Service Instruction No. 1423 A

Supersedes Service Instruction No. 1423

May 13, 2016


All Lycoming engines using Thermostatic Oil Cooler Bypass Valve Part Number (P/N) 75944


Before next flight REASON FOR REVISION: Loctite® procedure for crimp nut is no longer valid.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: Thermostatic oil cooler bypass valve part number P/N 53E22144 now supersedes P/N 75944 when it is necessary to replace bypass valve P/N 75944 if it is damaged, its crimp nut (Figure 1) is loose, or for any other reason.

Thermostatic Oil Cooler Bypass Valve Part Number
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