Van_Hoolio said:
Oh sorry, the DE applied full power on downwind and used the flaps to slow it down so you could fly the rest of the pattern and towards the end of the runway at a reasonable rate (and with a shload of nose down trim!). The DE suggested pulling the mixture when the field is made, but I'd lean toward using the mags to kill the engine so you might have a better shot of getting the engine back if you wanted it. I could be wrong on that one though.
Mike
Cutting the mags off or the mixture both accomplish the same thing, in slightly different ways. 3 things needed for combustion; fuel, spark, air. If you cut the mags, you take away spark.........cut the mixture and you take away fuel. So long as the prop is still windmilling, you've got the air being drawn into the cylinders. It's been my experience that someone who says they wouldn't use the mixture, doesn't completely understand how an aircraft engine works. My point in this discussion is to say cutting either one gives you the same chance of getting the engine back should you need it (and either one has, in my opinion, the same potential for failure). Mixture back in, fuel is back in the picture with the already occurring spark and air. Mags back in, spark is back with occurring fuel and air. Personally, I'd be more comfortable using the mixture to cut the engine, though I have no definitive answer to why. Also, keep in mind, on short final (if you're on speed, at least in typical training planes) the prop will quit windmilling, albeit not immediately, so this may be a moot discussion. See below how I know this, but once the mixture's out, you've got about 15-20 secs before the prop quits.
On an aside, this is actually something I do with my students at least once.........simulated engine failure with throttle to idle, once I *know* we'll make the runway (and there's not another airplane *anywhere* near the runway that may pull out in front of us, etc), I pull the mixture and let the engine completely stop. Just one way I make my training as realistic (yet balancing experience gained against safety) as possible. They may have done 100 sim engine failure landings, but every time I do this and they land with a stopped prop and silence they always comment on how different it actually is, and thank me for showing them what it would really be like, should it actually happen someday.
And before anyone gives me grief about this, I'll say this. I think anyone with a CFI certificate (perhaps with a couple hundred hrs dual given, so they have some experience/judgement seeing how students react?) should be competent enough to evaluate the situation in terms of potential gotchas (ie: traffic holding short), and if necessary be able to recognize a bad situation before it gets bad and take control to get the plane down safely.
Back to the original topic, if anyone can give me a reason the mags may be a better choice than the mixture (ie: one could fail more readily and WHY that would happen), I'm not above changing my ways.
