Service Instruction No. 1125 E

Publications
DATE RELEASED:

April 28, 2026

SUBJECT:

Alternate Crankcase Parting Surface Sealants

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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