# AD 72-21-04: Magnetos

- Type: Airworthiness directive
- Status: Current
- Products: Lycoming Engines HIO-360-D1A
- Effective: October 13, 1972
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Amendment: 39-1532
- Registered aircraft: 431 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/B60C8A68BFFE902C8625682A00540ACE.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/72-21-04

## The airworthiness directive

72-21-04 AVCO LYCOMING: Amdt. 39-1532. Applies to HIO-360-D1A model engines installed on Hughes Model 269C and 300C helicopters. Compliance required as indicated after effective date of this AD. To prevent possible failures of the Bendix S4LN-1208 magnetos, P/N 10-349285-5, accomplish the following: 1. Within the next 50 hours time in service and at each 50 hours time in service thereafter, inspect and lubricate the magneto distributor bushing of both magnetos in accordance with Lycoming Service Bulletin No. 336B or later revision or equivalent procedure approved by Chief, Engineering and Manufacturing Branch, FAA, Eastern Region. 2. Within the next 100 hours time in service and at each 100 hours time in service thereafter, replace those parts in the left magneto with the parts contained in Bendix Kit No. 10-391320 or equivalent FAA-approved parts. 3. 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. This amendment is effective October 13, 1972.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1E10](https://openairdocs.org/tcds/1E10): Lycoming Engines; names 1 of 89 models: HIO-360-D1A

## 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: 431 (0 by airframe model, 431 by engine model)
- Makers: Schweizer 127, Enstrom 115, Hughes 111, Enstrom Helicopter 31, Cessna 3, Schweizer RSG 3, Bellanca 2, Pitts Special 2, Andrews 1, Beech 1

Models with the most aircraft:

- [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series): 336 aircraft (engine model)
- [Lycoming HI0-360 series](https://openairdocs.org/engine/lycoming-hi0-360-series): 54 aircraft (engine model)
- [Lycoming HIO-360-D1A](https://openairdocs.org/engine/lycoming-hio-360-d1a): 41 aircraft (engine model)

All 3 models: https://openairdocs.org/ad/72-21-04/models.md
Every aircraft: https://openairdocs.org/ad/72-21-04/aircraft.md

Its text cites no advisory circulars or STCs.

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