Narrative:

We noticed that the hydraulic quantity gauge was lower than usual. All of the hydraulic accumulators were pressurized and in the green and normal. The indication on the gauge was still in the green arc and within limits; but trending towards the yellow. We decided to contact our dispatch and notify them of the potential issue. The captain and I ran through the hydraulic loss checklist; but since our indications were still in the green and we were not losing fluid catastrophically we decided to monitor the gauges. During this time the captain and I transferred controls and I became the pilot flying. The captain told dispatch of the issue and dispatch asked what our intentions were. We decided to head back to our departure airport since we were around 65 miles from there. When the captain finished the call he informed ATC that we needed to return. They asked us if we needed to declare an emergency and we told them 'not at this time.' we made this decision because indications were still within limits. When we were around 20 miles; the gauge had trended into to the yellow arc. We still monitored the gauge. The captain and I discussed landing without flaps in case we lost more fluid after putting the gear down. This also helped with our decision of going where there was plenty of runway. The captain talked to the flight attendant and passengers letting them know we were returning. The indication on the hydraulic quantity was staying in the yellow arc and we still had pressure in all of the accumulators. We were cleared to land and I called for 'gear down.' as the gear was coming down we got a hydraulic cwp and then it quickly extinguished. The gear came down and locked with all green indications. The captain and I decided to land without flaps as we had previously briefed due to the unknown state of our quantity and to avoid any other complication. We landed and slowed down. The captain then said my controls and we cleared off the runway. I asked if he wanted to stop on the runway or clear off. The captain stated that he did have brake pressure and that all the accumulators were still pressurized and we decided to clear the runway and pull into the gate. On further inspection maintenance found a hole in one of the hydraulic lines.

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Original NASA ASRS Text

Title: SF340 flight crew noticed enroute a lower than typical hydraulic quantity; as a precaution they decided to return to their departure airport. While enroute to their diversion; the HYD CWP alerted. A hole in a hydraulic line was later discovered by maintenance to be the cause of the CWP alert.

Narrative: We noticed that the hydraulic quantity gauge was lower than usual. All of the hydraulic accumulators were pressurized and in the green and normal. The indication on the gauge was still in the green arc and within limits; but trending towards the yellow. We decided to contact our Dispatch and notify them of the potential issue. The Captain and I ran through the Hydraulic Loss checklist; but since our indications were still in the green and we were not losing fluid catastrophically we decided to monitor the gauges. During this time the Captain and I transferred controls and I became the pilot flying. The Captain told Dispatch of the issue and Dispatch asked what our intentions were. We decided to head back to our departure airport since we were around 65 miles from there. When the Captain finished the call he informed ATC that we needed to return. They asked us if we needed to declare an emergency and we told them 'not at this time.' We made this decision because indications were still within limits. When we were around 20 miles; the gauge had trended into to the yellow arc. We still monitored the gauge. The Captain and I discussed landing without flaps in case we lost more fluid after putting the gear down. This also helped with our decision of going where there was plenty of runway. The Captain talked to the Flight Attendant and passengers letting them know we were returning. The indication on the hydraulic quantity was staying in the yellow arc and we still had pressure in all of the accumulators. We were cleared to land and I called for 'gear down.' As the gear was coming down we got a HYD CWP and then it quickly extinguished. The gear came down and locked with all green indications. The Captain and I decided to land without flaps as we had previously briefed due to the unknown state of our quantity and to avoid any other complication. We landed and slowed down. The Captain then said my controls and we cleared off the runway. I asked if he wanted to stop on the runway or clear off. The Captain stated that he did have brake pressure and that all the accumulators were still pressurized and we decided to clear the runway and pull into the gate. On further inspection Maintenance found a hole in one of the hydraulic lines.

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.