What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANT REPORTED THAT AFTER TOP OF DECENT THERE IS A BURNING CHEMICAL SMELL IN THE CABIN STRONGEST BY THE 2 DOOR. ODOR WENT AWAY THEN RETURNED ON LANDING. MAINTENANCE REPLACED THE APU GEARBOX VENT TUBE DUE TO COKING, REPLACED THE AIR/OIL SEPERATOR CARBON SEAL (AALA202405261577) AND THE APU OIL COOLING FAN SHAFT O-RING (AALA202405267254). A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED.