Simulated Engine Failure – Throttle or Mixture

[dragchute]

Simulated Engine Failure – Throttle or Mixture

Elsewhere there is discussion in the post ‘Airtours C404 Crash Report’ on simulating engine failures during training. A number of writers make mention of the instructor ‘retarding the throttle’ to simulate an engine failure. It is my understanding that simulating an engine failure by closing the throttle leads to the possibility of serious damage to the gudgeon pins, con-rods and possibly the crank-shaft.

For that reason I and many other instructors use the alternative method – leaning the mixture to ICO with the throttle remaining in the power-on position. Certainly within Australia this seems to be the norm. Are those writers, who seem to be UK based, simply using poetic license by referring to the throttle or is that the means used within that region? What do other instructors think about the issue of throttle –v- mixture control?

[hugh flung_dung]

The standard advice (and UK practise AFAIK) is to use mixture above 3000 ft and throttle below 3000ft - this came from a Lycoming publication a few years ago that I now can't find.
Mixture is kinder to the engine but recovery can be delayed if stude does the wrong thing or if the "live" engine chooses that moment to fail for real.

[Hudson]

From Seminole POH, Section 10 - Safety tips, paragraph (l).Date of issue March 23 1978.


Quote: Experience has shown that the training advantage gained by pulling a mixture control or turning off the fuel to simulate engine failure at low altitude is not worth the risk assumed, therefore it is recommended that instead of using either of these procedures to simulate loss of power at low altitude, the throttle be retarded slowly to idle position.
Fast reduction of power may be harmful to the engine. A power setting of 2000RPM and 11.5 in.Hg MAP is recommended for simulated one engine operation. Unquote.

As far as I am aware there has been no published amendment to that philosophy, therefore it would safe to say that the advice is still valid for 2001. Certainly any litigation would rely heavily on that advice.

Pulling the mixture to simulate engine failure after take off certainly gives a dramatic engine failure but there is no shortage of stories to indicate that students can whack on full wrong rudder in error. To recover power to the engine, the instructor must first close the throttle on the "failed" engine - then place the mixture lever from cut-off to rich - then advance the throttle back to high power. Plus recover flight control from what could be an alarming attitude. Very busy man, the instructor....

Depending on the urgency of the situation, and particularly if the student pulls back the incorrect throttle in error while attempting to identify the "failed" engine, the instructor will be working like a one arm wall paper hanger to restore symmetric power.

Pulling the mixture to simulate engine failure may have have its advantages in terms of surprise factor and desirable engine operation, but as soon as the mixture is cut, the drag is instantaneous and if not immediately corrected by engine restart and setting of zero thrust, a potentially dangerous bleeding off of airspeed can result.

In short, if all students were perfect pilots, then a mixture cut at low level is fine because nothing could go wrong ever.

But unfortunately there is a real world out there and students have been known to over-react and make mistakes.

Instructors who cut the mixture at low level to simulate engine failure are putting lives at risk. I can see the lawyers sitting ready to pounce on the instructor, the supervising CFI and the flying school operator. And quite rightly so.

[Checkboard]

Discussed on the Instructor's Forum on the following threads:

Turning off the donkey in flight. Yes or No? (http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=get_topic&f=5&t=000131&p=), and
Reducing the risks in engine out training (http://www.pprune.org/cgibin/ultimatebb.cgi?ubb=get_topic&f=5&t=000621)

Feel free to continue the discussion there.