendment 39-1876. Applies to all IGO-540 series engines except IGO- 540 series engines with serials Nos. 311-49 and subsequent; and to all IGSO-540 series engines except IGSO-540 series engines with serials Nos. 2558-50 through 2563-50, 2565-50 through 2582-50, 2584-50 through 2589-50, 2591-50 through 2602-50, 2606-50 through 2631-50, 2637-50, 2640-50, 2647-50 through 2652-50, 2657-50 through 2692-50, 2694-50 through 2713-50, 2718-50 through 2727-50, 2730-50 through 2750-50, 2752-50 and subsequent; and except all IGO and IGSO-540 series engines overhauled (also known as remanufactured) by Lycoming after October 29, 1970. Compliance required as indicated after the effective date of this AD, unless already accomplished. To prevent failures of connecting rod assemblies P/N 72606, P/N 73174, and P/N 75548, accomplish the following: (a) Engines with connecting rod assemblies that have accumulated 400 hours or more in service since new or overhaul must have the connecting rod assemblies replaced with new connecting rod assembly, P/N 77450, within the next 50 hours in service. (b) Engines that have connecting rod assemblies with less than 400 hours in service since new or overhauled must have the connecting rod assemblies replaced with new connecting rod assembly, P/N 77450, within the next 100 hours in service. (c) Upon request, with substantiating data submitted through an FAA maintenance inspector, the compliance time may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. NOTE. Lycoming Service Bulletin No. 351A covers this subject. This amendment is effective June 21, 1974.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [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 6 of 6 models: IGO-540-B1B, IGO-540-B1A, IGO-540-B1C, IGO-540-A1A, IGO-540-A1C, IGO-540-A1B

## 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: 58 (0 by airframe model, 58 by engine model)
- Makers: Aero Commander 22, Beech 19, Piper 9, Cessna 2, Mooney 2, Dornier 1, Hiller 1, Maule 1, Pilatus 1

Models with the most aircraft:

- [Lycoming IGSO-540-B1A](https://openairdocs.org/engine/lycoming-igso-540-b1a): 48 aircraft (engine model)
- [Lycoming IGO-540-B1A](https://openairdocs.org/engine/lycoming-igo-540-b1a): 9 aircraft (engine model)
- [Lycoming IGO-540-A1C](https://openairdocs.org/engine/lycoming-igo-540-a1c): 1 aircraft (engine model)

All 3 models: https://openairdocs.org/ad/74-13-05/models.md
Every aircraft: https://openairdocs.org/ad/74-13-05/aircraft.md

Its text cites no advisory circulars or STCs.

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