- Models
- UH-12, UH-12A, UH-12B
- Registered aircraft
- 57 matched by model
- Product
- Aircraft · Rotorcraft
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 | e96e3b95…56463b4 | FAA DRS (API key needed) |
On this page
The airworthiness directive
53-09-03 HILLER: Applies to All UH-12, UH-12A, UH-12B, HTE-1, HTE-2, H-23A and H-23B Model Helicopters.
Compliance required as soon as possible but no later than the next 25-hour inspection and as indicated in part C below.
The following has been found necessary to prevent fatigue failure of the clevis head on the outboard tension torsion bar pins, P/N 51414-1:
A. Inspect P/N 51414-1 pins to determine the fillet radius under the clevis head. If radius is less than 0.030 inch the pin must be scrapped and replaced with a pin having at least 0.030-inch radius before further flight.
B. If radius is 0.030 or greater and the pin has less than 500 hours total time it may be reinstalled. If a featheredge is found at the base of the clevis it should be carefully removed.
C. All 51414-1 pins must be replaced when they have accumulated a total of 500 hours of flight time.
(Hiller Service Bulletin No. 36 covers this procedure.)
Affected TCDS · 2
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 57
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1949 | 3 |
|---|---|
| 1950 | 4 |
| 1951 | 3 |
| 1952 | 8 |
| 1953 | 6 |
| 1954 | 1 |
| 1955 | 3 |
| 1956 | 1 |
| 1960 | 1 |
| 1961 | 1 |
| 1962 | 1 |
| 1963 | 1 |
24 with no year recorded