As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU WILL NOT START FAULT LIGHT ILLUMINATED. DURING T/S OF APU FAULT FOUND THE MAGNETIC DRAIN PLUG COVERED WITH MAGNETIC SILVER COLORED PARTICLES. IAW FIM TASK 49 91 81 200 801 APU REPLACEMENT IS REQUIRED. APU CHANGE COMPLETED. NO DEFECTS NOTED.