What was found
(CAN) ACFT WAS CLIMBING THROUGH FL240 WHEN THE CREW STOPPED THE CLIMB AT FL250 REPORTING A HYDRAULIC FAILURE AND DECIDED TO RETURN TO DEPARTURE AIRPORT. THE CREW SUBSEQUENTLY REPORTED THEY HAD A HIGH TEMPERATURE ON THE HYDRAULIC NR 1 SYS AND THEREFORE NEEDED TO SHUT THE ENGINE DOWN. THE ACFT LANDED SAFETY. MAINTENANCE FOUND A FAILED HYD SYS NR 1 TEMP SENSOR AND REPLACED IT.