SERVICE INSTRUCTION NO. 1009 BE Time Between Overhaul (TBO) Schedules DATE: April 24, 2020 SUBJECT: Time Between Overhaul (TBO) Schedules MODELS AFFECTED: Lycoming Engine Models Defined Herein REASON FOR REVISION: Added a new paragraph at the end of the Operating Hour Time Period TBO section. Added new engine model IO-390-D to Table 1. Revised Table 2 to include separate listings for engine model...

Special Service Publication No. SSP-110-2 Certificated Engine List DATE RELEASED: May 2020 TITLE: Certificated Engine List DOCUMENT PART NUMBER: SSP-110-2

Supersedes Service Instruction No. 1014M DATE: July 29, 2020 MODELS AFFECTED All Lycoming opposed series aircraft engines. TIME OF COMPLIANCE When preservation oil is removed or when lubricating oil is changed or added. REASON FOR UPDATE Updated lubrication oils and temperature ranges.

SUBJECT: Repair of Oil Cooler By-Pass Valve Seat DATE: April 26, 1986 MODELS AFFECTED: PART I: All Avco Lycoming piston engines equipped with a P/N 75944 oil cooler bypass valve. PART II: All Avco Lycoming direct drive engines that incorporate either a dual magneto drive accessory housing or a P/N 69510 oil pressure screen and temperature valve housing on an individual magneto drive accessory...

Service Instruction No. 1577 Intake Valve In-Service Data DATE: November 10, 2020 SUBJECT: Intake Valve In-Service Data MODELS AFFECTED: O-540-F1B5 engines with serial number ending with “-40E” installed in Robinson R44 Raven I and R44 Cadet helicopters TIME OF COMPLIANCE: During the next scheduled 50-hour inspection for engines with less than 500 hours since new, rebuild, overhaul, or cylinder...

Service Instruction No. 1579 Exhaust System Replacement Components DATE: November 20, 2020 SUBJECT: Exhaust System Replacement Components MODELS AFFECTED: TIO-540-AJ1A TIME OF COMPLIANCE: As required.

SERVICE LETTER NO. L282 Australian Fuel Testing DATE: December 11, 2020 TO: Australian Robinson R22 and R44 Owners and Operators REASON FOR PUBLICATION: This Service Letter transmits information pertaining to recent engine testing performed on Avgas grades used in Australia and the United States.

DATE RELEASED: February 19, 2021 TITLE: YO-233-B2A Maintenance Manual DOCUMENT PART NUMBER: MM-YO-233 (Supersedes Maintenance Manual LM-YO-233, dated June 2012)

SERVICE LETTER NO. L283 Alternate Ignition System DATE: February 19, 2021 TO: All Owners and Operators of Lycoming YO-233 Series engines REASON FOR PUBLICATION: This Service Letter is announcing the availability of an alternate ignition system to replace the Champion Aerospace Electronic Ignition System (Lycoming P/N 66K26674-Y) on YO-233 Series engines. Installing this alternate ignition system...