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From: "John R. Johnson" <>
Newsgroups: rec.aviation.homebuilt
Subject: Re: Instructor shutting engine off in flight
Date: Tue, 1 Jul 1997 12:16:10 -0500

On Tue, 1 Jul 1997, Ron Natalie wrote:

> > If there is actually a rule of some kind? I would greatly appreciate
> > the reference or if not some explanation why I could have gotten that
> > impression.
> There's no rule other than perhaps the catchall 91.13: Careless and
> Reckless operation.  Chances are nothing will come of it until the
> time an accident occurs subsequent to one of these tests.
> I've had it done to me, admittedly when I was directly over a
> (then) quiet airport with lots of runways and grass landing
> areas.  However, I really don't think that the extra "realism"
> over idle really makes much difference over the instructor
> pulling back and guarding the throttle.  On things other
> than simple trainers, it gets even more dicey.
> I just don't see the benefit vs. the risk here.

We have been around this tree before.  I believe you can make an excellent
case that pulling the throttle back still allows fuel evaporation in the
carb throat around the throttle body and leaves you prone to ice buildup.
Of course carb heat is normally pulled on the same time the instructor
pulls the throttle back.  However, the heat source for the carb heat is
gone in seconds.  It is quite possible that the engine will fail to
respond when the throttle is moved forward again.  We had several accidents
here in Southern Illinois from that cause.  One was serious and resulted
in both the instructor and the student haveing major back injuries when
they lost it and stalled in from about fifty feet trying to stretch the
glide to a landable spot.

On the other hand, if I merely pull the mixture to idle cutoff, there is
no fuel evaporating in the carb.  No chance of carb ice.  When I return
the mixture to rich, the windmilling engine will start smoothly and
immediately and we will have full power.

It is probably an even odds proposition which will give you the best
chance of regaining power on demand after the power off excercise.  I
really don't see any significant difference in safety between the two
techniques for a power off simulation.


From: "John R. Johnson" <>
Newsgroups: rec.aviation.homebuilt
Subject: Re: Instructor shutting engine off in flight
Date: Wed, 2 Jul 1997 11:47:01 -0500

On 2 Jul 1997, Jeffry Stetson wrote:

> In article <Pine.SOL.3.91.970701121044.2709o-100000@reliant>, says...
> >
> >On the other hand, if I merely pull the mixture to idle cutoff, there is
> >no fuel evaporating in the carb.  No chance of carb ice.  When I return
> >the mixture to rich, the windmilling engine will start smoothly and
> >immediately and we will have full power.
> >
> I'm not sure I agree with this.  The carb still represents a restriction
> in the induction system; air accelerates, pressure drops, air cools.  It
> doesn't require evaporation to accomplish this.  Granted, evaporation
> must make it worse.

That is true, Jeff.  However, the major share of the cooling in the carb
comes from the "heat of evaporation" of the fuel.  This is the chilling
you feel when you spill fuel on your hands when refuelling.  The temperature
drop that goes with the pressure drop is relatively small.  It could cause
icing is you were very close to freezing outside and the weather was quite
humid.  It depends of the dew point spread.


From:  (Badwater Bill)
Newsgroups: rec.aviation.homebuilt
Subject: Re: Instructor shutting engine off in flight
Date: Wed, 02 Jul 1997 16:12:10 GMT

On Tue, 1 Jul 1997 12:16:10 -0500, "John R. Johnson" <>

>On Tue, 1 Jul 1997, Ron Natalie wrote:

>We have been around this tree before.

When I was young and dumb I was training a guy in a C-150-150.  I
pulled the mixture on him downwind and he made some mistakes getting
to the runway.  On short final when I saw we weren't going to make it,
I shoved the mixture back in but nothing happened, no power.  We hit
the overrun just past a big ditch and then rolled on to the runway.
We got to live, but it was not due to anything I did.  I never put
myself or a student in that situation again (that was 30 years ago).


