As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH THE RT ENG GEN ON MCO AND THE APU RUNNING IN FLIGHT, THE CREW GOT AN APU LOW OIL QTY MESSAGE. LATER THE APU SHUT DOWN AND THE A/C WAS DOWN TO A SINGLE ELECTRICAL SOURCE. IDG REPLACEMENT AND APU T/S IN WORK OPEN COWLING SERVICED APU. RAN APU. FOUND OIL FITTING WITH A MISSING CAP. REPLACED MISSING CAP. RAN APU. FOUND NO LEAKS.