What was found
(CAN) ON APPROACH, GEAR SELECTED DOWN, RIGHT MAIN GEAR DID NOT INDICATE DOWN AND LOCKED. ALTERNATE GEAR EXTENSION CARRIED OUT AND RIGHT STILL INDICATED AN UNSAFE CONDITION ON BOTH NORMAL AND ALTERNATE EXTENSIONS. PILOTS DECIDED TO DO A "TOUCH AND GO" TO SEE IF AIRCRAFT WOULD BEAR WEIGHT. DURING TOUCH AND GO, THE GEAR DOWN LIGHT ILLUMINATED. AIRCRAFT DID CIRCUIT AND LANDED SAFELY. INSPECTION FOUND THE STABILIZER STAY ASSIST SPRING BROKEN.