As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER T/O, ALL LAV SMOKE DETECTORS SOUNDED WITH SMOKE AND HAZE REPORTED IN CABIN BY FLIGHT ATTENDANTS. EMERGENCY RETURN TO ATL. FOUND APU INLET CONTAMINATED WITH OIL. OIL LEVEL IN SIGHT GAUGE WAS AT RE-FILL LINE. OIL TANK CAP IS INSTALLED AND SECURE. MX STILL IN PROGRESS 0910/17. FOUND OIL CONTAMINATION IN APU INLET. LK CKD APU. FOUND B-NUT LEAKING ON OIL LINE AFT FILTER MODULE. TIGHTENED SAME. LK C GOOD. REMOVED LOWER DOOR ASSY CLEANED INLET AND DOOR ASSY REPLACED.