# AD 74-17-07: Main Rotor Gear Box

- Type: Airworthiness directive
- Status: Current
- Products: Enstrom Helicopter Corporation, The F-28A
- Effective: August 24, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-1925
- Registered aircraft: 39 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/1B10A139AFCC5A1186256A38004D3F12.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/74-17-07

## The airworthiness directive

74-17-07 ENSTROM: Amendment 39-1925. Applies to the following Enstrom Model F- 28A main rotor gearboxes, Serial Numbers: 03A, 016, 025, 041, 050, 063, 073, 082, 09-02-69, 08-001-72, and 20-001-72.

Compliance required as indicated unless already accomplished:

  (a) All main rotor gearboxes in this group with a total time since remanufacture of 100 hours or more must be returned to the Enstrom facility for teardown and inspection within the next 5 hours.

  (b) All main rotor gearboxes in this group with a total time since remanufacture of less than 100 hours should be returned to the Enstrom facility for teardown and inspection before accumulating 100 hours.

This amendment becomes effective August 24, 1974.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H1CE](https://openairdocs.org/tcds/H1CE): The Enstrom Helicopter Corporation; names 1 of 14 models: F-28A

## 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: 39 (39 by airframe model, 0 by engine model)
- Makers: Enstrom 38, Enstrom Helicopter 1

Models with the most aircraft:

- [Enstrom F-28A](https://openairdocs.org/model/enstrom-f-28a): 38 aircraft (airframe model)
- [Enstrom Helicopter F-28A](https://openairdocs.org/model/enstrom-helicopter-f-28a): 1 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/74-17-07/models.md
Every aircraft: https://openairdocs.org/ad/74-17-07/aircraft.md

Its text cites no advisory circulars or STCs.

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