What was found
JFK/JAL - FLT 037 - ON TAKEOFF FOR FLIGHT JAL 037 OUT OF JFK, NR 3 ENGINE LOST N1 FOLLOWED BY TOTAL POWER FAILURE AND A LOUD BANG AT THE SAME TIME. ACCOMPLISHED EMERGENCY PROCEDURES AND AIR TURN-BACK TO JFK. PERFORMED BORESCOPE INSPECTION, FOUND NO DEFECTS. ATTEMPTED TO PERFORM ENGINE RUN, BUT N1 WOULD NOT ROTATE. REPLACED NR 3 ENGINE AND PERFORMED ENGINE RUN, OPS CHECK PER MM CHAPTER 71-00-00. (X)