AD 54-04-01
final rule
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 |
| appliance | 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.
AI-generated summary from the source AD text. Verify against the official source before acting.
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.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
prior to March 1, 1954
AI-generated summary from the source AD text. Verify against the official source before acting.
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.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Spark Plugs
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_54-04-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 54-04-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs Subject: Spark Plugs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: AC Spark Plug Model: LA-87 Spark Plugs Product Type: Appliance Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 54-04-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 54-04-01 SUBJECT HEADING: Airworthiness Directives; AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_54-04-01.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 54-04-01 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs Subject: Spark Plugs Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: AC Spark Plug Model: LA-87 Spark Plugs Product Type: Appliance Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 54-04-01 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 54-04-01 SUBJECT HEADING: Airworthiness Directives; AC SPARK PLUG: Applies to All Engines Equipped With AC LA-87 Spark Plugs ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.