Narrative:

Just after leveling at 17;000 MSL the first officer noticed we were losing hydraulic fluid from the #2 system. Quantity was at approximately 2.5 at this time. We watched the gauge for a few moments hoping it would stabilize but it continued to drop slowly. As we were approximately half way between departure and destination we elected to return to our departure airport. As we continued to fly; the quantity continued to drop until it was at zero approximately 5 minutes before landing. We later learned the main hydraulic line to the engine cracked.the first officer notified ATC and got a clearance back while I called dispatch and maintenance; informing them of the situation. I then notified the flight attendant and informed the passengers of the situation advising them to anticipate a normal landing. We then reviewed the checklists/procedures for a #2 hydraulic iso vlv caution light and alternate landing gear extension. We discussed runway choice and whether or not it would be a problem to taxi to the gate. About 35 miles from an airport when the quantity had dropped to about 0.5 we finally got the #2 hydraulic iso vlv caution light; along with a #2 engine hydraulic pump caution light. We ran the appropriate checklists; declared an emergency; and got vectored for about a 15 mile final to give us time to do the alternate gear extension. Shortly before turning on to final I took control of the aircraft so the first officer could complete the alternate gear extension. We completed our checklists; landed without incident; and taxied to the gate where we inspected the #2 engine cowling with maintenance and found it was bathed in hydraulic fluid.

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Original NASA ASRS Text

Title: A Dash-8-300 flight crew declared an emergency and returned to their departure airport when the #2 hydraulic system failed.

Narrative: Just after leveling at 17;000 MSL the First Officer noticed we were losing hydraulic fluid from the #2 system. Quantity was at approximately 2.5 at this time. We watched the gauge for a few moments hoping it would stabilize but it continued to drop slowly. As we were approximately half way between departure and destination we elected to return to our departure airport. As we continued to fly; the quantity continued to drop until it was at zero approximately 5 minutes before landing. We later learned the main hydraulic line to the engine cracked.The First Officer notified ATC and got a clearance back while I called Dispatch and Maintenance; informing them of the situation. I then notified the Flight Attendant and informed the passengers of the situation advising them to anticipate a normal landing. We then reviewed the checklists/procedures for a #2 HYD ISO VLV caution light and alternate landing gear extension. We discussed runway choice and whether or not it would be a problem to taxi to the gate. About 35 miles from an airport when the quantity had dropped to about 0.5 we finally got the #2 HYD ISO VLV caution light; along with a #2 ENG HYD PUMP caution light. We ran the appropriate checklists; declared an emergency; and got vectored for about a 15 mile final to give us time to do the alternate gear extension. Shortly before turning on to final I took control of the aircraft so the First Officer could complete the alternate gear extension. We completed our checklists; landed without incident; and taxied to the gate where we inspected the #2 engine cowling with maintenance and found it was bathed in hydraulic fluid.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.