As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. AUXILIARY POWER UNIT FAILED INFLIGHT AFTER APPROXIMATELY 4 HOURS AT 36000 FEET. APU WOULD NOT RESTART. FOUND APU INLET DOOR AND DOOR ACTUATOR ROD END FITTING MISSING. INSTALLED APU INLET DOOR PER AMM 49-15-05 (AALA201710099042) AND APU DOOR ACTUATOR ASSEMBLY PER AMM 49-15-06. OPERATIONAL CHECK GOOD. REFERENCE AALA20171004014