AD 78-12-09
final rule
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | O-320-H1AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H1BD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H2AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H2BD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H3AD | AVCO LYCOMING Model O-320-H Series Engines |
| engine | Lycoming Engines | O-320-H3BD | AVCO LYCOMING Model O-320-H Series Engines |
Unsafe Condition
Crankshaft gear assembly failure due to insufficient hardness of the crankshaft gear teeth.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Remove and replace the crankshaft assembly with crankshaft assembly part number LW-15917 per AVCO Lycoming Service Bulletin No. 422 or FAA-approved equivalent. Equivalent methods require approval from the FAA Eastern Region's Engineering and Manufacturing Branch.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
before further flight except that the aircraft may be flown in accordance with FAR 21.197 to a location where this AD may be accomplished
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
AVCO Lycoming Model O-320-H1AD, O-320-H1BD, O-320-H2AD, O-320-H2BD, O-320-H3AD, O-320-H3BD engines with specific serial numbers listed in the AD, including ranges like L-1122-76 through L-1129-76 and others as enumerated.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Crankshaft Gear Assembly
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_78-12-09.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 78-12-09 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: AVCO LYCOMING Model O-320-H Series Engines Subject: Crankshaft Gear Assembly Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/20/1979 Make: Lycoming Engines Model: O-320-H1AD | O-320-H1BD | O-320-H2AD | O-320-H2BD | O-320-H3AD | O-320-H3BD Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 78-12-09 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3414 AD NUMBER: 78-12-09 SUBJECT HEADING: AVCO LYCOMING Model O-320-H Series Engines ACTION: SUMMARY: DATES: Effective February 20, 1979. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 78-12-09 AVCO LYCOMING: Amendment 39-3238 as amended by Amendment 39-3414. Applies to O-320-H series engines with the following serial numbers, unless already accomplished. L-103-76, L-104-76, L-272-76, L-283-76, L-288-76, L-290-76, L-336-76, L-337-76, L-341-76, L-404-76, L-431-76, L-468-76, L-469-76, L-471-76, L-494-76, L-548-76, L-589-76, L-590-76, L-592-76, L-650-76, L-684-76, L-689-76, L-698-76, L-736-76, L-737-76, L-738-76, L-743-76, L-754-76, L-763-76, L-768-76, L-769-76, L-772-76, L-774-76, L-777-76, L-778-76, L-802-76, L-824-76, L-834-76, L-846-76, L-903-76, L-904-76, L-929-76, L-940-76, L-945-76, L-948-76, L-949-76, L-1054-76, L-1115-76, L-1119-76, L-1122- 76 THROUGH L-1129-76, L-1131-76 THROUGH L-1134-76, L-1144-76, L-1156-76, L-1181-76, L-1186- 76, L-1191-76, L-1200-76, L-1205-76, L-1207-76, L-1237-76, L-1255-76, L-1304-76, L-1305-76, L-1352-76, L-1354-76, L-1374-76, L-1375-76, L-1379-76, L-1460-76, L-1476-76, L-1489-76, L-1492-76, L-1513-76, L-1568-76, L-1577-76, L-1626-76, L-1630-76, L-1639-76, L-1644-76, L-1657-76, L-1658-76, L-1665-76, L-1668-76, L-1678-76, L-1679-76, L-1687-76, L-1693-76, L-1694-76, L-1697-76, L-1795-76, L-1796-76, L-1824-76, L-1825-76, L-1826-76, L-1870-76, L-1885-76, L-1934-76, L-2002-76, L-2007-76, L-2016-76, L-2025-76 THROUGH L-2032-76, L-2041-76, L-2047-76, L-2065-76 THROUGH L-2068-76, L-2071-76 THROUGH L-2077-76, L-2115-76, L-2148-76, L-2157-76, L-2159-76 THROUGH L-2163-76, L-2165-76, L-2167-76, L-2168-76, L-2171-76, L-2174-76 THROUGH