- Models
- 47, 47B, 47B3, 47D, 47D1, 47E and 18 more
- Registered aircraft
- 490 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 | 21 KB | 7ab211ac…a24a2d4 | FAA DRS (API key needed) |
On this page
The airworthiness directive
57-08-01 BELL: Applies to All 47 Series Helicopters With Tail Rotor Drive Shafts, P/N 47-644-115-1, 47-644-126-3, 47-644-172-3, 47-644-177-1, 47-644-179-7, 47-644-180-1, 47-644- 186-1, 47-644-187-1, 47-644-187-5, and 46-644-214-1, Having Less Than 100 Hours Service Time and All Spares of These Part Numbers.
Compliance required as indicated.
Due to suspected defective materials, the listed tail rotor drive shafts must be inspected for evidence of longitudinal cracks, as follows:
1. Inspect all spare shafts by magnaflux methods immediately.
2. Shafts installed on helicopters and having less than 100 hours service time must be thoroughly cleaned and inspected daily with at least a 10-power magnifying glass, and inspected by magnaflux methods not later than the next 10 flying hours. The daily inspections may be discontinued upon completion of the magnaflux inspection.
3. Spare shafts and helicopters delivered from Bell after April 15, 1957, have these inspections accomplished and may be identified by a double interlocking magnaflux stamp in approximately the centers of the shafts.
(This AD covers the same inspections required by CAA telegraphic instructions, dated April 12 and 17, 1957.)
Affected TCDS · 3
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 490
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1946 | 1 |
|---|---|
| 1947 | 10 |
| 1948 | 5 |
| 1949 | 3 |
| 1950 | 2 |
| 1951 | 7 |
| 1952 | 8 |
| 1953 | 8 |
| 1954 | 9 |
| 1955 | 7 |
| 1956 | 19 |
| 1957 | 18 |
| 1958 | 18 |
| 1959 | 10 |
| 1960 | 10 |
| 1961 | 9 |
| 1962 | 12 |
| 1963 | 20 |
| 1964 | 18 |
| 1965 | 20 |
| 1966 | 33 |
| 1967 | 28 |
| 1968 | 20 |
| 1969 | 12 |
| 1970 | 8 |
| 1971 | 12 |
| 1972 | 14 |
| 1973 | 10 |
| 1974 | 4 |
| 1975 | 2 |
| 1976 | 1 |
| 1979 | 1 |
| 1980 | 1 |
| 1981 | 1 |
| 2010 | 1 |
128 with no year recorded