When I fly the 208B, being free flight or career, and lower the throttle past 30-25 %, the propellor speed races into red. Is this normal, or a bug? Setting condition lever to low idle doesn´t seem to help the case.
What phase of flight are you seeing this in? What’s the prop RPM / prop level position?
Moved to User Support Hub Aircraft & Systems that i smore appropriate for community support.
If I take off or just load in so that I’m in the air and lower throttle, rpm goes wild. I have the propellor at max. Lowering prop lever doesn’t seem to help.
Typically speaking, you’ll want the RPM to be lower than the torque (power) setting when in cruise. Here’s a screenshot from the 208 POH which shows you the RPM and Torque settings to achieve given speeds at given altitudes/temps.
So what you’ll want to do is look at the RPM and the Torque gauges on the left-side of the middle display and match the figures in the chart, so for example:
Set RPM to 1750, then pull the Torque back to 1800 - this would be a middle-of-the-road cruise when it’s 20C outside. The figures change a bit as the temperature changes, so it will largely depend where you’re flying, but the variation isn’t that much so you can use those figures as a general guide and then adjust as needed for your mission (speed, fuel burn, etc.)
Edit to add: To answer your initial question, this is not a bug - I’ve flown the 208 on a bunch of career missions so far, and if I follow the POH I’m able to match that performance almost exactly.
Happens to me too - it seems as if the air spins the prop.
Try descending at idle throttle and you will experience the issue.
It doesn’t seem to happen when I’m on the ground and the engine is running, only in the air.
Here’s a clip of it. I use the HC Bravo Throttle quad. I disconnected it to check if there was some bad controller mapping, but the same happens.
Thanks for trying to figure this out for me, TheRampantGoat 
Yes, this is why there is a ‘Feather’ option on the RPM lever - if you want to descend without the air spinning the prop too much, set it to Feather and the blades will change their angle so they are essentially parallel with the aircraft, not spinning freely in the air. Otherwise, the air will spin the blades.
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Yeah so in that video you’re going way too low on the Power lever all the way into the BETA range (you can see it in the cockpit, but not in the external view with those simplified instruments). This means you have reduced power below the “IDLE” position on the lever.
Normally the prop blade angle is controlled by something called the propellor governor which changes the blades angle of attack to match the RPM you set with the RPM lever. However, in the BETA range, the power lever controls the angle of the blades.
BETA mode is only meant to be used on the ground for taxiing or reverse thrust.
Relevant section from the POH:
And this is a helpful diagram showing the blade angles in different modes (these angles aren’t going to be exact for the 208, this is just an example):
So on the ground this isn’t an issue because the plane isn’t moving through the air at 100kts+ but since you’re in the air, that air pushing against you is also going to be forcing the blades to spin and you don’t have the propellor governor changing the angle of the blades to maintain the RPM so it just goes nuts.
Hope that helps!
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After flying the Caravan more, I think it’s just so different from the 2020 version. Now this machine is not as forgiving. Pulling back the throttle at high speeds (above 80 knots) is not how it was designed I guess, given this is a more study level aircraft.
I’m pretty sure this is a bug though. I un-mapped the binding to allow my throttle to go into beta to make sure it wasn’t getting there. The same is happening to me. I don’t think it is just the prop windmilling faster once the throttle goes below 30% or so.
To test it, i would cut the throttle while flying level and then pitch up to bleed off speed. The prop winds out the whole time with the throttle at idle as if its under power. Further, a full power steep dive with the prop set to max shows a prop rpm of 1975. But a shallow glide to land will wind out the prop to 2465 rpm as soon as the throttle goes below 20-30%. When its winding out, the aircraft doesn’t act is if it has full throttle but it’s definitely not low power or idle power. Makes it very hard to land properly.
Something seems way off with this one.
Feathering does work but you shouldn’t have to feather to land.
Yeah, that makes sense. The Kodiak doesn’t have this problem, if they are comparable when it comes to their engines.
I have tested descending with throttle in flight idle and in beta range. Can reproduce behaviour as described - prop does not spin up in flight idle and does spin up in beta range.
Solution is to not lower the throttle all the way into beta range when descending.
Beta range has nothing to do with my issue. When I pull back my throttle all the way, it stops at idle. Which is when my prop speed goes crazy. I never get to Beta.
I have two screenshots of my caravan descending at 1,000fpm.
Here the throttle is in flight idle, with my physical throttle being slightly above its max bottom position:
The propeller is not spinning out.
Here the throttle is at the bottom of my physical throttle range, with the virtual throttle getting into the beta range:
The propeller can be clearly seen spinning out.
This is completely consistent with what TheRamphantGoat explained from what I can see.
What are you experiencing that is different?