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. 1585 DATE: November 19, 2021 SUBJECT: Oil Cooler Bypass Valve Assembly Replacement MODELS AFFECTED: Lycoming TEO-540-C1A TIME OF COMPLIANCE: At next scheduled maintenance event, or earlier at owner’s discretion

DOCUMENT PART NO. MM-TEO-540-C1A DATE RELEASED: November 2021 TITLE: TEO-540-C1A Maintenance Manual Rev 4 DOCUMENT PART NUMBER: MM-TEO-540-C1A Rev 4

TEO-540-C1A Engine Installation & Operations Manual DOCUMENT PART NO. IOM-TEO-540-C1A REV 4 DOCUMENT PART NO. IOM-TEO-540-C1A DATE RELEASED: November 2021 TITLE: TEO-540-C1A Installation & Operations Manual Rev 4 DOCUMENT PART NUMBER: IOM-TEO-540-C1A Rev 4

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