- Effective
- May 8, 1975
- Models
- UH-12D, UH-12L, UH-12L4, UH-12E, UH-12E-L
- Registered aircraft
- 132 matched by model
- Product
- Aircraft · Rotorcraft
- Amendment
- 39-2193
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 | 21 KB | cd0cfcfe…5cb8a43 | FAA DRS (API key needed) |
On this page
The airworthiness directive
75-10-01 HILLER: Amendment 39-2193. Applies to all UH-12D (Mil. H-23D, OH- 23D), UH-12E (Mil. H-23F, OH-23F, OH-23G), UH-12E-L, UH-12L and UH-12L4 helicopters certificated in all categories except those helicopters modified to incorporate Allison 250 series engines in accordance with Supplemental Type Certificate No. SH177WE or SH178WE.
Compliance required within 50 hours' time in service after the effective date of this AD unless already accomplished.
In order to prevent power loss due to slippage of the mercury clutch in the rotor drive system:
(a) Remove the existing placard reading "No further flight if clutch engagement time exceeds 25 seconds."
(b) Install decal placard, part number 81426-7, on the instrument panel in accordance with Hiller Service Letter 21-4 dated April 3, 1975. The placard is to read, "No further flight if clutch engagement time exceeds 20 seconds."
(c) Incorporate the Hiller Rotorcraft Flight Manual Revision dated April 15, 1975in the applicable rotorcraft flight manual.
Equivalent modifications may be approved by the Chief, Aircraft Engineering Division, FAA Western Region.
This supersedes Amendment 39-1462 (37 F.R. 11857), AD 72-13-4.
This amendment becomes effective May 8, 1975.
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