Service Bulletin No. 621 B

October 5, 2015

MODELS AFFECTED

IO-320, -360, -390, -540, -580; AEIO-320, -360, -390, -540; LIO-320-B1A; O-320-B2D, -D1D; (L)O-360-A1H6, -A1N6, -A1G6D; HIO-360; LIO-360; O-360-A1H, -A2G, -A4G, -A4J, -A4K, -A1G6, -C1F, -C4F; O-540-L3C5D; and TO-360-C1A6D

TIME OF COMPLIANCE

50 hours from the issue date of this Service Bulletin or the next regularly scheduled maintenance event (whichever occurs first)

REASON FOR REVISION

Added new affected engine models.

This Service Bulletin is notification of a requirement to replace specific diaphragm-type fuel pumps identified herein as a corrective action in response to a confirmed non-conforming fuel pump in the field. Continued operation of a non-conforming fuel pump can cause fuel leakage out of the airframer’s vent line or into the engine crankcase.