AD 71-05-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | IO-360-A1A | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A1B | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A1B6 | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A1C | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A1D6 | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A2A | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A2B | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-A2C | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-C1A | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-C1B | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-C1C | AVCO LYCOMING Model IO-360-A and -C Series Engines |
| engine | Lycoming Engines | IO-360-C1D6 | AVCO LYCOMING Model IO-360-A and -C Series Engines |
Unsafe Condition
Shifting and possible failures of the crankcase main bearings
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect lubrication system for metal contaminants at specified intervals. If contaminants detected, remove number two cylinder to examine bearing position. Modify crankcase per service instructions or install straight dowels to eliminate inspections.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 10 hours in service after effective date for initial inspection; subsequent intervals depend on engine hours since new/overhaul (every 25 hours until 525 hours, then comply with (d) or (f); engines over 1150 hours must comply with (f) within 50 hours)
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
AVCO LyCOMING Model IO-360-A and -C series engines except S/N 7100-51A and subsequent, and engines overhauled by Lycoming after 26 January 1970 except specific listed serial numbers
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Crankcase Main Bearings
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_71-05-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-05-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: AVCO LYCOMING Model IO-360-A and -C Series Engines Subject: Crankcase Main Bearings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/13/1973 Make: Lycoming Engines Model: IO-360-A1A | IO-360-A1B | IO-360-A1B6 | IO-360-A1C | IO-360-A1D6 | IO-360-A2A | IO-360-A2B | IO-360-...Show more 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: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 71-05-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1589 AD NUMBER: 71-05-02 SUBJECT HEADING: AVCO LYCOMING Model IO-360-A and -C Series Engines ACTION: SUMMARY: DATES: Effective February 13, 1973. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-05-02 AVCO LYCOMING: Amdt. 39-1158 as amended by Amendment 39-1402, 39-1537 and 39-1550 is further amended by Amendment 39-1589. Applies to all IO-360-A and -C series engines except S/N 7100-51A and subsequent and except all engines overhauled (also known as remanufactured) by Lycoming after 26 January 1970 except S/N 354-51, 1049-51A, 3003-51A, 3281-51A, 6526-51A. To prevent shifting and possible failures of the crankcase main bearings, perform the following: (a) Engines that have accumulated less than 500 hours in service since new or overhaul must have the lubrication system inspected for metal contaminants within the next 10 hours in service after the effective date of this AD and every 25 hours in service until 525 hours in service are accumulated, at which time compliance with (d) or (f) is required. Inspection of the lubrication system consists of visual examination for minute particles of metal suspended in the oil, examination of the engine oil suction screen for presence of metal particles and the inspection of the external full flow oil filter for metal particles by cutting it open so that the pleated element can be unfolded and examined. (b) Engines that have accumulated 500 hours or more in service since new or overhaul must have the lubrication system inspected for metal contaminants within the next 10 hours in service after the effective date of this AD. Further, compliance with (d) or (f) is required within 25 hours in service after the effective date of this AD. (c) Compliance with (d) or (f) is required if metal contaminants are detected during the above inspections. (d) Remove number two position cylinder and examine visually the position of the center main bearing for shifting in accordance with the inspection procedure of Avco Lycoming Service Bulletin No. 327B or equivalent inspection approved by Chief, Engineering and Manufacturing Branch FAA, Eastern Region. Should shifting be detected, comply with paragraph (f). If the bearing has not shifted and no metal contaminants are detected after compliance with paragraph (a) or (b) the engine can be returned to service and the lubrication system must be inspected for contaminants every 50 hours in service thereafter. (e) Unless already accomplished, compliance with paragraph (f) is required within 50 hours in service after the effective date of this AD on engines that have accumulated 1150 hours or more in service since new or last overhaul. (f) Modify the crankcase