As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW COMMENTS: DURING TAXI APU SHUT DOWN WITH LOUD GRINDING MECHANICAL NOISE IN AFT GALLEY. SOME OIL SEEPING DOWN A-C IN APU AREA. DID NOT ATTEMPT APU START FOR SAFETY REASONS. ECU BITE SHOWED "REVERSE FLOW". SOME OIL FOUND SEEPING DOWN IN APU AREA. FOUND WIRE ASSEMBLY APU GENERATOR HARNESS BURNED AT GENERATOR TERMINAL. NO METAL NOTED IN CHIP DETECTORS. APU TURBINE FREE WHEELS EASILY.