Service Bulletin No. 639

Inspection of Rocker Arm, Part Number LW-15014

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Service Bulletin No. 639 Inspection of Rocker Arm, Part Number LW-15014

January 17, 2020

MODELS AFFECTED

O-320-H2AD, O, LO, TO, LTO-360-E1A6D new, rebuilt, or overhauled engines shipped from Lycoming since June 2017 with less than 500 hours of operation or engines with less than 500 hours of operation since rocker arm replacement.

TIME OF COMPLIANCE

At next scheduled oil change, then every 50 hours until 500 hours of engine operation.

This Service Bulletin is in response to field reports of damaged rocker arms found during an investigation of reported engine roughness. Lycoming has initiated an investigation into these instances. Until root cause and corrective action can be determined, as a precaution Lycoming is requesting the following inspections be completed at 50-hour intervals and any cracking found reported to Lycoming.

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