As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE IN CABIN AND COCKPIT. RTB - SMOKE DISSIPATED ON LANDING FOUND APU INLET CONTAMINATED WITH ENG OIL 042620, PERFORMED OP 5088. FOUND APU OIL CAP SEAL WORN. REPLACED SAME. RAN APU LEAKS NOTED. PERFORMED OP 5089. PNEUMATIC SYS DUCT BURN.