Why We Don't Pull Mixture!!!
Dudley Henriques
about this subject. Some of you have had positive experiences in dealing
with this issue, and that's good. Every experience, whether positive or
negative should be a learning experience in an airplane. We all agree on
that! What we would like to do is keep those negative examples to a minimum,
since the overall goal is to remain in one piece after the lesson is over.
Now, why is it unnecessary to pull mixture to idle cutoff in a single engine
airplane to demonstrate to a student that the glide characteristics will be
changed with the propeller stopped? Let's deal with this one question,
because when it comes right down to it, it's this that seems to be causing
some confusion.
It's not written in stone how an individual instructor is allowed to
demonstrate a particular maneuver or aspect of flight training to a student.
The powers that be have decided long ago that if left alone, most CFI's will
naturally find the best solution as it relates to their individual teaching
methods. The fuzz concentrates on the finished product of that teaching
during the flight test. The examiner pulls the throttle for either a high or
a low altitude emergency; then watches as the applicant either solves the
problem that's presented, or screws it up. Either way, it's the result that
is judged.
In teaching students forced landings and in-flight emergencies, most of us
who have been doing it for awhile have learned that the statistics involving
simulated emergencies turning into actual emergencies are eye opening to say
the least. Fortunately, in teaching emergencies, it just so happens that the
optimum method for doing this coincides with improving the stats. If you
examine the plus and minus sides of this issue you begin with the goal; that
being to impart on the student the knowledge and skill required to react
properly and perform properly in an emergency situation; in this case, an
engine failure. Pulling the mixture to idle cutoff is viewed by some as
beneficial in two areas.
1. Presenting the student with a sudden, startling problem so that he/she
can obtain experience with the "shock" that always accompanies a total
engine failure.
2. A demonstration to the student of the different glide characteristics
between a windmilling propeller and a stopped propeller.
Now, on the surface this appears to be a worthy goal, but let's go a bit
deeper into the problem; examining it more closely.
What's the down side on pulling the mixture to idle cutoff?
1. Shock cooling
2. Broken mixture cable
3. Fuel related problems on restart
4. Broken starter
5 Unforeseen engine component failure that denies restart
....and on an actual dead engine approach followed to landing.....errors in
judgement resulting from any mistake....the inability to solve a problem
presented at touchdown by incursion or obstruction.
Now, let's take this and put it in perspective. Does the risk justify the
means? The answer is an emphatic NO!!! The reasons for this were discovered
years ago, and here they are.
1.Pilot shock during total engine failure will occur regardless of a prior
demonstration. The proper way to reduce it's impact is through a careful
presentation to the student, given on a continuing basis; stressing that it
should be EXPECTED, and dealt with as the first item on the emergency
checklist.[ i.e..shock felt...shock expected...shock gone...handle
emergency!] This process with proper training can be reduced to seconds.
Without proper training it's worthless to induce pilot shock. The result is
usually a brain freeze followed by confusion and over tasking. In general,
just yanking the mixture to idle cutoff is considered bad instructional
reasoning.
2. The windmilling propeller problem as opposed to the stopped propeller. It
goes without saying that a stopped prop will change the glide ratio. To kill
the engine to demonstrate this is not necessary; and for this reason.
Assuming a high altitude engine failure that has been determined as
unsolvable through normal checklist procedures,regardless of the glide
ratio,[stopped or windmilling] after the airplane has been stabilized at max
glide, the completion of the forced landing is accomplished by VISUAL CUES.
This means that REGARDLESS of the glide ratio presented by the prop
condition, the pilot should be reacting to what the AIRPLANE IS TELLING
HIM/HER at ANY SPECIFIC INSTANT IN TIME. I can't stress this enough. Forget
the graphs and charts. You should already know that the glide ratio is less
with a windmilling propeller. Expect that! Your only concern should be
placing the airplane at a chosen key position at the right altitude. With
the airplane stabilized at max glide, the sink rate becomes a constant. What
you have to do is choose the correct angle of bank to produce the turn
required to put you where you want to be....period!
The bottom line on all this is simply that if taught correctly, a student
pilot and the airplane need not be subjected to the risks stated above in
order to learn proper emergency procedures. Most of us in the instruction
community don't pull mixture and cut switches for the reasons I have given
here. Granted, you will find those who believe yanking mixture and cutting
switches is good practice.
