Props High or Low?

[wt219200]

If you lost an engine in a complex single like the Piper Arrow or even just training sim-engine out would you pull props to low RPM or keep them high? Situation: 3000 AGL. I would go high but a nameless fellow CFI I will call B L argues keep em high. Debate on

I also meant to state the engine restart was unsuccessful lets say fuel starvation. In this case the CFI still argues props high

 

[USMCmech]

High RPM gives you the best chance for a restart.

Low RPM gives you the best glide distance.


Use the aproprite setting for your situation.


For training purposes, you are going to do a go-around sometime soon, so I have my students leave them high.

 

[heph224]

If your engine fails, put the blade at a high RPM and try to restart. Then, if the restart was unsuccesful, set the lever to a low rpm pitch setting to decrease drag and get a better glide distance.

 

[minitour]

I agree with going high pitch/low RPM to get your best glide after you were at low pitch/high RPM to attempt a re-start.

HOWEVER...the complex singles I've flown all use oil pressure to drive the prop into a high pitch/low RPM condition...so if you lose the engine, you MAY not be able to get the prop into that low RPM/high pitch condition.

..just something to think about.

-mini

 

[Sam Snead]

Complex single; I teach; once you've decided not to continue trying to restart;

Leave it high RPM unless you can't make your field. Then pull the prop all the way back.

In a poorly planned or unlucky situation, the "boost" you get from the quasi-feather might just get you up and over the last row of trees.

If you've got the field made, leave the prop where it was.

But, (as minitour pointed out) if you have nil oil pressure, you may not be able to go to low RPM. So hope you have an engine failure without massive oil starvation.

 

[aucfi]

For traning purposes, I would not touch the prop control; just leave it full forward. I do show my studends how much drag the prop creates when in the high rpm setting by pulling it back to the low rpm setting one time.

If it actually occured, Id follow the POH's instructions. The checklist does not call for a change in prop setting following a failed attempt to restore power but the amplified procedures suggest moving it to the full decrease rpm to prolong gliding distance.

"At best gliding angle, with the engine windmilling, and the propeller control in the full 'DECREASE rpm," the aircraft will travel approximately 1.6 miles for each thousand feet of altitude."

Thats from an Arrow 3 POH

 

[troy]

It depends on the terrain below you, here in South Dakota, landing spots are plenty, but in the mountains, pull it back.

 

[Iceman21]

Mini is right, if you have lost oil pressure then the prop (in most piston singles) will revert to HIGH rpm and you are stuck with it there.


Now if you ran out of gas, on the base leg, now were talking.

 

[Dr Pokenhiemer]

Pull the props back and increase your glide. So you think you can make the field? What happens if you run into stronger winds as you get lower and all of sudden you realize you can't make it? You'll wish you would've pulled it back from the getgo.

For training purposes? Train like the real thing. Don't be afraid to show your students how the plane will perform. That's your job!! Train them to handle emergencies!! You are there so they WON'T get out of control. You are there to make sure the prop goes full forward before the go around. Do a simulated engine out on downwind. Teach them to deadstick the landing--they'll have to do it on the checkride.

 

[aucfi]

Pull the props back and increase your glide. So you think you can make the field? What happens if you run into stronger winds as you get lower and all of sudden you realize you can't make it? You'll wish you would've pulled it back from the getgo.

For training purposes? Train like the real thing. Don't be afraid to show your students how the plane will perform. That's your job!! Train them to handle emergencies!! You are there so they WON'T get out of control. You are there to make sure the prop goes full forward before the go around. Do a simulated engine out on downwind. Teach them to deadstick the landing--they'll have to do it on the checkride.

So do all instructors tell their students to pull their prop back during every simulated engine out? I was never taught to do this but was made aware that I could if needed. Would that cause excess wear on the speeder spring? Just curious...

If you train without pulling it back and consistently make the field/runway without any problem, it shouldnt matter whether you pull it back or not if you had an actual failure. Common sense and good judgement (through training) should tell you whether you should have to pull it back if you really needed the extra distance.

Going back to my previous post; the actual checklist does not say pull it back if a restart cannot be made. The amplified procedures simply points out how far you can glide with the prop in the full decrease position. Seems to me Piper left it up to the PIC to make that decision.