- Effective
- January 1, 1971
- Models
- 47, 47B, 47B3, 47D, 47D1, 47E and 18 more
- Registered aircraft
- 490 matched by model
- Product
- Aircraft · Rotorcraft
- Amendment
- 39-1137
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 | 22 KB | 4ab4fd9b…f7fbf17 | FAA DRS (API key needed) |
On this page
The airworthiness directive
70-08-02 BELL: Amendment 39-968 as amended by Amendment 39-1137 Applies to all Bell Model 47 Series Helicopters and all other helicopters incorporating any of the following tail rotor drive shaft assemblies:
47-644-172-3
47-644-180-1 47-644-186-1 47-644-180-5 47-644-187-5 47-644-214-1 47-644-187-11
Compliance required no later than March 1, 1971; however, replacement is recommended at the next 1200-hour overhaul.
To prevent failure from internal corrosion, remove and replace all tail rotor drive shaft assemblies installed on applicable helicopters as indicated below in accordance with the applicable maintenance and overhaul manual:
Remove Replace With 47-644-172-3 47-644-172-9 47-644-180-1 47-644-180-9 47-644-180-5 47-644-180-11 47-644-214-1 47-644-214-9 47-644-186-1 47-644-186-5 47-644-187-5 47-644-187-17 47-644-187-11 47-644-187-19
(Bell Service Bulletin No. 47-145, Rev. B, dated March 26, 1970, pertains to this matter) Amendment 39-968 effective May 9, 1970.
This amendment, 39-1137, becomes effective January 1, 1971.
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