# AD 72-11-04: Failure Tail Rotor Drive Pins

- Type: Airworthiness directive
- Status: Current
- Products: Enstrom Helicopter Corporation, The F-28A
- Effective: June 1, 1972
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-1452
- Registered aircraft: 39 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/AC1B6B5B7D5DEB6C86256A38004D3A37.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/72-11-04

## The airworthiness directive

72-11-04 ENSTROM: Amdt. 39-1452. Applies to Model F-28A (Serial Numbers 1 through 83) helicopters.

Compliance: Required as indicated, unless already accomplished.

To prevent failure of tail rotor drive taper pins with subsequent loss of directional control, accomplish the following:

A) Unless Paragraph B has been accomplished, within 10 hours' time in service after the effective date of this AD visually inspect the 2 forward and 3 aft AN386 taper pins installed in the tail rotor drive shaft assembly for looseness. Prior to further flight replace all loose taper pins with AN386-2-8A taper pins acquired from either the Enstrom Factory Customer Service Department, or Enstrom Dealers in accordance with Enstrom Service Note No. 0011 dated March 29, 1972, or by any equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA, Great Lakes Region.

NOTE: Loose pins can be detected by:

1. Wiggling the pin with the fingers.

2. Grasping the tail rotor drive shaft with the hand and rotating the shaft back and forth while observing the movement of the pin in the mating hole.

3. Examining for loss of paint on the pin at the edge of the mating hole.

4. Examining for formation of a burr at the edge of the hole.

B) Within 25 hours' time in service after the effective date of this AD, replace all AN386 taper pins installed in the tail rotor drive shaft assembly with AN386-2-8A taper pins acquired from either the Enstrom Factory Customer Service Department, or Enstrom Dealers in accordance with Enstrom Service Note No. 0011 dated March 29, 1972, or by any equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA, Great Lakes Region.

This amendment becomes effective June 1, 1972.

## 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/72-11-04/models.md
Every aircraft: https://openairdocs.org/ad/72-11-04/aircraft.md

Its text cites no advisory circulars or STCs.

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