It's up to each pilot out there to find out for themselves what is correct
and not correct. I strongly suggest that before you decide which is the
right approach to this problem, you seek out competent FAA opinion on the
matter.
--
Dudley A. Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI/Retired
Roy Smith, CFI
> The examiner pulls the throttle for either a high or a low altitude
> emergency; then watches as the applicant either solves the problem that's
> presented, or screws it up.
Somewhere along the line, a DE I took a checkride with had a different way of
doing this. He told me before the ride that when the time came to
demonstrate an engine-out, he would tell me, and *I* would be the one to
retard the throttle. The reason for this, he said, was that if the engine
ever died unexpectedly in flight, there would be no doubt that it was truly
an engine failure, and not just a drill. Left unspoken, I suspect, was also
an attempt to shift liability in the case of an accident :-)
In any case, I've adopted this idea into my own teaching. I never pull
throttles (or mixtures!) on my students. Before the flight, I explain that
when we do engine-out drills, I'll tell them, and they'll bring the throttle
back to idle. I also have them do the engine clearing drill. Sometimes I
make the signal to start the drill me shouting BOOM!, with the explanation
(beforehand) this is to simulate the noise of a piston rod punching a hole in
the crankcase.
One of the reasons I like to do it this way is because it gets the student
used to the idea that they *may* pull the throttle to idle by themselves, and
it's not some holy procedure which may only be performed by a high priest. I
remember when I was a student, the school had a rule that students shall NOT
practice engine-out drills solo. While I can understand their concern, I
think in the long run it's a good thing for pilots to get into the habit of
doing engine-out drills on their own. Otherwise the only practice they ever
get is a couple of attempts every other year at BFR time.
I also remember my student days, when whole flights would go by with me being
on knife-edge, just waiting for the engine to die. At one point, I even got
into the habit of flying with one hand on the throttle at all times, because
I knew that as long as I did that, the instructor could not surprise me with
an engine failure. Anxiety like that just inhibits real learning.
--
Roy Smith, CFI-ASE-IA
Dudley Henriques
"Roy Smith, CFI" <r...@panix.com> wrote in message
news:roy-ED86D8.1...@news.panix.com...
These are all good points Roy, especially about student anxiety. The old
system of "throw them into the river and they'll learn how to swim" has long
ago been discarded by competent flight instructors who like you, realize
that the shock treatment not only impairs the learning process, but actually
can be used as a negative example of good flight instruction technique.
There is no better way to prepare a student for an emergency than to teach
all the theory on the ground; then reduce the problem to it's lowest common
denominator[ simplicity] while in the air. A student who has been well
prepared and indoctrinated to emergency procedure[ and this includes the
expectation of sudden shock] will as a matter of course, react to that
emergency as he/she was trained to react.
Jim Weir
shared these priceless pearls of wisdom:
Sometimes I
->make the signal to start the drill me shouting BOOM!, with the explanation
->(beforehand) this is to simulate the noise of a piston rod punching a hole in
->the crankcase.
Roy --
I like that "BOOM" idea. Goes to show you no matter how long you've been
sitting in the right seat, you can always learn something new from another
instructor.
Thanks.
Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com j...@rst-engr.com
Steve Porter
throttle is that some students like myself fly with their right hand resting
on the throttle. When I started practicing engine failures with an
instructor that pulled the mixture, he told me not to let the airspeed get
too low while trimming for best glide in case the prop stopped.
Steve P.
flyi...@my-deja.com
"Dudley Henriques" <dhenr...@earthlink.net> wrote:
> Keep in mind ladies and gents, that it's not my intention to start a
war
> about this subject.
Dudley
I am trying really hard not to get into an argument with you. How may
engine outs have you experienced? How many emergencies?
It is one thing to speak from book reading, and quite another to
speak from actual experience.
I await your reply.
FlyinRock
Sent via Deja.com
http://www.deja.com/
flyi...@my-deja.com
"Dudley Henriques" <dhenr...@earthlink.net> wrote:
war
> about this subject.
Dudley
I am trying really hard not to get into an argument with you. How may
engine outs have you experienced? How many emergencies?
