A dhc-8-100 number 2 hydraulic iso vlv caution light illuminated with 0.7 qts remaining during climb...

Narrative:

Approximately 15 minutes after takeoff [while] we were climbing out of 9;000 ft when the number 2 hydraulic 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 hydraulic 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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1150546
Time
Date	201402
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Dawn
Aircraft 1
Make Model Name	Dash 8-100
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Hydraulic System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

A dhc-8-100 number 2 hydraulic 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.