- Effective
- September 2, 1966
- Models
- UH-12D, UH-12L, UH-12L4, UH-12E, UH-12E-L
- Registered aircraft
- 132 matched by model
- Product
- Aircraft · Rotorcraft
- Amendment
- 39-280
Unofficial copy of the text in the FAA’s Dynamic Regulatory System. The FAA’s own copy is the authoritative one. DRS record last changed May 30, 2024.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
| File | Size | SHA-256 | Original |
|---|---|---|---|
| FAA DRS HTML | 20 KB | 888463d8…1ae483a | FAA DRS (API key needed) |
On this page
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 TCDS · 3
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 132
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1957 | 4 |
|---|---|
| 1958 | 4 |
| 1959 | 7 |
| 1960 | 8 |
| 1961 | 6 |
| 1962 | 12 |
| 1963 | 2 |
| 1964 | 10 |
| 1965 | 6 |
| 1966 | 3 |
| 1973 | 1 |
| 1975 | 3 |
| 1976 | 7 |
| 1977 | 4 |
| 1978 | 3 |
| 1979 | 3 |
| 1980 | 3 |
| 1981 | 3 |
| 1982 | 3 |
| 1993 | 1 |
| 1996 | 1 |
38 with no year recorded