It is one thing to speak from book reading, and quite another to
speak from actual experience.
I await your reply.
FlyinRock
Dudley Henriques
<flyi...@my-deja.com> wrote in message news:94vn27$k01$1...@nnrp1.deja.com...
> engine outs have you experienced? How many emergencies?
> It is one thing to speak from book reading, and quite another to
> speak from actual experience.
Oh, I've had my share of ups and downs. :-)))
Really, I don't want to get into a big "can you top this" with anyone.
In the unlikely event that anyone would have nothing better to do with their
time than be interested in my humble tenure in aviation, it happens that two
websites are featuring some information about me at this time. Try
www.migman.com You will find me listed under pilots between Gabreski and
Yeager.
Best regards,
rstowell
Hi Dudley,
Excellent post, and not because I happen to agree with you ;)
Rich
In article <zjBc6.4867$OR1.5...@newsread2.prod.itd.earthlink.net>,
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Rich Stowell, Author--Instructor--Speaker--NAFI Master CFI
Aviation Learning Center, http://www.richstowell.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Michel Pelletier
On Sat, 27 Jan 2001, Dudley Henriques wrote:
> These are all good points Roy, especially about student anxiety. The old
> system of "throw them into the river and they'll learn how to swim" has long
> ago been discarded by competent flight instructors who like you, realize
> that the shock treatment not only impairs the learning process, but actually
> can be used as a negative example of good flight instruction technique.
Not to mention that people DROWN and DIE (to extend your swimming
metaphor). I agree with you, I just wanted to point that out. ;)
-Michel
Michel Pelletier
On Sat, 27 Jan 2001, Dudley Henriques wrote:
> 2. The windmilling propeller problem as opposed to the stopped propeller. It
> goes without saying that a stopped prop will change the glide ratio. To kill
> the engine to demonstrate this is not necessary; and for this reason.
> Assuming a high altitude engine failure that has been determined as
> unsolvable through normal checklist procedures,regardless of the glide
> ratio,[stopped or windmilling] after the airplane has been stabilized at max
> glide, the completion of the forced landing is accomplished by VISUAL CUES.
> This means that REGARDLESS of the glide ratio presented by the prop
> condition, the pilot should be reacting to what the AIRPLANE IS TELLING
> HIM/HER at ANY SPECIFIC INSTANT IN TIME. I can't stress this enough. Forget
> the graphs and charts. You should already know that the glide ratio is less
> with a windmilling propeller. Expect that! Your only concern should be
> placing the airplane at a chosen key position at the right altitude. With
> the airplane stabilized at max glide, the sink rate becomes a constant. What
> you have to do is choose the correct angle of bank to produce the turn
> required to put you where you want to be....period!
Bingo. I can use my own brain and learn given an example, a
demonstration, or an explanation. Thank you, Dudley, for this very common
sense explanation which I will not forget, even if my engine has failed.
You have sealed the argument for this mere 4.5 hour student.
Those who insist that a demonstration is the only way to "really" learn
are either stupid or dead or soon to be both. It's no problem to me when
they bite it cuz that just improves the gene pool, but it's a terrible
thing when its demonstrated on someone who doesn't know better, like a
child, or a *student*. Maybe some of you should learn to teach *that*.
"Shee-it, that cattle wire won't hurt yah, just a little zap. Watch!"
"Whatever you do Bobbie, you should not point the loaded gun at your face
like this. That's how uncle Jimmy died."
"Now if you stand behind a horse just like I'm doing, you make him
nervous, and he might kick you."
"Don't got no wheel chocks, just set the parkin brake and she won't roll
off the jack; do it all the time. Watch."
"Yeah my brother Jimmy was a pilot till they axed him for too many runway
incursions. Now let's kill that engine. Don't worry, she'll fire right
up."
No thanks, I'll just watch from over here.
-Michel
AV8R2B
face.
Dudley, nice to see someone of your stature in aviation on this newsgroup.
Thanks for spending your time here.
Matt Johnson
Dudley Henriques <dhenr...@earthlink.net> wrote in message
news:cvJc6.1004$2t5.1...@newsread2.prod.itd.earthlink.net...
Keith Dingle
flyi...@my-deja.com
"AV8R2B" <just...@tospam.com> wrote:
> Can somebody hand FlyinRock a towel? He's got a lot of egg to wipe
off his
> face.