L-2182-76, L-2189-76, L-2190-76, L-2191-76, L-2192-76, L-2198-76, L-2260-76, L-2293-76, L-2294-76, L-2308-76, L-2338-76, L-2339-76, L-2340-76, L-2343-76, L-2344-76, L-2350-76, L-2365-76, L-2556-76, L-2596-76, L-2635-76, L-2636-76, L-2637-76, L-2644-76, L-2666-76, L-2697-76, L-2728-76, L-2731-76, L-2758-76, L-2762-76, L-2763-76, L-2774-76, L-2777-76, L-2782-76, L-2784-76, L-2790-76, L-2816-76, L-2832-76, L-2837-76, L-2842-76, L-2843-76, L-2845-76, L-2857-76, L-2908-76, L-2914-76, L-2921-76, L-2922-76, L-2924-76, L-2930-76, L-2932-76 THROUGH L-2938-76, L-2942-76, L-2947-76, L-2948-76, L-2962-76, L-2963-76, L-2966-76, L-2975-76, L-2980-76, L-2985-76, L-2987-76, L-2988-76, L-2989-76, L-2992-76, L-2999-76, L-3004-76, L-3010-76, L-3016-76, L-3034-76, L-3035-76, L-3041-76, L-3047-76, L-3063-76, L-3067-76, L-3068-76, L-3155-76, L-3170-76, L-3172-76, L-3240-76, L-3262-76, L-3288-76, L-3289-76, L-3291-76, L-3292-76, L-3293-76, L-3295-76, L-3296-76, L-3308-76, L-3313-76, L-3319-76, L-3384-76, L-3395-76 THROUGH L-3400-76, L-3402-76, L-3403-76, L-3404-76, L-3406-76, L-3411-76, L-3412-76, L-3413-76, L-3414-76, L-3428-76, L-3467-76, L-3551-76, RL-114-76, RL-124-76, RL-133-76, RL-162-76, RL-176-76, RL-186-76, RL-205-76, RL-249-76, RL-254-76, RL-328-76, RL-332-76, RL-351-76, RL-367-76, RL-384-76, RL-408-76, RL-416-76, RL- 418-76, RL-419-76, RL-435-76, RL-442-76, RL-443-76, RL-477-76, RL-510-76, RL-543-76, RL-550-76, RL-612-76, RL-652-76, RL-673-76, RL-695-76, RL-832-76, RL-1022-76, RL-1082-76, RL-1173-76, RL-1218-76, RL-214-76. Compliance required before further flight except that the aircraft may be flown in accordance with FAR 21.197 to a location where this AD may be accomplished. a. To prevent possible crankshaft gear failure, remove and replace the crankshaft assembly and install crankshaft assembly P/N LW-15917 in accordance with AVCO Lycoming Service Bulletin No. 422, dated March 24, 1978, or FAA approved equivalent. b. Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Amendment 39-3238 was effective June 20, 1978. This Amendment 39-3414 is effective February 20, 1979. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_78-12-09.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 78-12-09 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: AVCO LYCOMING Model O-320-H Series Engines Subject: Crankshaft Gear Assembly Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/20/1979 Make: Lycoming Engines Model: O-320-H1AD | O-320-H1BD | O-320-H2AD | O-320-H2BD | O-320-H3AD | O-320-H3BD Product Type: Engine 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: 78-12-09 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-3414 AD NUMBER: 78-12-09 SUBJECT HEADING: AVCO LYCOMING Model O-320-H Series Engines ACTION: SUMMARY: DATES: Effective February 20, 1979. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 78-12-09 AVCO LYCOMING: Amendment 39-3238 as amended by Amendment 39-3414. Applies to O-320-H series engines with the following serial numbers, unless already accomplished. L-103-76, L-104-76, L-272-76, L-283-76, L-288-76, L-290-76, L-336-76, L-337-76, L-341-76, L-404-76, L-431-76, L-468-76, L-469-76, L-471-76, L-494-76, L-548-76, L-589-76, L-590-76, L-592-76, L-650-76, L-684-76, L-689-76, L-698-76, L-736-76, L-737-76, L-738-76, L-743-76, L-754-76, L-763-76, L-768-76, L-769-76, L-772-76, L-774-76, L-777-76, L-778-76, L-802-76, L-824-76, L-834-76, L-846-76, L-903-76, L-904-76, L-929-76, L-940-76, L-945-76, L-948-76, L-949-76, L-1054-76, L-1115-76, L-1119-76, L-1122- 76 THROUGH L-1129-76, L-1131-76 THROUGH L-1134-76, L-1144-76, L-1156-76, L-1181-76, L-1186- 76, L-1191-76, L-1200-76, L-1205-76, L-1207-76, L-1237-76, L-1255-76, L-1304-76, L-1305-76, L-1352-76, L-1354-76, L-1374-76, L-1375-76, L-1379-76, L-1460-76, L-1476-76, L-1489-76, L-1492-76, L-1513-76, L-1568-76, L-1577-76, L-1626-76, L-1630-76, L-1639-76, L-1644-76, L-1657-76, L-1658-76, L-1665-76, L-1668-76, L-1678-76, L-1679-76, L-1687-76, L-1693-76, L-1694-76, L-1697-76, L-1795-76, L-1796-76, L-1824-76, L-1825-76, L-1826-76, L-1870-76, L-1885-76, L-1934-76, L-2002-76, L-2007-76, L-2016-76, L-2025-76 