Service Instruction No. 1129 D

Supersedes Service Instruction No. 1129C

July 23, 2015

MODELS AFFECTED

All Lycoming direct drive engine models

TIME OF COMPLIANCE

During periodic maintenance inspection of the engine and at anytime the alternator or generator belt is installed.

REASON FOR REVISION

Corrected NM torque values in Table 1

If correctly installed, tensioned and checked periodically, the DC alternator or generator drive belt will give very satisfactory service. However, an incorrectly tensioned belt will wear rapidly and can slip and cause a decrease in electrical energy output.