Hello fellow Dash8 drivers,

 

Since about a week I'm the proud owner of this fantastic aircraft and I'm gradually getting acquainted with it. Quite a learning curve I must say, if you're used to fly the PMDG 737 or the Airbus Extended. So for the time being I'm doing lots of circuit flying. What I find particularly difficult is managing the airspeed on final approach. Finding the 'sweet spot' wiith the throttle lever on my Logitech Extreme 3D, in order to hold the desired speed of e.g. 127 kts is not easy (to put it mildly) as the speed tends either to increase or decrease. On the other hand, if I select IAS for holding the speed, the aircraft seems to stop following the glideslope. This continuous 'battle' ends in switching off the autopilot alltogether and trying bring the bird back on track manually. The subsequent landing is often not very 'pretty' because of (again) the difficulty of manual speed control. Would any of the experienced users of this aircraft please be so kind as to give some advice on this matter? Am I overlooking something? FYI: I'm approaching with flaps 15, 850 RPM. Thanks in advance for any input.

 

Kind regards,

René

   

If Im not mistaken, condition levers must be full forward. Also watch the speed trend line on the ASI...somehow it helps to track it with the throttle instead of airspeed itself.

You can land the Q400 with the props in 850 but then you'd need to select the mode which automatically sets the props to full should you do a go around. For the purposes of learning (and in the real thing often happens in gusty approaches) set the props to Max when on final approach. Speed control is very tricky in the Q400, especially at flaps 15. Don't aim for a beautiful landing as they're nearly impossible to get with those long main gears and hard struts. At flaps 15 at a sensible weight you should need around 20% torque to keep it within the Vref speed range and don't worry about carrying a little extra speed as the Q400 stops quickly. Getting slow is more of a problem and it's easy to bang the tail if you get it wrong. One final thing is keep the power on through the flare until the nose gear is down - the worst thing you can do on a Q400 is chop the power at 15-30 feet as you would in a jet. It will fall out of the sky and HURT! 

Renee,

 

Welcome to the Q400 world.  I could elaborate on flying the approach in the Dash but this topic has been discussed at length in both this forum and our Official Majestic Forum (a search should reveal some good reading material).  Anyway, with that said, to keep it short and simple, unlike the jets where you can set manage your speed via the FMC or MCP, the Dash requires that you pay close attention to the airspeed, and occasional minor adjustments need to be made, especially during the approach to ensure that you do not get too slow or too fast (attempt to make it a habit of either writing on a piece of paper or inputting your approach speeds into the PFD) thus giving a visual cue for your refs.

 

There are some good video illustrations on YouTube to help is seeing how this is performed.

 

Best regards

Yesterday, on the tutorial flight from CYZD to KEWR the following happened: established on final ILS Ryw 22L I became to slow and received the stall warning. I immediately disconnected the autopilot. The autopilot warning sound was there but still it was impossible to steer by hand. The elevator was frozen until I repeatedly switched the autopilot on and off.

 

Can someone comment?

 

Michael

Thanks for the replies. More study and practice...

 

@Michael: I'm afraid I can't help you; maybe someone else will chime in.

 

Kind regards,

Rene

in order to hold the desired speed of e.g. 127 kts is not easy (to put it mildly) as the speed tends either to increase or decrease. On the other hand, if I select IAS for holding the speed, the aircraft seems to stop following the glideslope. This continuous 'battle' ends in switching off the autopilot alltogether and trying bring the bird back on track manually.

IAS is a vertical mode (i.e. it controls speed by manipulating pitch, it cannot adjust thrust), so engaging IAS hold will disconnect the APP G/S mode. During approach you must manage the speed yourself by manipulating the thrust levers.

 

During approach, try not to place the power levers at the bottom of the in-flight range, at low power settings the propellers effectively act as brakes, which could be why you are struggling to maintain a steady airspeed. Try and keep a little positive torque at all times during the approach and do not reduce power during the flare (this reduces prop wash over the wing and causes a big reduction in lift, so you drop like a stone).

 

Everything else you are doing sounds okay, Flap 15 is definitely easier to handle than Flap 35. You could try a Reduced NP Landing (set condition levers to 850 rpm, press RDC NP LDG, then set condition levers full forward) and see if that makes it easier for you.

Thanks very much Chris!

 

Kind regards,

René

...I became to slow and received the stall warning. I immediately disconnected the autopilot. The autopilot warning sound was there but still it was impossible to steer by hand. The elevator was frozen until I repeatedly switched the autopilot on and off.

Sounds like you could have been out of trim so you didn't have sufficient elevator authority, it's important to keep on top of the trim during approach and landing. Or it could have been the operation of the stick pusher, if you failed to react to the stick shaker quickly enough. The only other thing I can think of is a deep stall, but the stick pusher is there to prevent that. I suppose it could be a bug but I've not heard anyone mention anything similar.

The short answer: Very carefully! As you would with any DHC airplane: Wings and flaps that produce more than sufficient lift, notorious for being STOL airplanes (hence the wings and the flaps) as well as having large tails, which by itself is advantageous but needs to be properly managed, especially when it's windy.

 

Long answer: Stablise the approach early enough, that is get gear, flaps and all your proper landing checks in advance, so you can concentrate on flying the plane. "Speed is the key" with any airplane, but even more with this kind of turboprops. On final approach (say the last 1000ft or so) you should basically replace the artificial horizon with the airspeed indicator in your instrument scan. Constant scanning (and control!) of the airspeed is critical to a successful landing. So if landing from an instrument approach you should be doing something like: speed, flight director, speed, glide slope, speed, localizer, speed. Once you're flying visual, it becomes a game of two: Speed and out the window, then back to speed, and so on. Proper scanning leads to proper power lever movements. 

 

Also, as others have pointed out, there's no autothrottle on a turboprop (not those I know anyway!), so the IAS mode on a turboprop is (since you're familiar with PMDG) the equivalent to the LVL CHG mode on a B737. It will only maintain speed with pitch. Please note that I said "maintain" and not "control". Enjoy the beauty of turboprops: real flying my friend! You'll love it once you get the hang of it.

The only thing I will add is that when you're landing with flaps 15, you'll notice you'll have to re-add power as your pitching up to about 3º when stabilized on the approach- flaps 15 approaches are very slightly "nose up." As the autopilot should be in APPCH mode, it will pitch to hold the glideslope as the airplane slows- make sure when this happens you support your target speed with some power, as some above have suggested, about 20% TQ.