Finding best forum to ask & explain:

[hoggsnortrupert]

ENGINE OUT TRAINING, ZERO THRUST:

Over the years I have lost count of the times when doing a base check (OPC), where upon an engine is failed and ZERO THRUST is then set:

This setting being one that is suppose to as close as possible simulate a feathered prop.

Usually used within the “circuit/pattern altitude” where it is not desirable to feather a prop (Training remember)

At altitude however on Jet Props I have found it the norm to just feather the thing and keep it at IDLE.

What I have noticed over the years is that some “Checkies” don’t understand the principle involved.

The common being in the circuit/pattern is where it tends to get murky!

On this occasion however he wanted the Failed engine Power lever to be kept at IDLE, and the PROP kept at full fine position.

I have recently joined a NEW operator, doing a post sim base check, (returning to play with my toys after a couple of years break & recuperation of my body clock, to be able to s—t properly again is indeed a joy to behold)

During the pre flight brief “HE SAID” any engine failure would be conducted using ZERO THRUST, as I am not a fan of the practice of feathering propellers! (Direct quote) at the time I didn’t pay too much attention to this apart from think to myself, it is kind of weird!

Thus I have just had a “blue” with the chap checking me, after I suggested very nicely, that leaving the Power Lever at Idle, and the prop at the failure setting, (Fully Fine) was detrimental to the performance. (Climbing FL160-180)

The exercise I was proceeding with was an engine failure at FL160, (gear down-flap 15) a go around, clean up, climb to FL180 then a series of Steep turns, followed by a couple of stalls.

Upon calling for feathering of the prop, he did nothing and said, “feathered”! I suggested bringing the prop to the min governing position, and setting power just above idle, his voice rose and he said NO! This thing has condition levers! They work different to your old Twin-otter?? (Don’t see it myself)

I proceeded to do a bit of fine-tuning, by moving the L/H prop lever to the MIN GOVERNING position, he moved his hand to prevent me, and said, “Don’t touch the prop I am not in the position of tempting fait”!

This engine failure procedure “I” refer to, is as I was originally taught in the USA, by an Okalahoma based FAA check Airman back in 1986, Mr “G.V” and subsequently has held me in good steed wherever I have worked previously on the DHC-6.

On occasion when a C & Tg person asked me why I would position the prop at min governing and power just above that of idle, I would explain, and demonstrate the effect, upon doing so It was always taken on board:

Please! can you tell me, have I been wrong all this time?

Up until 2005 I held a training position on a multi jet prop.

I have been through the DHC-8 flight manual looking for any reference to ZERO THRUST SETTING, and have not been able to find anything.

Personally at FL160-180 I would feather the bloody thing and get on with it.

Chr’s.


H/Snort::(

[waren9]

Sounds like his idea of zero thrust isnt quite right. What he was insisting on sounds to me like a prop that is being driven by airflow and not the engine, which of course, is worse than zero thrust as you rightly point out.

How did he not fathom the difference between min rpm and feathered?

I use the debrief at the end of a check to sort stuff like that out and I find that if you ask for a diagram on a whiteboard they usually end up talking themselves round sooner or later.

If he needs proof that its the airflow driving the prop at max rpm and pwr lvr at idle in flt, ask him why that same rpm cannot be achieved on the ground when condx lvrs max, and pwr lvrs at flt idle?

Failing that, when you find the reference in a book, photocopy it and quietly leave it in his drop file for him to find.:ok:

[Pilot DAR]

Hi Snort,

This is an issue I have dealt with in pistons, and to a limited degree in turbines.

In the pistons, Cessna 310 in particular, there was a flight manual stated "zero thrust" power setting to use during training. As I recall form all those years ago, it was 1250 RPM and full fine (though I am subject to weak memory on the exact value). The rationale for this is that the prop was to be left at full fine in case power was needed quickly. With the prop in full fine, it would create drag at idle power which would exceed that of a feathered prop, because the air was driving the engine. By setting the power to 1250 RPM the engine would drive the prop just enough to balance off the force of the air driving the engine, and the net effect was equal to zero thrust. We did actually shut down piston engines and feather them at altitude a few times, but they are not so happy to restart, and let alone the obvious safety shortcoming of this, I think it's just un-necessarily hard on the engine.

In turbines it has been my experience that the engine was left running at idle, and the prop was feathered. during recent flight testing in a turbine powered DC-3, I enquired of a zero thrust power setting, and the training pilot with whom I was flying told me that they just feathered it and left it running, which we did. This was also my experience with Twin Otters.

That said though, I am a fan of establishing a zero thrust power setting, a touch above idle, and using that when close to the ground, so it is not necessary to wait for the prop to come back into fine pitch if you suddenly need the power. It is a pilot instinct to advance the power when it's needed, it's not quite the same instict to unfeather a prop, wait for it, and then add power. I think that any organization who regularly trains should determine for them selves a suitable training zero thrust setting, and use it by company policy. It does not need to be right on to be effective and safe, anywhere close will result in the desired training effect.

Pilot DAR

[camlobe]

I can't personally comment on the turboprop aspect, but with regard to piston multi's, zero thrust below 3000', feather above 3000'. And yes, I do know people who haven't been able to restart the feathered engine.

As mentioned above, zero thrust settings leave the prop in fine pitch with a manifold pressure normally between 11 and 13 inches. This configuration gives (in theory) realistic feathered engine drag with a rapid-response capability if you need to use the engine.

Maybe we have been doing it wrong.

camlobe

[WeekendFlyer]

With a turboprop there should be a power lever setting that gives drag equivalent to that present when the engine is shut-down with a fully feathered prop. this technique is used quite a lot in flight test when it is necessary to test the asymmetric performance and handling of the aircraft but without the risk associated with having an engine shut-down. As previous posters have stated, it is nice to know an engine is available quickly if needed!

As for identifying the best power lever setting for simulated asymmetric flight, it is fairly easy to do if you have rudder angle and sideslip gauges available, but slightly harder on an un-instrumented aircraft. One technique that would be worth trying is to establish the aircraft in straight and level flight with one engine shut-down and feathered, then note the speed, rudder and aileron trim settings used, and also the angle of bank. Then repeat with that engine operating and see what power lever setting will give you the same combination of speed, bank angle, rudder and aileron trim in order to maintain straight and level flight. A similar exercise could be done in the climb if required, maintaining speed and rate of climb as well as bank angle and trim settings.

If you decide to try either of the above I would caution: 1) make sure you have enough height to recover and restart the shut-down engine if it is needed in a hurry, 2) be very careful with respect to VMCA, your stall speed and any sideslip or rudder related limits, 3) get a radar service to help with you traffic awareness, 4) know what you will do if the good engine quits, if you come close to a limit (e.g sideslip, speed). I'm sure other regulars on this forum could probably add more things to consider as well. And to be frank, before trying any of the above it would probably be worth a chat with the aircraft manufacturer, because they will probably have established the necessary power setting during early flight testing and certification anyway!