What was found
APU INFLIGHT START, THREE ATTEMPTS, FL 400, OAT-52, FL 400, -53,FL 400, OAT -53 ALL ATTEMPTS UNSUCCESSFULL, 49-88 APU FAULT, AUTO SHUTDOWN. PERFORMED BITE TEST OF APU ECU, TEST OK IAW AMM 49-00-00-740-801-A. APU STARTED NORMAL ON GROUND IAW AMM 49-00-00.