As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH APU RUNNING AND BLEED AIR ON, CABIN AND COCKPIT BEGAN FILLING WITH SMOKE. COMPLIED WITH BOROSCOPE INSPECTION OF THE APU INLET AND FOUND THE INSIDE FAN SEAL LEAKING. REMOVED AND INSTALLED APU IAW MM 49-10-00. AFTER REPLACEMENT OF APU REMOVED WATER SEPERATOR CONLESCER SOCK AND FOUND VERY DIRTY. REMOVED AND REPLACED COALEACER SOCK IAW MM 21-51-00. RAN APU AS REQ. OPS & LEAK CHECKED GOOD. NO ODOR NOTED.