What was found
(CAN) DURING ROUTINE POST INSPECTION TEST AND WHILE TESTING ENGINE MANUAL MODE ON THE GROUND THE NR 1 ENGINE ENTERED AN OVERSPEED CONDITION FOR 42.40 SECONDS ABOVE 106.5 N2 WITH A PEAK OF 107.852 N2. THIS REQUIRES AN ENGINE "LIGHT" OVERHAUL. THE NR WARNING SYSTEM DID NOT WARN OF A HIGH N2/NR CONDITION TILL THE FINAL 5 SECONDS OF THE TEST. AFTER EXTENSIVE TESTING WITH THE AIRCRAFT MANUFACTURER A CAUSE OF WHY THE WARNING SYSTEM DID NOT ACTIVATE COULD NOT BE DETERMINED TO THIS DATE.