Not a chance of that! I have my experience to lean on. I have my
background in general aviation worldwide. Dudley and I will continue to
have our differences of opinion and instructional techniques. I make no
apologies and am pretty damned proud of my reputation earned over 40
years of flying. Got no egg on my face at all.
FlyinRock
Tim Helton
> have our differences of opinion and instructional techniques. I make no
It's people like Dudley (and Gene Whitt, Ron Gardner, John Lowre, et al.)
that make these aviation newsgroups such an amazing resource... Imagine
walking into you local FBO and hanging out with people like this!
100 hour smucks like me really appreciate the insight that these folks
give... And we'll appreciate your experiences too!
tim
PP-ASEL
flyi...@my-deja.com
Keith
I quite agree with you but you are missing the point here. There is a
huge difference in just stopping the engine with fuel starvation as
opposed to intentionally stopping the prop.
Many years ago I had a piece of prop come off shortly after take-off
from a sand bar in the Amazon. I managed to stop the prop to keep the
engine from shaking off the aircraft, did a 180 and got it back on the
ground without further damage. The prop apparently took rock damage
during takeoff and shed a 4" piece of prop. Could I go anyplace else?
Nope. It was at least 100 miles to the next airstrip and in hostile
country. Hero? Nope. Just a competent pilot. Did I use that experience
with future students? Yep. Will they ever need it? Who knows! Do I ever
put a student at risk? I don't think so. Is flying risky? Damned right
it is! Is driving on the Interstate risky? Of course it is.
All I am saying is I teach from a position of experience and have done
so for more than 35 years and more than 22,000 hours of flying in
general aviation aircraft.
Best Regards
FlyinRock
Ron Natalie
"Roy Smith, CFI" wrote:
>
> "Dudley Henriques" <dhenr...@earthlink.net> wrote:
> > The examiner pulls the throttle for either a high or a low altitude
> > emergency; then watches as the applicant either solves the problem that's
> > presented, or screws it up.
>
> Somewhere along the line, a DE I took a checkride with had a different way of
> doing this. He told me before the ride that when the time came to
> demonstrate an engine-out, he would tell me, and *I* would be the one to
> retard the throttle.
Besides, unless he is overly familiar with the airplane, it may be
a mistake to go messing with the controls. I've smacked a few instructors
who tried to be "helpful" with the prop control in my plane. I had to
abort a takeoff after some gratuitous playing with the mixture control
by another. Geared engines, non-constant-speed but variable pitch props,
and altitude adjusting carburators are not something most instructors
are familar with the nuances of.
Ron Natalie
My instructor broke me of that (once we are above 400' or so). He promissed
me I could get to it before we hit the ground.
Julian Scarfe
Henriques at dhenr...@earthlink.net wrote on 1/27/01 14:55:
> What's the down side on pulling the mixture to idle cutoff?
> 1. Shock cooling
That's a long term issue, and I'm not convinced that the shock cooling
associated with mixture at ICO is very much more serious than a sudden
change to a closed throttle. Neither is kind!
> 2. Broken mixture cable
> 3. Fuel related problems on restart
> 5 Unforeseen engine component failure that denies restart
Is the risk associated with these so much higher than with the engine
turning? Perhaps...
> 4. Broken starter
I'd add 4a. Not enough voltage in the electrical system to turn the prop.
I've never tried it but anecdotal evidence leads me to believe that the prop
will not stop unless you let the airspeed fall well below best glide speed
in most simple singles. (Is that consistent with others' experience?)
While I realise that the original debate was about stopping the prop, what
intrigues me is how the odds would change if you pulled the mixture but did
*not* stop the prop. That would take away much of the uncertainty that is
associated with getting it turning again.
One advantage that would seem to have is to reduce the vulnerability to
induction icing. If there's no fuel going through the induction system, the
latent heat of its vaporisation doesn't contribute to the cooling, and the
carb temperature is likely to be higher than with the same engine running at
normal idle. I'm sure carb heat is selected before engine failure
simulations, but just how effective is it in a prolonged descent?