THROUGH L-2032-76, L-2041-76, L-2047-76, L-2065-76 THROUGH L-2068-76, L-2071-76 THROUGH L-2077-76, L-2115-76, L-2148-76, L-2157-76, L-2159-76 THROUGH L-2163-76, L-2165-76, L-2167-76, L-2168-76, L-2171-76, L-2174-76 THROUGH L-2182-76, L-2189-76, L-2190-76, L-2191-76, L-2192-76, L-2198-76, L-2260-76, L-2293-76, L-2294-76, L-2308-76, L-2338-76, L-2339-76, L-2340-76, L-2343-76, L-2344-76, L-2350-76, L-2365-76, L-2556-76, L-2596-76, L-2635-76, L-2636-76, L-2637-76, L-2644-76, L-2666-76, L-2697-76, L-2728-76, L-2731-76, L-2758-76, L-2762-76, L-2763-76, L-2774-76, L-2777-76, L-2782-76, L-2784-76, L-2790-76, L-2816-76, L-2832-76, L-2837-76, L-2842-76, L-2843-76, L-2845-76, L-2857-76, L-2908-76, L-2914-76, L-2921-76, L-2922-76, L-2924-76, L-2930-76, L-2932-76 THROUGH L-2938-76, L-2942-76, L-2947-76, L-2948-76, L-2962-76, L-2963-76, L-2966-76, L-2975-76, L-2980-76, L-2985-76, L-2987-76, L-2988-76, L-2989-76, L-2992-76, L-2999-76, L-3004-76, L-3010-76, L-3016-76, L-3034-76, L-3035-76, L-3041-76, L-3047-76, L-3063-76, L-3067-76, L-3068-76, L-3155-76, L-3170-76, L-3172-76, L-3240-76, L-3262-76, L-3288-76, L-3289-76, L-3291-76, L-3292-76, L-3293-76, L-3295-76, L-3296-76, L-3308-76, L-3313-76, L-3319-76, L-3384-76, L-3395-76 THROUGH L-3400-76, L-3402-76, L-3403-76, L-3404-76, L-3406-76, L-3411-76, L-3412-76, L-3413-76, L-3414-76, L-3428-76, L-3467-76, L-3551-76, RL-114-76, RL-124-76, RL-133-76, RL-162-76, RL-176-76, RL-186-76, RL-205-76, RL-249-76, RL-254-76, RL-328-76, RL-332-76, RL-351-76, RL-367-76, RL-384-76, RL-408-76, RL-416-76, RL- 418-76, RL-419-76, RL-435-76, RL-442-76, RL-443-76, RL-477-76, RL-510-76, RL-543-76, RL-550-76, RL-612-76, RL-652-76, RL-673-76, RL-695-76, RL-832-76, RL-1022-76, RL-1082-76, RL-1173-76, RL-1218-76, RL-214-76. Compliance required before further flight except that the aircraft may be flown in accordance with FAR 21.197 to a location where this AD may be accomplished. a. To prevent possible crankshaft gear failure, remove and replace the crankshaft assembly and install crankshaft assembly P/N LW-15917 in accordance with AVCO Lycoming Service Bulletin No. 422, dated March 24, 1978, or FAA approved equivalent. b. Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Amendment 39-3238 was effective June 20, 1978. This Amendment 39-3414 is effective February 20, 1979. 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.
Related Airworthiness Directives
2026-04-11 Recurring
final ruleAirworthiness Directives; Lycoming Engines
Unsafe Condition: Reports of connecting rod failures, which resulted in uncontained engine failure and in-flight shutdowns.
2024-21-02 Recurring
final ruleAirworthiness Directives; Lycoming Engines
Unsafe Condition: Connecting rod failures, which resulted in uncontained engine failure and in-flight shutdowns (IFSDs), due to degradation of the connecting rod small end bushings.
2012-03-07
final ruleAirworthiness Directives; Lycoming Engines Reciprocating Engines
Unsafe Condition: A 'machined-from-billet' HA-6 carburetor having a loose mixture control sleeve that rotated in the carburetor body causing restriction of fuel and power loss.
2007-04-19R1
final ruleAirworthiness Directives; Superior Air Parts, Inc. (SAP), Cylinder Assemblies Part Numbers Series: SA47000L, SA47000S, SA52000, SA55000, SL32000W, SL32000WH, SL32006W, SL36000TW, SL36000W, and SL36006W
Unsafe Condition: Cylinder separation that can lead to engine failure, a possible engine compartment fire, and damage to the airplane due to cylinder head fatigue failure and separation at the head-to-barrel threade...