# AD 66-22-04: Mercury Clutches

- Type: Airworthiness directive
- Status: Current
- Products: Hiller UH-12D, UH-12L, UH-12L4, UH-12E and UH-12E-L
- Effective: September 2, 1966
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Amendment: 39-280
- Registered aircraft: 132 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/FC8EDB0E0552BAE386256A38005F8464.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/66-22-04

## The airworthiness directive

66-22-04 HILLER: Amdt. 39-280 Part 39 Federal Register September 2, 1966. Applies to Model UH-12D, UH-12E, UH-12E-L, UH-12L, and UH-12L4 Helicopters Equipped With Clutches, Mercury Clutch Corporation P/N's 4578-6 and 4692-6, Clutch Serial Numbers 8584 through 9317.

Compliance required within the next 100 hours' time in service after the effective date of this AD, unless already accomplished.

To prevent failures of the mercury clutch due to cracking at the inner corners of driver lug slots in the side plates, accomplish the following:

  (a) Visually inspect the side plates for cracks using at least 8-power magnification.

  (b) If cracks are found, replace clutch before further flight with a clutch of the same part number that has been inspected in accordance with this AD and found free of cracks.

(Fairchild Hiller Service Information Letters Nos. 3052 and 5009, dated July 20, 1966, pertain to this subject).

This directive effective September 2, 1966.

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 4H11](https://openairdocs.org/tcds/4H11): Siam Hiller Holdings Inc.; names 2 of 2 models: UH-12E, UH-12E-L
- [TCDS H1WE](https://openairdocs.org/tcds/H1WE): Siam Hiller Holdings Inc.; names 2 of 2 models: UH-12L4, UH-12L
- [TCDS 4H10](https://openairdocs.org/tcds/4H10): Siam Hiller Holdings Inc.; names 1 of 1 models: UH-12D

## 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: 132 (132 by airframe model, 0 by engine model)
- Makers: Hiller 129, Hiller-Osborn 2, Hiller-Rogerson Helicopter 1

Models with the most aircraft:

- [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 103 aircraft (airframe model)
- [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d): 22 aircraft (airframe model)
- [Hiller UH-12L4](https://openairdocs.org/model/hiller-uh-12l4): 3 aircraft (airframe model)
- [Hiller-Osborn UH-12D](https://openairdocs.org/model/hiller-osborn-uh-12d): 2 aircraft (airframe model)
- [Hiller UH-12E-L](https://openairdocs.org/model/hiller-uh-12e-l): 1 aircraft (airframe model)
- [Hiller-Rogerson Helicopter UH12E](https://openairdocs.org/model/hiller-rogerson-helicopter-uh12e): 1 aircraft (airframe model)

All 7 models: https://openairdocs.org/ad/66-22-04/models.md
Every aircraft: https://openairdocs.org/ad/66-22-04/aircraft.md

Its text cites no advisory circulars or STCs.

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