What was found
MIA - FLT 432 - ON PREFLIGHT, FOUND NR 4 ENGINE REVERSER DAMAGED. TROUBLESHOT AND FOUND THAT THE LOWER REVERSER TRACK FORWARD YOKE ASSY SEPARATED FROM ENGINE CASE. THIS CAUSED DAMAGE TO BOTH LEFT AND RIGHT AFT FAN AIR DUCTS, TAIL PIPE, RIGHT AND LEFT FIRE WALL SEAL AND BOTH LEFT AND RIGHT AFT COWLING. ENGINE WAS REMOVED AND ROUTED TO SHOP FOR REPAIR. MAIN CAUSE OF ALL DAMAGE WAS FAILURE OF THE LOWER TRACK FORWARD YOKE ASSY. ENGINE WAS RETURNED FROM SHOP. LOWER TRACK FORWARD YOUKE ASSY REPLACED, SYSTEM OPS NORMAL IAW MM 78-30-00. (M)