Dash 8-300
Flight Crew Air Transport Pilot (ATP)
Distraction; Time Pressure; Training / Qualification; Workload
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
We experienced a complete loss of the #2 hydraulic system quantity in cruise flight. This occurred at FL190 shortly after leveling. We observed the master caution light illuminate; and an associated #2 ENG HYD PUMP caution light was illuminated. I looked at the hydraulic gauges and noticed zero #2 hydraulic pressure; and zero #2 hydraulic quantity. Shortly thereafter; the #2 RUD HYD; RUD PRESS; and RUD FULL PRESS caution lights also illuminated. I instructed the pilot flying to remain below 200 KIAS. I then ran the #2 HYDRAULIC SYSTEM FAILURE CHECKLIST with a quantity of zero. I then contacted my Dispatcher; and we agreed to return to the departure airport. I declared an emergency with ATC; and we received our new clearance to return to the departure airport. At this time; I spoke to the Flight Attendant and informed her of our condition; and that we'd be returning to the departure airport. I told her it would be normal landing; but the Airfield Rescue and Fire Fighters (ARFF) vehicles would be escorting our plane to the gate. I made a PA to the passengers. After all communications were complete; the First Officer transferred the flight controls to me so he could review the ALTERNATE LANDING GEAR EXTENSION checklist that he would be performing. I remained pilot flying for the remainder of the flight. We landed uneventfully. Once clear of the runway; we terminated the Emergency condition with ATC. The ARFF vehicles followed us to the gate; found no hazards after engine shutdown; and I told them they could clear. Maintenance informed me there was a blown o-ring on a hydraulic line.
An 'O' ring on a DHC8-300's Number Two Hydraulic system failed in flight causing the loss of all hydraulic fluid and system pressure so an emergency was declared and the flight returned to the departure airport.