As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED TO START ON FIRST ATTEMPT. BITE TEST SHOWED LOW OIL PRESSURE FAULT. FOUND DIFFERENTIAL PRESSURE INDICATOR POPPED FOR LUBE FILTER. REPLACED LUBE FILTER PER MM. LEAKED CHECKED OK DPI SHOWED NORMAL AND APU STARTED NORMAL THREE TIMES.