as described in Lycoming Service Instructions No. 1123A or repair the crankcase as described in Lycoming Service Instructions No. 1112C, whichever is applicable, and install straight crankcase bearing dowels per Lycoming Service Bulletin No. 326 or equivalent repair or alteration approved by Chief, Engineering and Manufacturing Branch, FAA, Eastern Region. Compliance with the provisions of this paragraph eliminates the inspection requirements of this AD. (NOTE: The inspection of the lubrication system required by this AD constitutes preventive maintenance.) Amendment 39-1158 was effective February 23, 1971. Amendment 39-1402 was effective March 14, 1972. Amendment 39-1537 was effective October 17, 1972. Amendment 39-1550 was effective upon publication in the Federal Register. This amendment 39-1589 is effective February 13, 1973. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_71-05-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 71-05-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: AVCO LYCOMING Model IO-360-A and -C Series Engines Subject: Crankcase Main Bearings Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: 02/13/1973 Make: Lycoming Engines Model: IO-360-A1A | IO-360-A1B | IO-360-A1B6 | IO-360-A1C | IO-360-A1D6 | IO-360-A2A | IO-360-A2B | IO-360-...Show more 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: Updated RGL applicability to match AD applicability; CAR C-11-185 AIRWORTHINESS DIRECTIVES FINAL RULES: 71-05-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: 39-1589 AD NUMBER: 71-05-02 SUBJECT HEADING: AVCO LYCOMING Model IO-360-A and -C Series Engines ACTION: SUMMARY: DATES: Effective February 13, 1973. ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 71-05-02 AVCO LYCOMING: Amdt. 39-1158 as amended by Amendment 39-1402, 39-1537 and 39-1550 is further amended by Amendment 39-1589. Applies to all IO-360-A and -C series engines except S/N 7100-51A and subsequent and except all engines overhauled (also known as remanufactured) by Lycoming after 26 January 1970 except S/N 354-51, 1049-51A, 3003-51A, 3281-51A, 6526-51A. To prevent shifting and possible failures of the crankcase main bearings, perform the following: (a) Engines that have accumulated less than 500 hours in service since new or overhaul must have the lubrication system inspected for metal contaminants within the next 10 hours in service after the effective date of this AD and every 25 hours in service until 525 hours in service are accumulated, at which time compliance with (d) or (f) is required. Inspection of the lubrication system consists of visual examination for minute particles of metal suspended in the oil, examination of the engine oil suction screen for presence of metal particles and the inspection of the external full flow oil filter for metal particles by cutting it open so that the pleated element can be unfolded and examined. (b) Engines that have accumulated 500 hours or more in service since new or overhaul must have the lubrication system inspected for metal contaminants within the next 10 hours in service after the effective date of this AD. Further, compliance with (d) or (f) is required within 25 hours in service after the effective date of this AD. (c) Compliance with (d) or (f) is required if metal contaminants are detected during the above inspections. (d) Remove number two position cylinder and examine visually the position of the center main bearing for shifting in accordance with the inspection procedure of Avco Lycoming Service Bulletin No. 327B or equivalent inspection approved by Chief, Engineering and Manufacturing Branch FAA, Eastern Region. Should shifting be detected, comply with paragraph (f). If the bearing has not shifted and no metal contaminants are detected after compliance with paragraph (a) or (b) the engine can be returned to service and the lubrication system must be inspected for contaminants every 50 hours in service thereafter. (e) Unless already accomplished, compliance with paragraph (f) is required within 50 hours in service after the effective date of this AD on engines that have accumulated 1150 hours or more in service since new or last overhaul. (f) Modify the crankcase as described in Lycoming Service Instructions No. 1123A or repair the crankcase as described in Lycoming Service Instructions No. 1112C, whichever is applicable, and install straight crankcase bearing dowels per Lycoming Service Bulletin No. 326 or equivalent repair or alteration approved by Chief, Engineering and Manufacturing Branch, FAA, Eastern Region. Compliance with the provisions of this paragraph eliminates the inspection requirements of this AD. (NOTE: The inspection of the lubrication system required by this AD constitutes preventive maintenance.) Amendment 39-1158 was effective February 23, 1971. Amendment 39-1402 was effective March 14, 1972. Amendment 39-1537 was effective October 17, 1972. Amendment 39-1550 was effective upon publication in the Federal Register. This amendment 39-1589 is effective February 13, 1973. 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.