What was found
HIGH SPEED BUFFET EXPERIENCED BETWEEN 250 AND 290 KTS AT FL160. BUFFET INCREASES WITH SPEED. ALSO, NOTICED LT AILERON SHUTTERING. MAINTENANCE REPLACED LT AILERON TRIM TAB HORN ASSEMBLY AND HARDWARE. A SUCCESSFUL OPS CHECK FLIGHT WAS PERFORMED. ACFT WAS RETURNED TO SERVICE. PARTS REPLACED: AILERON HINGE, PN NAS77-6-009, TRIM TAB BEARING HORN, PN 6324130-12, HINGE BUSHING, PN 6624019-1, ROD BOLTS, PN NAS464P3-8.