From: "John R. Johnson" <>
Newsgroups: rec.aviation.student,rec.aviation.misc,rec.aviation.homebuilt
Subject: Re: Instructor shutting engine off in flight
Date: Mon, 7 Jul 1997 10:06:35 -0500

On 4 Jul 1997, Andrew M. Sarangan wrote:

> I have not followed this thread, so forgive me for this.
> I cannot disagree more with turning off the engine to practise forced
> landings. I am sure it is a very valuable exercise, but the risks
> associated with that exercise is just not worth it, not to mention
> breaking the law.

You do have a point.  The risk of an accident as a result of turning off
the engine by pulling the mixture control is actually slightly less than
the risk of an accident by simulating an engine out by pulling the throttle
back to idle and running an overrich fuel mixture through the cylinders
with minimal heat production.  However, because so few people actually
understand what is going on INSIDE the engine in the two different cases,
the risk of being SUED following an accident is substantially greater
if you simulate the emergency by pulling the mixture control.  This is
typical of aviation problems these days, where emotion overrides reason.

> Those who like practising real engine-outs should also consider flying
> with their pitot/static ports covered. That will a valuable experience
> in flying without ASI or altimeter. After all you should know how to fly
> without instruments.

Absolutely.  You should DEFINATELY have this experience.  Otherwise you
could very well have a serious accident the first time a little moisture
condenses inside your pitot line or a wasp finds your static vent an
attractive hole, or builds a nest in your pitot tube.  I can think of a
number of times when I took off after a THOROUGH preflight, and found
my airspeed indicator working like a poor altimeter!

Of course, a readily reversible technique is preferred, such as sticking
opaque suction cups over the instruments.  It would be vastly better to
have an unobtrusive valve manifold that would allow the instructor to
simulate these problems as they would occur.  There have been many fatal
accidents because a primary instrument failed in flight and the pilot
was not aware of the failure and followed the failing instrument into
serious troublem  Unfortunately, a number of these fatal accidents did
involve air transport category aircraft, like the recent case where the
jet full of passengers took off with masking tape blocking the static
vents.  It would NOT have been fatal if the pilots, either of them,
had recognized the indications of static failure promptly.  Unfortunately,
they had not been sufficiently exposed to such failures.

> Another useful exercise is to intentionally fly into IMC conditions
> during your training. Since some hood time is required for VFR anyway, why
> not make it real and true-to-life ? You never know when that experience
> might come in handy and save your life some day.

Absolutely.  There is no substitute for some "actual" instrument flight
for a student.  It is certainly advisable to experience real IMC for the
first time with an EXPERIENCED CFII sitting next to you.

> I am sure an even better exercise is to fly IMC with a broken AI.
> Think about the adrenalin rush and the fear as you have to fly partial
> panel. After all you have to know how to fly partial panel IFR, and might
> come in real handy some day.

Yes, I strongly recommend that experience.  It saved my life!

> Of course, the above comments are meant to be sarcastic, not serious!
> Don't try them, not even in your dreams!

They were perhaps meant as sarcasm.  Please try all of the above with an
appropriate instructor if it is at all possible.  There are some very
important things that you just cannot learn from a simulation, and none
of the above things are actually emergencies.  If it is NOT an emergency
situation why not experience the real thing under controlled conditions,
instead of saving the practice for a real emergency when you life depends
on you unformed skill.

Of course, I would not recommend creating a REAL emergency for practice.
Please do not start any fires in the back seat, or punch holes in the

Please DO:

1.  Kill the engine, by pulling the mixture control.

2.  Open a door.

3.  pinch off the static line if you can.

4.  pinch off the pitot line if you can.

5.  take me into REAL imc to practice ifr reference flight.

6.  Let me fly an instrument approach with REAL clouds, maybe not
    to minimums, but to a reasonable cloud base.

7.  Hold the throttle OPEN when I want to land.

8.  Disallow the flaps with them up.

9.  Disallow the flaps with them DOWN.

10.  Let me simulate a power failure all the way to a landing if it is
     safe to do so.


John "for safer flying with knowledge" Johnson

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