What was found
APU LOW OIL PRESSURE LIGHT LIGHT ON, APU HAD A PROTECTIVE SHUTDOWN APU RUNNING FROM GATE APPROXIMATELY 25 MIN INTO FLIGHT AT FL370 UNCOMMANDED SHUTDOWN T/S, PER B737 FIM TASK 49-70-00-810-807. REPLACED APU ECU, PER AMM TASK 49-61-12-000(400)-801. REPAIR CONFIRMATION SATISFACTORY. NO ACTIVE FAULTS. OPERATIONAL TEST OF APU SATISFACTORY. UPDATE FOR ROTABLE PARTS, ROTABLE PARTS CHANGE WAS INDICATED-TT NR 1088807 SN OFF 8067 UNIT, ELECTRONIC OFF 29-4961-9-0002 8067 ON 29-4961-9-0002 8023.