What was found
ON APPROACH INTO DTW, LANDING GEAR DOOR OPEN LIGHT REMAINED ON AFTER GEAR WAS EXTENDED, RECYCLED GEAR WITH NO HELP. ACCOMPLISHED EMERGENCY GEAR EXTENSION PROCEDURES. AIRCRAFT LANDED WITHOUT INCIDENT. FOUND RIGHT MAIN GEAR DOOR ROLLER NOT SECURED PROPERLY, TIGHTENED ROLLER ASSEMBLY TO RIGHT MAIN GEAR DOOR. ALSO, REPLACED LEFT MAIN GEAR DOOR DUE TO DAMAGE INCURRED. OPERATIONAL CHECK OK ON GEAR SWING, AIRCRAFT RETURNED TO SERVICE.