Supersedes Service Letter No. L197 January 19, 1988 Models Affected To all Owners and Operators of Textron Lycoming Piston Aircraft Engines In order to minimize valve sticking problems, procedures recommended in this Service Letter should be followed. Depending on the degree of intensity, sticking between the valve stem and guide can severely restrict the valve's opening and closing movements. A...

Supersedes Service Letter No. L192A January 19, 1988 Models Affected To all Owners and Operators of Lycoming Aircraft Engines. In many cases spark plug fouling resulting from the tetraethyl lead (TEL) in aviation fuels can be reduced or eliminated by proper operating techniques.

Supersedes Service Letter No. L185 A January 19, 1988 Models Affected To all Owners and Operators of Textron Lycoming Aircraft Engines We received many inquiries from the field expressing concern over the limited availability of 80/87 grade fuel and associated questions from use of higher leaded fuel in engines rated for grade 80/87 fuel. The leading fuel suppliers indicate that in some areas 80...

January 28, 1983 Models Affected To Owners and Operators of Lycoming Reciprocating Aircraft Engines. This Service Letter is to clarify Lycoming’s position on the fuel grades that are specified for use in our reciprocating engine models.

November 26,1971 Models Affected To all owners and operators of Avco Lycoming Aircraft Engines. As the use of spectrometric lubricating oil analysis has become more widespread in the field of general aviation, the problems of methods, procedures, schedules andinterpretation of data have become prevalent. This service letter is an attempt to clarify the subject and to define how lubricating oil...

Supersedes Service Instruction No. 1255 May 13, 2016 MODELS AFFECTED Lycoming engines using thermostatic oil cooler bypass valve TIME OF COMPLIANCE At 100-hour inspection or when high oil temperature is noted REASON FOR REVISION Updated bypass valve replacement part numbers; added respective detailed bypass valve replacement instructions for engines with oil pressure screens and oil filters This...

Supersedes Service Instruction No. 1301A May 13, 2016 MODELS AFFECTED All Lycoming aircraft engines TIME OF COMPLIANCE Any time a fuel line for a fuel injector, primer or fuel manifold are replaced REASON FOR REVISION Update part numbers Fuel lines are to be examined, typically every 100 hours of engine operation or sooner if instructed. If a fuel line is damaged, it is to be replaced with a new...

Supersedes Service Instruction No. 1423 May 13, 2016 MODELS AFFECTED All Lycoming engines using Thermostatic Oil Cooler Bypass Valve Part Number (P/N) 75944 TIME OF COMPLIANCE Before next flight REASON FOR REVISION: Loctite® procedure for crimp nut is no longer valid. New superseding part number for thermostatic oil cooler bypass valve. This revision of the Service Instruction identifies a change...

Supersedes Service Instruction No. 1523F March 16, 2016 MODELS AFFECTED Refer to Table 1 in attached Instruction TIME OF COMPLIANCE As Required for Replacement REASON FOR REVISION Added carburetor part numbers to Table 1 This Service Instruction identifies carburetors from specific manufacturers currently available for Lycoming engine models. Table 1 identifies the carburetor models, Lycoming part...