What was found
APU FAULT AND AUTO SHUTDOWN, APU FAULT ON ECU GEN FILTER. FOLLOWED FIM TASK 49-11, FAULT TREE 969. FOUND SCAVENGE FILTER ELEMENT BAD. R & R IAW AMM 49-29-03-004 001. OPS CHECKED GOOD. INSPECTED MAGNETIC CHIP DETECTOR, NO METAL FOUND IAW 49-27-04-206-0014. R & R THE LOW OIL PRESSURE S/W AND ECU. NO HELP. ORIGINAL ECU REINSTALLED. REMOVED AND REPLACED APU SURGE VALVE, OPS CHECKED IAW 49-53-01, OPS CHECKED GOOD.