Service Instruction No. 1442 A

Supersedes Service Instruction No. 1442

March 28, 2011


All Lycoming piston engines with dual magneto accessory housing


At next overhaul or evidence of a filter element collapse

This Service Instruction identifies a new spring, P/N 05S21021 that replaces spring P/N 55C21021 in the oil filter bypass valve. This replacement is to be done during overhaul or if oil filter element collapse occurs during cold starts.

Improved Oil Filter Bypass Valve
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Get It Exchanged
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Use our Engine Exchange Program to order a new, rebuilt, or overhauled engine to experience more airtime and less downtime.
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