Dash 8-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; Flight Crew Inflight Shutdown; Flight Crew Landed As Precaution
Aircraft
[We] departed the gate on time and we proceeded to de-ice as the ATIS was calling for light freezing rain on the field. No abnormalities appeared or were detected while deicing and we taxied to [the] runway for departure. Upon reaching [the] runway we completed the Daily Systems Checks and the Before Takeoff Checklist; neither of which led us to detect anything abnormal. Once cleared for takeoff we lined up and I took full control of the airplane for the departure. As I pushed the power levers up to NTOP I noticed and believe called out 'A little lag in the number 2.' This was probably the first indication of any problem however it quickly settled with the #1 and we continued the takeoff. We climbed out; passing 1;000 feet we configured the plane for climb. At this time there was no indication of any issue. As we passed about 5;500 feet I noticed that the power to both engines needed to be advanced (as normal in a climb and temperature inversion) but the #2 was substantially lower than the number 1 (approximately TQ#1 86%/TQ#2 78%). I pushed both power levers forward and the #1 TQ advanced normally to about 98%; however the #2 did not move at all. I verbalized this and then proceeded to 'Split' the power levers; advancing the #2 approximately 3 inches further than the #1. At this point the #2 TQ began to advanced; however; it was very slow and for a few seconds after I stopped advancing the Power Lever; it still was advancing. With the power split; the #2 TQ increased; slowly; to about 103%. I did not want it this high [so] pulled the #2 Power Lever back to match the #1 Power Lever (effectively removing the 'split'). With the Power Levers now not 'split' the #2 remained at 103%. At this time I informed the First Officer that I would like to stop the climb and descend back to 6;000 feet to remain in VMC and top of the ice. We informed the departure controller we were having an issue that may require us to return to the field but we would like to sort it out first and would like vectors to do so. Over the next 2 minutes we proceeded to move the Power Levers forward and back. The #2 was always lagging; always split by about 3 inches and appeared to be getting worse. It was at this time we informed the controller that we would like to return to the field; however; we would need a little bit to accomplish checklist and make a decision if we were going to shut it down. Following the decision to return to field; I contacted the flight attendant via the Call button to inform her. From speaking after the event to the flight attendant it was determined that our conversation went something like this: PIC: We are having issues with the #2 engine and that we will be returning to the field. That I anticipated a normal landing that would result in us taxing off the runway and sorting out more of the situation. We should be on the ground in 10 minutes and I will inform the passengers. FA: Acknowledged.Following speaking to the FA; I informed the passengers of our situation over the PA. Though I was the pilot flying; the FO had his hands full as he was speaking with ATC and working on getting a checklist out for the possible shut down. I determined that it was more beneficial to keep the passengers calm for me to make the announcement and beneficial to allow the FO to speak with ATC. PIC to Passengers: That we were experiencing and abnormality in the right hand engine. At this time we will be returning to the field. We are anticipating a normal landing in which we taxi to the gate following. However; there is a possibility that we need to shut the engine down; if this occurs; understand that it was us that elected to do this for safety of flight and that it changes nothing in our plan for a normal taxi. We do have a few checklists to accomplish but we should have you on the ground in the next 10 minutes.After the announcement the FA proceeded to walk through the cabin and ensure the passenger were calm and answered questions for them. During the time it took to speak to the FA and the Passengers the #2 TQ had slowly rolled back to approximately 20%. The FO and I discussed our options of shutting it down or leaving it running. It was determined that it was now adversely affecting flight characteristics and being unpredictable; it would be safer to shut it down. We begin the engine failure/fire checklist and continued with the shutdown and cleanup procedures. Both pilots remained very calm (which I remember specifically because it was a lot calmer than I would have thought in an event like this); but we annunciated clearly and we verbally reminded each other to take our time on multiple occasions. This allowed for a very 'in control' feeling that I believe contributed to a very successful shutdown. The shutdown occurred uneventfully; however; when we initially pulled the #2 into feather; the plane developed a rhythmic pulsing; which I had never felt in the sim or remember being told about. Because it was unexpected (though I am sure it is normal with the prop in feather in flight) it raised my awareness and brought me a little more out of the 'in control' atmosphere we had developed. Once we selected fuel off and the prop stopped spinning; this pulsing went away. We informed the approach controller that we have shut down the engine and that shortly we will be ready to commence the approach. As we circled over the field; we informed operations that we were a return and requested that they contact [Company] as we felt we were too low to attempt this. I also contacted the FA for a final time to ensure we were on the same page of what the plan would be. She informed me that everyone was doing well and that she was ready to land as well. After clicking off with her; we made a final announcement to the passengers ensuring them that situation was under our control and that we would be landing in just a few minutes. We also stressed the importance of taking commands from the FA to ensure that passengers weren't going take it upon themselves to evacuate. At this time we informed the approach controller that we were ready to come in. He cleared us for the visual and we commenced the approach. We were handed off to tower and were cleared to land. We verified that trucks were standing by at some point with the tower. The crew communication remained very high throughout the approach. I remember asking the FO to remind me in the flare that I would need the opposite rudder than I have been using and to watch my speed throughout the approach. Throughout the entire approach the FO continued to call out 'On speed'; 'a little fast' and kept me informed on the how we were looking on the glide slope. We touched down smoothly and slowly pulled the power back to disc and applied the brakes.  At this time there were no further events that occurred.
DHC-8-200 Captain reported returning to the departure airport after shutting down a malfunctioning engine.