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 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 occurs first (Table 2)

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 cylinders.

SERVICE INSTRUCTION NUMBER 1037 Y

SUBJECT

Approved Pistons, Rings, Cylinders, and Gasket Set Application for Use on Lycoming Aircraft Engines

DATE

August 25, 2021

MODELS AFFECTED

All Lycoming opposed series aircraft engines in Table 1

TIME OF COMPLIANCE

When installing new rings, pistons, valves, and cylinders

SERVICE LETTER NO. L287

Increased Fuel Economy and Improved Manifold Pressure Stability

DATE POSTED:

August 17, 2021

TO:

Owners and Operators of Lycoming TEO-540-C1A

REASON FOR PUBLICATION:

Announcement to TEO-540-C1A operators for the availability of the new ECU calibration and components to increase the fuel economy and improve the manifold pressure stability. 

SERVICE INSTRUCTION NO. 1280 D

DATE:

July 20, 2021

SUBJECT:

Rotator Type Intake Valves

Service Bulletin No. 642A
Incorrect Piston and Ring Combination

June 16, 2021

MODELS AFFECTED

O-235-C, E & H series, and Factory Cylinder Kit P/N 05K23039

TIME OF COMPLIANCE

Within the next 10 hours of operation or next scheduled maintenance event, whichever occurs first.

REASON FOR REVISION: Deleted NOTICE “Only cylinders that …”. Added CAUTION and instructions for cylinder replacement before the Procedure section. Revised Step 5 in the Procedure section. Revised title and Step 1 in the Warranty Instructions

SERVICE INSTRUCTION NO. 1569 B

DATE:

April 21, 2020

SUBJECT:

Installation, Operation, and Maintenance of Lycoming Electronic Ignition System (EIS)

MODELS AFFECTED:

Lycoming 4 and 6-Cylinder piston aircraft engines

TIME OF COMPLIANCE:

At the owner/operator’s discretion.

REASON FOR REVISION:

Revised the SUBJECT line. Formatted pages 4 through 18 to indicate separation between Installation, Operation, and Maintenance chapters. Revised Table 2 – Troubleshooting Guide.

SERVICE LETTER NO. L284

Blemish on Cylinder Barrel

DATE:

March 17, 2021

TO:

All Owners and Operators of Lycoming O-235 Series engines

REASON FOR PUBLICATION:

This Service Letter is in response to reports of a blemish in the black oxide coating of P/N 16A26616 Cylinder Assemblies.

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 will maintain the engine's compliance with ASTM F2339.