As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUTDOWN AT GATE. NO TIME TO T-S INOP APU, NO MSG PRESENT. IF APU REPLACEMENT IS REQUIRED, PLEASE INSTALL S/N 61811 IF POSSIBLE. -INF- :AUTO SHUTDOWN WITH GEN FILTER ON BITE. -INF- :CHECK DPI AND FILTERS. NO DEFECTS FOUND. CHANGED APU CONTROLLER RAN APU. AFTER 20 MINUTES APU AUTO SHUTDOWN. NEED GEN DELTA P SWITCH (PCN 481-1503). RESET ECB AND OPERATED APU FOR OVER AN HOUR LOADED. CHECKS NORMAL.