A final comment: there's a risk vs instructional-benefit balance here, and
that applies to twins as well as singles. The FAA presumably believes that
this balance falls toward the benefit side in making sure that the pilots of
light twins *do* have experience of a real engine shutdown and restart. It
would, after all, be perfectly possible to train for the multi rating
without ever stopping a prop, and simulating zero thrust every time. It
would be hard to argue that the risk associated with being left with one
engine in a twin at 3000 ft is anything like as great as that of being left
with no engine in a single at 500 ft, even above an airport. But the
difference is one of degree rather than principle.
Julian Scarfe
highflyer
Back when I learned to fly, we were taught to run each tank dry. Now
they want you to have some fuel left in all tanks. I don't know which
is best, but I DO know, that when I am down to my last ten gallons or
so, I would rather have all of it in one tank that to have a couple
of gallons or so in each tank. I only know one way to achieve that
result.
Which is less likely to turn into a real emergency from a simulated
emergency. Stopping the engine by pulling the mixture to idle cutoff,
or simple retarding the throttle to idle? I am not sure, myself. I
have seen more simulated engine failures turn into real engine
failures by pulling it to idle than by pulling the mixture. Admittedly
either procedure could result in an engine that you can't readily get
back.
As for stopping the prop, with most airplanes I have flown that is NOT
an easy thing to do. A big engine with a wooden prop perhaps. Most
will keep windmilling nicely unless you really make an effort to get
the prop stopped.
Most engines will come back on line promptly and smoothly when the
mixture is pushed back in. You will NOT load up the cylinders with
unburned fuel or wet the plugs with the mixture in idle cutoff.
In a real emergency, you do have to deal with the shock. Best to
know that you CAN deal with it. Doing trick to keep the student in
a state of nervousness waiting for something bad to happen is, I agree,
counterproductive. Giving the student the confidence to deal with
any mishap that could arise can be lifesaving.
I have had engines quit on me a number of times. Never, because of
fuel exhaustion, however. Only once did the prop stop and it was a
newly overhauled and very tight engine with a wooden prop with a
very low rotational inertia. Unfortunately, that particular airplane
didn't have an electrical system, so it didn't have a starter. Even
diving at Vne wouldn't get it turning again. I landed! :-) At an
airport! :-)
What is best? Pulling throttle or pulling mixture? Current FAA
thinking says pull the throttle and be sure to clear it on the way
down.
The important thing, as Dudley said, is to learn how to establish
glide, how to determine where you can go, and learn to glide to a
key position like you use in a normal landing. Then the engine
out emergency is converted into a normal power off landing. :-)
I also teach folks to kind of evaluate the terrain you are flying
over, picking out the best emergency landing areas as you are flying.
Then, if your engine should ever quit, you already have the hard
part done! :-)
Of course, I also teach minor diversion on cross country trips to
allow you to pass over airports along the way. Not only do airports
make great checkpoints, but if things go wrong, you KNOW where there
is an airport nearby, and what it looks like, and can go back there.
When the weather gets marginal, it is always nice to know exactly
where you can retreat safely. Many times I have landed, had a coke,
used the facilities, and relaxed a few minutes while a front moved
over. Then I could go out, take off and fly on in the relatively
clear weather behind the front. It is much more comfortable than
flying through them! :-)
--
HighFlyer
Highflight Aviation Services
ags...@my-deja.com
"Dudley Henriques" <dhenr...@earthlink.net> wrote:
Hey Dudley,
Could you clear up a few items for me?
I'm watching both viewpoints on this discussion, and have yet to make my
own conclusions.
I know I would learn something about my aircraft and myself by
experiencing an actual shutdown in the air, but I am also concerned
about hurting the aircraft (especially since it's not a rental).
> What's the down side on pulling the mixture to idle cutoff?
> 1. Shock cooling
I can see how this is a factor if the instructor does it quickly, but
what if I slow down the plane, eventually get it into slowflight, then
idle the engine for a bit before pulling the mixture.
Won't I avoid this issue?
> 2. Broken mixture cable
I know I'm probably missing something important, but I don't understand
how a broken mixture cable is a hazard of shutting down the plane
inflight? Is it more likely to break in the air than it is on shutdown
on the ground?
