What was found
FLIGHT CREW DISCOVERED, DURING PREFLIGHT INSPECTION THAT THE RT ENGINE FAN DISK SPINNER ATTACH BOLT, PN 31B0162-01 HAD COME LOOSE FROM THE TIE ROD. RECORDS SEARCH REVEALED THAT THE FAN DISK HAD NOT BEEN REMOVED SINCE NEW. MX REPLACED BOLT AND LOCK WASHER WITH NEW BUD DID NOT FIND ANY OBVIOUS DEFORMATIONS ON OLD PARTS, PILOTS HAD NOT COMPLAINED ABOUT ANY EXCESSIVE VIBRATION OR OTHER ABNORMALITIES PRIOR TO THIS EVENT.