- Model
- LA-87 Spark Plugs
- Product
- Appliance
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 | 20 KB | 66118256…b84f92c | FAA DRS (API key needed) |
On this page
The airworthiness directive
54-04-01 AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs, Except Pratt and Whitney R-1830 Engines of 1,200 HP or Less and Wright R-1820 Engines of 1,200 HP or Less.
Compliance required prior to March 1, 1954.
A. In order to preclude possibilities of engine failure, when using AC LS-87 spark plugs in engines for which they are not approved, these spark plugs must be removed from all engines with the exceptions of the R-1820 having a T.O. rating of 1,200 h.p. or less and the R-1830 having a T.O. rating of 1,200 h.p. or less.
B. On R-1820 and R-1830 engines of 1,200 h.p. or less, the LS-87 plug is limited to a maximum of 120 hours of service with no reconditioning permitted. Plugs having over 120 hours must be removed from service.
This supersedes AD 49-26-02.