Thanks for sharing your opinions. You are highly respected by me, and I
appreciate you sharing your ideas here.
flyi...@my-deja.com
Julian Scarfe <julian...@innoviatech.com> wrote:
> in article zjBc6.4867$OR1.5...@newsread2.prod.itd.earthlink.net,
Dudley
> Henriques at dhenr...@earthlink.net wrote on 1/27/01 14:55:
>
> > What's the down side on pulling the mixture to idle cutoff?
> > 1. Shock cooling
>
> That's a long term issue, and I'm not convinced that the shock cooling
> associated with mixture at ICO is very much more serious than a sudden
> change to a closed throttle. Neither is kind!
Julian
That is a very readable post and I pretty much agree about the shock
cooling. When I was pulling jumpers over the years, I always carried
power to keep temps up in the engines while I unwound from altitude. As
for induction icing, on several occasions I have used the primer to
keep the engine running while developing heat to make carb heat
effective again.
A few times I was really surprised at fuel exhaustion due to mechanical
malfunctions both in airplanes and helicopters. Only once did I have an
engine quit as a result of intentionally running to the end of my fuel
range but it worked out OK and I made the airport. Beat hell out of
landing in the jungle full of nasty people.
Things do break at the most inopportune time. I recall once pulling the
throttle back on a Bellanca Viking and it came all the way out in my
hand! Bellanca said it could not happen and later I got a call from the
President of the company with an apology after it happened to him as
well on short final!
Those who are never taught how to react with emergencies of a wide
variety are being cheated. Those of us with a lot of experience I feel
are obligated to pass along that experience. That, I feel is an unspoken
statement on my CFI certificate. How we achieve that goal is the thrust
of the argument here.
I have enjoyed nearly all the postulations even if I disagreed with
some of them. I hope you continue to contribute your experience and
thoughts.
Best Regards
FlyinRock
mike regish
>
> > 2. Broken mixture cable
>
> I know I'm probably missing something important, but I don't understand
> how a broken mixture cable is a hazard of shutting down the plane
> inflight? Is it more likely to break in the air than it is on shutdown
> on the ground?
>
It's a hazard if it breaks when you pull the mixture. You won't get a
restart.
--
mike regish
1953 TriPacer
N3428A
jga...@hotmail.com
Wouldn't the identical "hazard" exist with the throttle cable? It's
unlikely that either will suddenly break, but if they do, you're in the
same boat no matter which control you used.
John Galban=====>N4BQ (PA28-180)
Dudley Henriques
<ags...@my-deja.com> wrote in message news:954mcm$gj5$1...@nnrp1.deja.com...
> In article <zjBc6.4867$OR1.5...@newsread2.prod.itd.earthlink.net>,
> "Dudley Henriques" <dhenr...@earthlink.net> wrote:
> Hey Dudley,
> Could you clear up a few items for me?
Thank you for your question and I'll try and answer it for you.
>
> I'm watching both viewpoints on this discussion, and have yet to make my
> own conclusions.
> I know I would learn something about my aircraft and myself by
> experiencing an actual shutdown in the air, but I am also concerned
> about hurting the aircraft (especially since it's not a rental).
>
>
> > What's the down side on pulling the mixture to idle cutoff?
> > 1. Shock cooling
>
> I can see how this is a factor if the instructor does it quickly, but
> what if I slow down the plane, eventually get it into slowflight, then
> idle the engine for a bit before pulling the mixture.
> Won't I avoid this issue?
Perhaps; perhaps not; but the mechanics involved isn't the real issue here.
The issue deals with whether or not the entire procedure is necessary or
even advisable as a teaching tool.[see end of post for recap]
> > 2. Broken mixture cable
>
> I know I'm probably missing something important, but I don't understand
> how a broken mixture cable is a hazard of shutting down the plane
> inflight? Is it more likely to break in the air than it is on shutdown
> on the ground?
Think about this for a moment. If it breaks when you pull it, how are you
going to use it to start the engine again? And no, it's not more suceptible
to breakage in the air than on the ground. The difference is that on the
ground you are not faced with a forced landing you might have avoided by not
pulling it in the first place. Again we arrive at the good judgement call.
If an instructor couldn't teach a student about emergency procedure and
engine failure without pulling mixture and stopping the prop, I'd be the
first one up there doing it. See the end of this post as to why this isn't
necessary.
