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Engine failure checklist with CS prop

bobmarkert

Well Known Member
I was helping a friend review his emergency checklists and a question came up regarding his ENGINE FAILURE IN FLIGHT checklist.

IO360
Constant Speed RV200 Whirlwind prop (non-aerobatic/no counterweights)

If the engine quits and has stopped turning I believe it doesn?t matter where you put the prop control

If the engine quits but is still wind milling, does it matter where you put the prop control ie full fwd or full aft?

I?ll grab a beer and will be right back??.

Thank you
 
Pulling the prop control all the way back will result in maximum pitch and minimum drag (If the governor is operating, i.e. prop is windmilling)

Actually if the engine stops turning, drag is reduced even further.
 
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I have seen taught:

If the prop is still tuning, and restart is unsuccessful, pull the prop back to course pitch to minimize drag.

Min sink speed (slower than best glide) may also be considered while trouble shooting, making radio calls, looking for emergency field.

If distance is required use best glide taking into effect wind aloft direction.
 
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What flying said. Must have oil pressure or a full feathering prop. Otherwise the spring in the hub sends the blades to flat pitch, same as on shut down. There may be some residual oil pressure on the engine but not enough to counteract spring pressure to drive the prop to coarse pitch. ?Maintain thy airspeed lest the earth rise up and smite thee mightily?.
 
Peter Garrison, a frequent contributor to Flying magazine, wrote an excellent article on this topic. It was so good that even a numbskull like me could remember its lessons.

With a Constant Speed prop, go FULL COARSE to reduce equivalent flat plate drag area.
Throttle should be FULL OPEN to reduce pumping losses across the throttle butterfly.

Excellent points made above considering minimum sink vs maximum glide speed. They can be quite different. If over inhospitable lands where there isn't a better spot to land, minimum sink gives you more time to think, prepare, communicate, get a re-start, etc.
 
Also if IFR, it's good to keep track of the bases you are descending through. You should make sure you have extra airspeed available so that when you come out you will have some maneuverability to avoid ponds. trees, buildings etc.

Coming out of the clouds with out any extra airspeed really limits your options to whatever is in front of you when you break out.
 
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Also depends on the type of governor if a windmilling Prop will go coarse.
On my 0 320 with a Hartzell Prop it will go coarse with an MT governor but not with a Hartzell governor. Going coarse significantly improves glide performance.
YMMV

Fin
9A Australia.
 
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grabbing another beer

Thanks for the replies.
To summarize:

If the engine is wind milling there may or may not be a chance to get the prop to course pitch but if I want a simple procedure that I can take from plane to plane it would be:

If unable to restart (Wind milling or not)
-Throttle FULL OPEN
(pumping resistance countermeasure)

- Propeller Control FULL AFT (OUT)
(depending on your planes configuration lever or slider)

‘Gunna grab another beer

Thanks
Bob
 
Try it...

If you really want to see what a difference it can make by pulling the prop lever all the way back, try it sometime while on final approach with the power pulled back. You will be surprised at the instant acceleration from the loss of drag. It is especially noticeable with a 3-bladed propeller.

I know someone who had an engine quit at 12,500? due to running a tank dry. They never selected the other tank, but nonetheless the airplane was destroyed when it landed in a field 2 miles short of a runway. The prop lever was pushed to the full forward position and remained there for the entire descent, and it had a 3-bladed prop. Most likely they would have made the runway if the prop lever had been pulled completely aft.

Vic
 
If you really want to see what a difference it can make by pulling the prop lever all the way back, try it sometime while on final approach with the power pulled back. You will be surprised at the instant acceleration from the loss of drag. It is especially noticeable with a 3-bladed propeller.

I know someone who had an engine quit at 12,500? due to running a tank dry. They never selected the other tank, but nonetheless the airplane was destroyed when it landed in a field 2 miles short of a runway. The prop lever was pushed to the full forward position and remained there for the entire descent, and it had a 3-bladed prop. Most likely they would have made the runway if the prop lever had been pulled completely aft.

Vic

Probably would have made it if they just switched tanks too..and been able to taxi to the fuel pumps!
 
Thanks for the replies.
To summarize:

If the engine is wind milling there may or may not be a chance to get the prop to course pitch but if I want a simple procedure that I can take from plane to plane it would be:

If unable to restart (Wind milling or not)
-Throttle FULL OPEN
(pumping resistance countermeasure)

- Propeller Control FULL AFT (OUT)
(depending on your planes configuration lever or slider)


Just to slightly complicate your simple procedure.

