Service Instruction No. 1125 E

Alternate Crankcase Parting Surface Sealants

Publications
DATE

April 28, 2026

MODELS AFFECTED

All Lycoming opposed cylinder engines

TIME OF COMPLIANCE

During engine assembly

REASON FOR REVISION

Reformatted the entire document to include additional approved methods of sealing the crankcase. Inform customers of approved replacements for No. 4 Perfect Seal Sealant. Clarify that “00” silk thread is the correct size of thread to be used. Added approved alternate methods for applying sealant and thread. Updated manufacturer of RTV-102.

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