What was found
APU RELIABILITY COLD START ON FLT LEG BWI-PDX FL360-50C. START UNSUCCESSFUL. PERFORMED APU ECU BITE CHK MINI FLAG 1,2,3,48. SUSPECT APU ECU AT FAULT. R/R APU ECU (OFF PART: PN2117342-20, SN B0380) IAW AMM 49-61-05. 3 SUCCESSFUL APU STARTS. OPS CHK GOOD. NO FAULTS FOUND ON NEW ECU, THIS CLEARS DMI 132967. LP;1250872:APU COLD SOAK FAILED 3 ATTEMPTS FL 380 TAT-26. THIS RE-OPENS MDDR 132967, CAT 'C', DUE 26AUG20. LP 1160582: REMOVED AND REPLACED APU ECU UNIT IAW AMM 49-51-25. OPS CHECK GOOD. BITE CHECK GOOD. NO FAULT NOTED.