If you are doing a practice engine failure to low atlitude followed by a climb make sure to put the prop full fine at least a few seconds before adding power to give the prop time to go fine.

Fin
9A
 
Never heard the WOT part, but I can only assume that is only after you have the prop moved to coarse and now want it to stop rotating entirely. Much easier to turn an engine that is choked for air than one thats got a nice packed cylinder thanks to an open throttle.
 
From somewhere I remember that the min rpm that a governor is actually able to do its governing job is something like 21 or 2200rpm. Below that it matters not where you put the prop control, the prop is at its fine pitch stops. The only reason we put the prop control forward on final is so its set up properly when we bring the throttles back in if we have to go around - ie take off configuration.

Ive never had a case to test this, but does a dead motor really windmill that fast - 2100rpm? Doesnt seem likely, but again, this is all hazy to me that clearly needs better reviewing.

For that matter, if it is going 2100 in windmill, once you pull it coarse, it surely cant remain at 2100.....so it'll go fine anyway, no?
 
From somewhere I remember that the min rpm that a governor is actually able to do its governing job is something like 21 or 2200rpm.

Most governors will govern down to below 1700 RPM or so. Otherwise, when you tested it at 1700 rpm on run up, nothing would happen.
 
Never heard the WOT part, but I can only assume that is only after you have the prop moved to coarse and now want it to stop rotating entirely. Much easier to turn an engine that is choked for air than one thats got a nice packed cylinder thanks to an open throttle.
I don't think that's correct. Throttle at idle, the flow is choked, and the manifold pressure may be, say, 15". The prop-engine is now a vacuum pump, doing work (getting energy from the airflow) pumping air from the low pressure intake manifold to the outside (atmospheric pressure). Wide open throttle, the manifold is at ambient pressure, the engine does no work pumping air from the manifold to the outside. (ideal engine, of course).
 
Most governors will govern down to below 1700 RPM or so. Otherwise, when you tested it at 1700 rpm on run up, nothing would happen.

Ah yes. Thats right. I havent been flying in a few years - too busy building. But yeah I rem 1800 in the Citabria for mag and prop cycle.

So replace 2100 with 17-1800 and the question remains - does a dead motor prop windmill at 1700rpm? Dunno; my gut wants to tell me that something close to or below 1000 is more likely.....ie idle.
 
My prop will go coarse when windmilling. RV9A, 0 320, 9:1 pistons, Hartzell prop and MT governor.

At 70 kts with the mixture at idle cut-off and prop control full in:
Oil pressure 55 psi
RPM 1350

At 70 kts with the mixture at idle cut-off and the prop control fully out (coarse):
Oil pressure 50 psi
RPM 900.

My windmilling prop will not go coarse with a Hartzell governor

Fin
9A
 
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My prop will go coarse when windmilling. RV9A, 0 320, 9:1 pistons, Hartzell prop and MT governor.

At 70 kts with the mixture at idle cut-off and prop control full in:
Oil pressure 55 psi
RPM 1350

At 70 kts with the mixture at idle cut-off and the prop control fully out (coarse):
Oil pressure 50 psi
RPM 900.

My windmilling prop will not go coarse with a Hartzell governor

Fin
9A

Thats pretty interesting Fin. Thanks.

Anyone comment on what a Jihostrof/PCU does?
 
Probably would have made it if they just switched tanks too..and been able to taxi to the fuel pumps!


Yep, just need to run the ?air, fuel, spark? check and it would have been a non event.

For the other question, I have pulled the prop back on final at idle in the RV10 with both the PCU 5000 and MT governors and they both seem to work the same. RPM is probably around 1100-1200.

Vic
 
I don't think that's correct. Throttle at idle, the flow is choked, and the manifold pressure may be, say, 15". The prop-engine is now a vacuum pump, doing work (getting energy from the airflow) pumping air from the low pressure intake manifold to the outside (atmospheric pressure). Wide open throttle, the manifold is at ambient pressure, the engine does no work pumping air from the manifold to the outside. (ideal engine, of course).

The biggest effort in a windmilling internal combustion engine is pushing a slug of air against the compression stroke - reduce that air charge by choking off the throttle and the effort goes down.

Easy enough for anyone to test... Choke the carb of a lawnmower with your hand and pull the rope, then block the butterfly wide open and do the same. Much easier to pull when the carb is blocked. Same thing with a shop vac: block the hose with your hand and the motor speeds up. The motor sees less load because its moving less air.
 
