Engine failure in a SE with variable pitch: how do you use the blue lever ?

You can feather it, but probably not un-feather it unless you have a so called “un-feathering accumulator”. Most don’t. So it’s a one time deal.

If I recall correctly, in at least some types, you can’t control the governor soon after engine has failed. I think in the arrow the procedure used to be full forward to get least drag, in maybe 30s following engine failure (might be completely wrong).
I’m sure there’ll be more enlightened answers about that.

To lose height / speed, steep banked turns and looking through the side window (side slip)?

On another note, I’ve also wondered from what altitude would it be worth try to stop the propeller (get into a low speed, possibly stalling), as once stopped there is a decent chance it doesn’t restart at best glide. But I think that’s nice in theory, but in an emergency situation if you try to improvise this sort of stuff you might create much more harm. And it’s something I haven’t been convinced is worth practising either :)

Does the POH / AFM says nothing about it?

On the TB20, going full-coarse pitch extends the glide range about 30%.

It’s quite impressive.

Whether I would remember to do it in the event of an engine failure is a good Q. Probably not

I would not use it to introduce drag, because it needs constant oil pressure to work. A better way to get more drag is the flaps, the landing gear, and doing S-turns is very effective.

Side slip is far more precise and flexible than early flap or gear at losing height.

That’s one of those questions where one single answer is not enough… The only fact: Every aeroplane glides better with the engine stopped.

Everybody knows how much force/power it takes to turn a propeller by hand. That power is drained from the potential energy of a gliding aircraft when the engine is windmilling – 1500 times per minute! Once the propeller is stopped it does not make much difference (at least at typical gliding speed) if it is in fine or coarse pitch. With some engines it is necessary to pull back the blue lever fully into coarse pitch (or dedicated feather position where available) to get the rotation stopped. Just slowing down enough to stop the windmilling as with some fixed pitch propellers may not work.
But, as already written above, some propellers can’t easily be unfeathered once in the feather position. So if one wants to keep the option of attempting a restart it might be better not to feather the prop or otherwise entirely stop the rotation, but pull the lever back to a position where the engine windmills slowly. Pulling it over 500 times per minute consumes only one third of the available height than 1500 times while still giving the iced carburator a chance to melt.

Operating the prop on a hydraulic governor requires oil pressure though. I had a partial loss of engine oil in a Franklin-powered Minerva once and although I had enough oil pressure indicated to fly back to the (nearest) airfield, I wasn’t able to control any pitch and the prop went to fine pitch. I don’t think in a real loss of engine power would result in sufficient controllability to depend on it. If you have set it on coarse pitch and base an approach on the prop staying that way you might get surprised when it will go into it’s fallback fine pitch position. In my Opinion you should just account for the worse glide ratio of a fine pitch prop.

Different propellers operate differently, you have to know how yours works for pitch change. “Feathering” is unique to twins and PT-6 powered aircraft. But, coarse pitch is available if the engine is turning above a certain RPM, again, based upon design. Even in some twins, the prop cannot be feathered if the engine stops turning before feather is selected. If you want to know, first read you flight manual, and within its limitations, go glide the plane, and smoothly move the prop control to full coarse, being ready to move back to fine of something is not right.

In my Lycoming O-360 powered aircraft, with an MTV-15 prop, the difference between a glide at full fine to a glide at full coarse is about 800 FPM. It glides at 1700 FPM in fine, and 900 FPM in full coarse, all other things being equal. in full coarse pitch, I can shut the engine down completely, and it still windmills, and I can reselect fine as I wish. A normal power off approach for me will be with full coarse pitch selected, and a move back to full fine at landing as convenient. The aerodynamic braking effect is noticeable as I do this. Thus, I can use the propeller for braking.

The Cessna Caravan is similar in this regard. Glide at idle power and fine pitch will have noticeable braking effect. If you select feather, it feels like a firm gentle push from behind, and the descent rate is halved. The PT-6 engine will remain running with the prop stopped or luffing around slowly. This is a procedure in the flight manual.

Pilot_DAR wrote:

Different propellers operate differently, you have to know how yours works for pitch change. “Feathering” is unique to twins and PT-6 powered aircraft.

And maybe some powered gliders with electrically controlled propellers Mine isn’t a powered glider, but in the event of an engine failure from high altitiude, I’d plan on holding the toggle switch in ‘reise’ (cruise) postion until it reached the stop or until the engine stopped turning.