Incident Overview
The flight crew reported that, while in cruise flight, the number 1 hydraulic (utility) fluid quantity dropped below the low red mark on the gauge. In response, the crew switched to the secondary hydraulic system and diverted to a nearby airport, where a landing was made without incident.
Maintenance Findings
After landing, maintenance personnel inspected the aircraft and discovered a hydraulic line to the flap drive motor was chafed through and leaking.
Previous Occurrence
According to the flight crew, this was the second time that day that the number 1 hydraulic system fluid level had dropped. Prior to the last departure, maintenance personnel had serviced the system with hydraulic fluid. On that occasion, the flight crew ran the engines and cycled the flight controls while maintenance personnel looked for leaks. No leaks were found, and the aircraft departed on the next leg of the scheduled flight.