Remember the OP question was engine failed, prop stopped. In this scenario there is no oil pressure to the governor thus flat pitch. Moving the prop lever to coarse pitch would do nothing. Also with an engine out your going to be trying for a restart with any altitude. The last place you want the prop lever is back. :eek:
 
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Unless the engine is seized or the prop blade is stalled, the prop should always be windmilling.

Barry Schiff did a video on this years ago on the ABC wonderful world of flying. He recorded a neat demonstration on the benifits of stalling your prop for better glide...if you get board.
 
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OK,

Here we go.....

We flew this afternoon to try and demonstrate the effects of windmilling in fine and coarse and to see if we could stop the prop and see what would happen.

Here is the safety related background - please Ladies and Gents, don't pass comment on how we did it, we briefed for a good 30 minutes regarding how, where what etc. Matt is a competent pilot, I am a check pilot and test schedule pilot on light airplanes, so here goes.

The demonstrations were done in our RV7, IO-360, MT 3 blade hydraulic prop.

We settled on a location overhead a disused 13,000' runway :D

We started at 7,000' :D

We cooled the motor prior to the exercise and warmed it for the climb :D

We had a hard deck set at 4,000' for termination of exercises :D

We briefed exercises, order and possible anomalies prior to the test :D


Gosh - got that out of the way, now here is the skinny !!!


Set around 75kts trimmed, around 10" of MP, fine pitch, switched the P-Mags off and the ignition, went to ICO, so no power from the motor. It windmilled and stayed trimmed at the speed and settled at around 1,000fpm descent. Repeated with fully coarse and it settled a bit more at 1,200fpm but then back to 1,000fpm.
At this point, cycling the prop gave a noticeable change. In fine, there was braking, in coarse, it felt as though there was less resistance.

Finally, we tried to stop the prop - Hahahaha

This is Prop 2 video

I tried at stall, hmmmm, I tried with flap, hmmmmm, I tried a bit of a whip stall, hmmmmm.

I could have stopped the prop but only by being brutal and covering the belly with oil - did that last week with exuberant aeros, not again ;)


Conclusions.....

Well, over to you now - you have seen a demonstration, OK, it is a bit relaxed, we aimed to get both fine and coarse demonstrated which we did, we showed the effect of cycling fine to coarse with the motor in ICO.

If I had an engine failure, then yes, I would definitely pull the prop back, it may give me the extra 1/2 mile I need and while windmilling, if I needed more braking low down, it is an option.

A very interesting flight, we both enjoyed it, I think we have interpreted the OP question and feel free to contact off line if you wish to discuss :D

Mike and Matt


Vid Links

Prop 1 https://youtu.be/OLnEKdKt15M

Prop 2 https://youtu.be/CakLtPkQTIM
 
I don't think that's correct. Throttle at idle, the flow is choked, and the manifold pressure may be, say, 15". The prop-engine is now a vacuum pump, doing work (getting energy from the airflow) pumping air from the low pressure intake manifold to the outside (atmospheric pressure). Wide open throttle, the manifold is at ambient pressure, the engine does no work pumping air from the manifold to the outside. (ideal engine, of course).

Im with Bob on this one. Less suction from pistons moving down due to the lack of resistance from a closed throttle plate.
 
Whose governor (mfg) do you have again?

Did you happen to note dead motor RPM and oil pressure while windmilling?
 
I heard you guys call 1300 once, but not otherwise.

MT advertises their min rpm at 1400, so thats good that it did what it was supposed to. The other mfgs I couldnt find min numbers on the net.

I'm surprised that coarse didnt drop the rpm, but I guess there mustnt be a huge enough blade angle difference to make it notable.

I couldnt tell , but I gather you didnt change throttle settings ie WOT, just prop right......?
 
True dat Michael. Dyxlexckia kicking in again. One possible checklist procedure may be.......

1. Determine if accomplishing a restart is prudent
2. Accomplish a complete shutdown to include fuel selector valve-off, mixture-cut off, propeller controll-full aft ?coarse?.

Just for good measure.
 
Didn?t change the throttle.

As I said, it was a simple comparison, basically to see differences. The feel was that there was less drag in coarse pitch, it is a 3 blade prop and we have std pistons, so not huge compressions - I wasn?t surprised that the prop wouldn?t stop.
 
Well done

Well done Mike and Matt.... and thanks
Bob
I’ll buy the beer ar OSH
 
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