What was found
APU APUC DETECTED FAULT THAT WOULD CAUSE AUTOMATIC SHUTDOWN OF APU IN UNATTENDED MODE OPS, OR COMPLETE LOSS OF APUC BUSS ACTIVITY (BOTH L & R 629) FOR 3 SECONDS AFTER APU MASTER CONTROL SWITCH HAS BEEN IN THE ON POSITION FOR TEN SECONDS. STATUS MSG01- NOT ACTIVE TAXI OUT INTERMITTENT; APU CONTROLLER (APUC) HAS NO OUTPUT ON ANY BUSS. MSG02- NOT ACTIVE TAXI OUT MODE DEPENDENT; APU CONTROLLER (APUC) FLOW SENSING SYSTEM INDICATES LOW FLOW, CAUSED AUTO SHUTDOWN. DB- APU CONTROLLER (APUC) MSG-4918801 INACTV TA INTER MSG-4911110 INACTV TA MODE. ACCOMPLISHED OPS CHECK AFTER INBOUND CAPT STATED APU NORMAL AFTER TWO STARTUPS, NO MESSAGES. REPLACED SURGE CONTROL VALVE. APU OP CHECKS GOOD.