- Effective
- June 18, 1968
- Models
- 250-C10B (T63-A-5A), 250-C18, 250-C18A, 250-C18B, 250-C18C, 250-C19
- Data sheet
- TCDSE4CE
- Registered aircraft
- 84 matched by model
- Product
- Engine
- Amendment
- 39-612
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 | 19 KB | f998f695…d5faad0 | FAA DRS (API key needed) |
On this page
The airworthiness directive
68-12-06 ALLISON: Amdt. 39-612. Applies to Models 250-C18, 250-C18A, 250-C18B, 250-C18C, 250- C19 and 250-C10B engines. Before further flight of any aircraft equipped with one of the Allison model engines listed above, unless already accomplished, modify the sixth stage compressor blades in these engines in accordance with Allison Commercial Engine Bulletin No. 250 CEB-48, dated June 11, 1968, or any other method approved by the Chief, Engineering and Manufacturing Branch, Central Region. Further flight beyond the point where an aircraft equipped with one of these engines is grounded pursuant to this Airworthiness Directive, may be conducted only in accordance with Federal Aviation Regulation 21.197. This amendment becomes effective June 18, 1968.
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 84
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1960 | 1 |
|---|---|
| 1962 | 4 |
| 1964 | 1 |
| 1965 | 2 |
| 1966 | 4 |
| 1967 | 1 |
| 1968 | 3 |
| 1969 | 1 |
| 1970 | 1 |
| 1972 | 2 |
| 1973 | 1 |
| 1974 | 1 |
| 1976 | 5 |
| 1977 | 2 |
| 1978 | 2 |
| 1979 | 1 |
| 1980 | 4 |
| 1981 | 5 |
| 1982 | 1 |
| 1984 | 1 |
| 1985 | 1 |
| 1986 | 1 |
| 1988 | 1 |
| 1992 | 2 |
| 1994 | 2 |
| 1996 | 7 |
| 1997 | 3 |
| 1998 | 2 |
| 1999 | 2 |
| 2000 | 6 |
| 2002 | 3 |
| 2004 | 2 |
| 2005 | 1 |
8 with no year recorded