What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO SMOKE ODOR IN PASSENGERS CABIN. A HYDRAULIC LEAK WAS DETECTED IN THE APU INLET DUCT. THE HYDRAULIC LEAK WAS REPAIRED AND WATER SEPARATORS WERE REPLACED IAW MM 21-20-02, TESTED CORRECT. DURING BOARDING, THE HYDRAULIC ODOR WAS PRESENT AGAIN AND FLIGHT WAS CANCELLED. DURING OVERNIGHT CHECK, THE AFT ACCESSORIES COMPARTMENT WAS CHECKED DETECTING A HYDRAULIC LEAK IN THE RETURN LINE OF THE LT HYDRAULIC SYSTEM. HYDRAULIC RETURN LINE WAS REPLACED IAW MM 20-10-03 TESTED CORRECT. DURING OVERNIGHT CHECK, A NEW HYDRAULIC LEAK WAS DETECTED IN THE STEERING HYDRAULIC LINE. THE STEERING HYDRAULIC LINE, APU AND TEMPERATURE CONTROL VALVE WERE REPLACED IAW MM 20-10-03, 49-00-01 AND 21-20-03, TE