What was found
AIRCRAFT RETURNED OF FLIGHT AS A CONSEQUENCE OF -L & R LANDING GEAR- LIGHTS REMAINED ON WITH MAIN LANDING GEAR LEVER IN UP POSITION. PROXIMITY SWITCH COMPUTER AND D1-25 AND D1-26 SENSORS WERE TESTED AND CHECKED IAW MM 32-60-04 AND MM 32-31-04, RESPECTIVELY, BEING CORRECT. AIRCRAFT LANDED WITH 55418 POUNDS OF FUEL, SO IT WAS NOT NECESSARY THE OVERWEIGHT INSPECTION DUE THAT THE MAXIMUM LANDING WEIGHT IS 58060 IAW DISPATCH MANUAL 5-3-1/2. DURING EXTERNAL REVIEW WERE DETECTED THE MAIN LANDING GEAR LOCKS INSTALLED. INSTALLED DURING MAINTENANCE ACTIVITIES AT HANGAR. LOCKS WERE REMOVED IMMEDIATELY AND AIRCRAFT WAS DISPATCHED.