As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ACCESSING APU FOR FUEL FILTER CHANGE FOUND OIL FILTER INDICATOR POPPED. ACFT GROUNDED. REMOVED FILTER AND INSPECTED BOWL AND FILTER FOR CONTAMINATION. NONE FOUND. INSTALLED NEW FILTER AND RAN APU OPS AND LEAK CHECK GOOD, REF 49-91-12-400-802.