Service Bulletin No. 555 A

Supersedes Service Bulletin No. 555 and Supplement No. 2 to Service Bulletin No. 555

May 16, 2003

MODELS AFFECTED

New, factory rebuilt or factory overhaul engines listed in Table 1.

NOTE: Service Bulletin No. 555 also affects any engine that has had the following oil pump bodies field installed:

1. P/N 78528 shipped between 5/1/01 and 1/20/03.

2. P/N 78890 shipped between 9/17/01 and 1/20/03.

3. P/N 51A22618 shipped between 9/29/00 and 1/20/03.

TIME OF COMPLIANCE

Within next 50 hours of operation or next scheduled maintenance, whichever occurs first.

Lycoming has determined that the allen type pipe plug in the oil pump body must be inspected for proper torque. An improperly torqued plug may allow oil leakage and loss of oil pressure.