Date: 201301
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Dash 8-100
Operator: Air Carrier
Operating under: Part 121
Flight phase: Descent
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Hydraulic Fluid
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: During descent from 15;000 to 11;000 in cruise flight the #1 HYD ISO VLV and ROLL SPLR INBD HYD caution lights illuminated. There was a loss of the #1 hydraulic fluid quantity and the rudder isolation valve system operated properly. The crew ran the appropriate non-normal and normal checklists; declared an emergency; communicated with all parties; and landed without further incident or disruption of the flight. About 40 minutes into the flight I noticed the #1 caution light illuminate and I immediately looked at the hydraulic panel. The #1 quantity quickly dropped to .5 quarts; or slightly less. I notified the First Officer of the situation and told him it was a concern. Soon the ROLL SPLR INBD HYD caution light illuminated as well. I disconnected the autopilot briefly to make sure aircraft control was normal and the First Officer pulled out the #1 Hydraulic System Failure Checklist. We scanned the checklist to make sure we were addressing all important items; and then I called the flight attendant. I told him that we had a failure of one of our hydraulic systems with a loss of fluid and asked him to look for any dripping fluid; abnormal smells; or other evidence in the cabin. He said that all appeared normal. I told him we would be declaring an emergency and would get back to him with details when we finished our flight-deck duties. The First Officer and I then thoroughly reviewed the #1 Hydraulic System Failure Checklist; and declared an emergency with Approach. I called Dispatch to relay the situation; and also spoke with Maintenance Control. I called the flight attendant back and gave a thorough briefing of the situation: that there would be no need to brace; that trucks would be standing by; and that we would stop after landing and evaluate the situation before proceeding; etc. I then made a PA to the passengers briefly explaining that we had a mechanical problem that affected one of our two braking systems. I reassured them that there was no need for concern; and alerted them that there would be emergency vehicles standing by on the ground to check the plane. I slowed and configured for the flap less landing; using the Vref/approach; and go-around speeds from the non-normal checklist. The landing was regular/unremarkable; and I did not need to apply reverse thrust or the parking brake. The emergency vehicles observed no abnormalities on the outside of the aircraft. After speaking with operations; I decided to continue taxiing to the terminal. We arranged to stop short of the lead-in line and be towed in the rest of the way. Aircraft control without normal brakes was not an issue in this plane. The engines were rigged such that propeller pitch in the ground-beta mode could completely control speed and stop the aircraft. I slowly taxied to the lead-in line; set the parking brake; turned off the nose-wheel steering; and shut down the engines. The ground crew hooked up the tug and towed the aircraft rest of the way to the gate.




Synopsis: DHC8-100 Captain experiences the loss of the number one hydraulic system due to a leak during initial descent for landing. An emergency was declared and the flight continued to destination for a no-flap landing.