What was found
ON SHORT FINAL, CREW EXTENDED GEAR AND NOTICED GEAR UNSAFE LIGHT. THEY ALSO NOTICED LOW HYDRAULIC PRESSURE. ACFT WAS CONFIGURED FOR LANDING AND HAD 20 DEGREE FLAPS. CREW ACTIVATED AUX HYD PUMP AND GEAR WENT DOWN AND LOCKED. CREW WAS ABLE TO TAXI AND USE WHEEL BRAKES WITH AUX PUMP. POST FLIGHT INSP REVEALED A CRACKED JAM NUT ON THE LT MAIN GEAR ACTUATOR HYDR SWIVEL FITTING ALLOWING A RELEASE OF HYDRAULIC FLUID. THE JAM NUT WAS REPLACED AND THE HYDR SYS WAS SERVICED AND TESTED. NO FURTHER DAMAGE WAS FOUND. ACFT WAS RETURNED TO SERVICE.