As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU NO START WITH 3 ATTEMPTS APU FAULT EICAS. REPLACED STARTER REF MM49-41-01 AND ECU REF MM 49-61-05. NO HELP. APU STILL WOULD NOT START. ECU SHOWED NR 1 SPEED SENSOR. REPLACED APU BATTERY AND NR 1 MONOPOLE RUNS FOR APPROX 15 MIN THEN SHUTS DOWN. REPLACED AND INSTALLED GENERATOR FILTER DELTA PRESSURE SWITCH PER MM 49-27-15, APU WAS RUN FOR 1HR, OPS CHECK OK.