SERVICE LETTER NO. L285 Change in cylinder configuration for O-235-C, -E, and -H Series engines DATE: August 25, 2021 TO: All Owners and Operators of Lycoming O-235-C, -E, and -H Series engines REASON FOR PUBLICATION: Lycoming supplied cylinders for O-235-C, -E, and -H Series engines were previously plain steel, straight-bore cylinders. This design has been replaced with nitrided, choke-bore...

Service Bulletin No. 643 Crankcase Nut Safety Wire Inspection September 16, 2021 MODELS AFFECTED Lycoming engines identified in Tables 1 and 2 TIME OF COMPLIANCE Aerobatic engines – within the next 10 hours of operation or next scheduled maintenance event, whichever occurs first (Table 1). Non-aerobatic engines - within the next 50 hours of operation or next scheduled maintenance event, whichever...

Service Bulletin No. 645 Small End Connecting Rod Bushing Inspection September 24, 2021 MODELS AFFECTED Engines with a serial number listed in Table 1 of this Service Bulletin TIME OF COMPLIANCE Within the next 10 hours of engine operation.

SERVICE INSTRUCTION NO. 1573E DATE POSTED: November 22, 2021 SUBJECT: Lycoming TEO-540 Engine Series Approved Engine Configurations MODELS AFFECTED: Refer to Table 1 TIME OF COMPLIANCE: As Required for Inspection/Maintenance/Replacement

SERVICE INSTRUCTION NO. 1582 A DATE: November 22, 2021 SUBJECT: Fuel Injector Replacement MODELS AFFECTED: Lycoming TEO-540-C1A TIME OF COMPLIANCE: At the first replacement of Fuel Injector P/N 61X26294-CT

Service Bulletin No. 647 Incorrect Markings on Service Tool# ST-310 December 14, 2021 MODELS AFFECTED Lycoming Engines that have been inspected using the Incorrectly Marked Tool TIME OF COMPLIANCE Upon receiving this Service Bulletin

SERVICE LETTER NO. L288 Alternate Bolt Locking of Wastegate Solenoid Valve DATE: December 16, 2021 TO: Owners and Operators of Lycoming TEO-540-C1A REASON FOR PUBLICATION: This Service Letter announces that the repetitive need to remove and install safety wire on the solenoid valve attaching bolt can be eliminated by usage of lock washer P/N STD-160 in combination with Loctite® 243 or equivalent.

SERVICE INSTRUCTION NO. 1586 DATE: December 2, 2021 SUBJECT: Oil Cooler Bypass Valve Assembly Replacement MODELS AFFECTED: Lycoming TEO-540-C1A TIME OF COMPLIANCE: At next scheduled oil change