Service Instruction No. 1485 A

Supersedes Service Instruction No. 1485

July 2, 2003

MODELS AFFECTED

All Lycoming reciprocating aircraft engines unless installed in a rotary-wing aircraft.

TIME OF COMPLIANCE

Half way to recommended TBO or at 1000 hours of operation, whichever occurs first or earlier at owner’s discretion or anytime valve sticking is suspected.

As a product improvement, Lycoming has introduced a new exhaust valve guide material with an increased chrome content for improved wear characteristics. The incorporation of this guide material has significantly reduced the amount of valve guide wear (bell-mouthing) seen by some operators of Lycoming engines.