Dash 8-100
Flight Crew Air Transport Pilot (ATP)
Training / Qualification; Workload; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; General Declared Emergency; General Maintenance Action
Aircraft
Approximately 15 minutes after takeoff [while] we were climbing out of 9;000 FT when the Number 2 HYD ISO VLV caution light illuminated. At that point we noticed the Number 2 hydraulic quantity was at 0.7 QTS. No other lights illuminated and pressure on the Number 2 system remained normal. We ran the Number 2 HYD ISO VLV Caution Light Checklist and determined we should return to the departure airport. As pilot monitoring; I called Dispatch via the SATCOM and told them of the situation; they also agreed returning to ZZZ was the best course of action. After notifying the Flight Attendant that we were returning to the field (no brace signal); we then declared an emergency with ATC and gave ZZZ Approach souls and fuel on board. The First officer and I switched roles so he could perform the alternate landing gear extension easier from the right seat. We performed the alternate gear extension and landed without incident. After clearing the runway we asked the emergency equipment to verify that we weren't leaking anymore fluid; which they confirmed we were not. We taxied to the gate where Maintenance met us and noticed fluid leaking from the Number 1 nacelle. We shutdown the aircraft and deplaned.It is unclear as of right now as to why the event occurred.
A DHC-8-100 Number 2 HYD ISO VLV caution light illuminated with 0.7 QTS remaining during climb; so the appropriate checklist was completed; an emergency declared and flight returned to the departure airport where fluid was found dripping from the Number 1 engine nacelle.