AD 54-04-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | AC Spark Plug | LA-87 Spark Plugs | Airworthiness Directives; AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs |
Unsafe Condition
Use of AC LS-87 spark plugs in engines for which they are not approved may lead to engine failure.
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Required Actions
Remove AC LS-87 spark plugs from all engines except R-1820 and R-1830 engines of 1,200 HP or less. Limit LS-87 plugs on excepted engines to a maximum of 120 hours of service without reconditioning and remove those exceeding 120 hours.
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Compliance Time
prior to March 1, 1954
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Affected Aircraft
AC Spark Plug LA-87 spark plugs installed on all engines except Pratt and Whitney R-1830 and Wright R-1820 engines of 1,200 HP or less.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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