Date: 201402
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Weather elements / visibility: Turbulence
Aircraft: Dash 8-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
ATC / advisory: Center ZZZ
Aircraft component: Powerplant Lubrication System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Inflight Shutdown; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: On climbout close to our cruise altitude; we encountered some light to moderate turbulence. We noticed a quick flash of the master warning light. Initially we were unable to discern what set it off; but it cycled quickly on and off and we were able to make out that it was Number 1 Engine Oil Pressure light. We immediately looked at the gauge and noticed it bouncing around with the turbulence; fluctuating from approximately 55-62 or 63 PSI. The temperature was noted steady at around 70 degrees; a perfectly normal indication. We began the memory action items; and pulled out the checklist; however; since the pressure was not below 55 PSI; we elected to keep the engine running; as the checklist/action items allow. We called Maintenance on the Sat phone and explained what had occurred. After some discussion about the nature of the indication; normal temperature and no sign of any leak; we all believed it could be an indication issue (bad pressure switch; gauge or associated wiring harness). In cruise; the pressure returned to normal; however the needle did bounce around a bit. As we neared destination and started descending on the arrival; the pressure indication began bouncing around again and then fell below 55 PSI. We ran the immediate action items and the Emergency Checklist. An emergency was declared and we promptly received direct to the field. Since the pressure wasn't below 40 PSI; we kept the engine in feather per the checklist. A couple of minutes after this; the pressure dropped below 40 PSI and we revisited the Number 1 Engine Oil Pressure Checklist to address that issue; which ultimately led to shutting the engine down; which we performed per the checklist. During the whole incident; the oil temperature remained normal and steady at around 70 degrees C. The Flight Attendant was notified of the situation; as well as an announcement made to the passengers. The Number 1 Engine Oil Pressure Checklist led us to the Single Engine Landing Checklist; which was performed accordingly. A normal; single engine; visual approach and landing was performed with equipment standing by. Once clear of the runway; PIC emergency authority was used to single engine taxi to the gate; with ARFF following; where we parked without further incident. Maintenance met the aircraft and found the Number 1 Engine 2 quarts low on oil. This didn't stand out to me as being that unusual; as we see service checks logged that add 1-2 quarts regularly. There were no visible signs of a leak according the Maintenance personnel that met us. We left the aircraft shortly after and do not know the official cause; but at the time they seemed to think it could have been a bad switch; gauge or air in the line. Out of an abundance of caution and following SOP; we feel we still made the right decision to shut down the engine.


Second narrative: [Narrative #2 contained no additional information.]


Synopsis: DHC8-200 flight crew experiences an intermittent engine oil pressure light while flying in turbulence. Oil pressure remains above minimums until descent is initiated and pressure begins dropping. The engine is eventually shut down and a single landing ensues.