- Effective
- October 3, 1973
- Models
- DHC-6-1, DHC-6-100, DHC-6-200, DHC-6-300
- Data sheet
- TCDSA9EA
- Registered aircraft
- 88 matched by model
- Product
- Aircraft · Small airplane
- Amendment
- 39-1725
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 | 060bae27…964f16c | FAA DRS (API key needed) |
On this page
The airworthiness directive
73-20-05 de HAVILLAND: Model DHC-6. Amdt. 39-1725. Applies to de Havilland Model DHC-6 Twin Otter Floatplanes, all Series, certificated in all categories, equipped with Canadian Aircraft Products Model 12000A or 12000B Floats installed prior to Float Serial No. 71.
1. Compliance is required within the next ten hours in service from the effective date of this Airworthiness Directive, unless already accomplished.
To prevent loosening and subsequent pullout failure of certain float to fuselage bolts, comply with accomplishment instruction of de Havilland Service Bulletin 6/296, Revision A, dated May 11, 1973, or an equivalent alteration approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.
This amendment is effective October 3, 1973.
Affected TCDS · 1
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 88
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1966 | 1 |
|---|---|
| 1967 | 5 |
| 1968 | 7 |
| 1969 | 11 |
| 1970 | 2 |
| 1971 | 1 |
| 1973 | 3 |
| 1974 | 6 |
| 1975 | 1 |
| 1976 | 4 |
| 1977 | 6 |
| 1978 | 1 |
| 1979 | 3 |
| 1980 | 5 |
| 1981 | 3 |
| 1982 | 1 |
| 1984 | 1 |
| 1985 | 2 |
25 with no year recorded