- Effective
- October 5, 1978
- Models
- 336, 337, T337B, T337C, T337D, T337E and 12 more
- Registered aircraft
- 765 matched by model
- Product
- Appliance
- Amendment
- 39-3312
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 January 21, 2026.
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 | 6844b396…55bb4ea | FAA DRS (API key needed) |
On this page
The airworthiness directive
78-20-12 FIRESTONE AIRCRAFT TIRES: Amendment 39-3312. Applies to all Firestone size 18x5.5 Mach I, 10 Ply rating part number 00490, serial numbers having the first four numbers 0677, to be replaced by Firestone tire part number 00518 or other approved tire installed on, but not limited to, Lear Jet Models 23, 24, 25; Beech Models 99 series, B100, 200; Swearingen SA 226-TC and Cessna Models 336/337 or T-337 series aircraft.
a) Inspect for serial numbers having the first four numbers 0677 P/N 00490.
b) Replace with Firestone tires having serial numbers outside of this subject group or with Firestone tire P/N 00518 or with any other tire approved for these aircraft.
Obliterate TSO markings on tires identified in this AD to prevent future use on aircraft.
This amendment is effective October 5, 1978, as to all persons except those persons to whom it was made immediately effective by the airmail letter dated September 6, 1978, which contained this amendment.
Affected TCDS · 6
The type certificate data sheets for the models this AD names, matched by model and maker.
Registered aircraft · 765
Registered aircraft whose airframe or engine model this AD names. Matched by model only, so check each against the AD’s applicability.
| 1962 | 30 |
|---|---|
| 1963 | 101 |
| 1964 | 12 |
| 1965 | 41 |
| 1966 | 3 |
| 1967 | 19 |
| 1968 | 19 |
| 1969 | 18 |
| 1970 | 4 |
| 1971 | 2 |
| 1972 | 16 |
| 1973 | 29 |
| 1974 | 15 |
| 1975 | 24 |
| 1976 | 31 |
| 1977 | 37 |
| 1978 | 51 |
| 1979 | 64 |
| 1980 | 60 |
| 1981 | 41 |
| 1982 | 5 |
| 1983 | 4 |
| 1984 | 3 |
| 1995 | 1 |
| 2001 | 1 |
134 with no year recorded