> Thanks for sharing your opinions. You are highly respected by me, and I
> appreciate you sharing your ideas here.
Thank you.
Please understand that in discussing this issue, I place the actual
mechanical problems that COULD occur way behind the issue of whether or not
this procedure is generally considered in the flight instruction community
to be one where a POSSIBLE RISK can be avoided and the lesson objective
achieved by far better means available. I believe I have stated exactly how
this can be done in prior posts. Hell, if I thought, and the majority of
flight instructors out there felt, that the only way to properly prepare a
student pilot for an engine failure was to stop the engine cold and stand
the prop dead on it's shaft; I'd be the first to be advocating this
procedure. The plain hard fact is that we discovered long ago that this
procedure was INFERIOR to other procedures in preparing pilots to handle
emergencies in the air. That's why we don't do it. There is a risk factor
present in all aspects of flying. Certain risk you accept. You avoid risk
that can be classified as unnecessary for the mission. That's where pulling
the mixture falls. Not only is it a risk that can be avoided, but it is also
a procedure that is inferior as a lesson to other means of teaching and
achieving the lesson goal.
Re-read if you will, my complete explanation on why this procedure isn't
necessary. It's at the end of the post.
You can hash this all over the place with whether or not the engine will
actually quit; whether or not the cable will break; whether or not shock
cooling can be controlled by slowing down the airplane before pulling the
mixture.....all this is fine and good, but remember, we are discussing a
risk that can be avoided by using a better procedure that achieves a BETTER
goal for the same lesson problem.
Recap:
Perhaps I should have worded my initial post a bit differently, as it seemes
to have surfaced an angry response by someone saying that to NOT do this
procedure is to short change the student.
Let me put it another way now.
It's a matter of choice whether or not an instructor pulls mixture to idle
cutoff and slows the airplane down to stop the propeller on a student. I
don't do this EVER! No instructor working for, or with me does this EVER! No
FBO that is associated with me now or has ever been associated with me has
allowed this in their airplanes; EVER! I know of no competent manual dealing
with flight instruction that recommends this procedure. I know of no engine
manufacturer who will recommend this procedure. I know of no competent
governing authority in the United States dealing with general aviation that
will recommend this procedure, and in fact in many cases will specifically
recommend against it.
I firmly believe that a competent student can be turned out without doing
this, and I also believe that if pilots do a little research themselves,
they will discover that what I have described as being the accepted norm in
the instructional community is indeed that, and that it's NOT a normal
procedure for a flight instructor to do this with a student; and that
students are being turned out just fine without placing them and the
airplane at risk with this quite unnecessary procedure.
BARR DOUG
go full rich on cable breaking. this is due to springs.
In article <9551v7$rh4$1...@nnrp1.deja.com>, <jga...@hotmail.com> wrote:
>In article <3A75F3AD...@mediaone.net>,
> mike regish <mre...@mediaone.net> wrote:
>> ags...@my-deja.com wrote:
>>
>> >
>> > > 2. Broken mixture cable
>> >
>> > I know I'm probably missing something important, but I don't
>understand
>> > how a broken mixture cable is a hazard of shutting down the plane
>> > inflight? Is it more likely to break in the air than it is on
>shutdown
>> > on the ground?
>> >
>>
highflyer
>
> In article <zjBc6.4867$OR1.5...@newsread2.prod.itd.earthlink.net>,
> "Dudley Henriques" <dhenr...@earthlink.net> wrote:
>
> Hey Dudley,
> Could you clear up a few items for me?
>
> I'm watching both viewpoints on this discussion, and have yet to make my
> own conclusions.
> I know I would learn something about my aircraft and myself by
> experiencing an actual shutdown in the air, but I am also concerned
> about hurting the aircraft (especially since it's not a rental).
>
> > What's the down side on pulling the mixture to idle cutoff?
> > 1. Shock cooling
>
> I can see how this is a factor if the instructor does it quickly, but
> what if I slow down the plane, eventually get it into slowflight, then
> idle the engine for a bit before pulling the mixture.
> Won't I avoid this issue?
>
> > 2. Broken mixture cable
>
> I know I'm probably missing something important, but I don't understand
> how a broken mixture cable is a hazard of shutting down the plane
> inflight? Is it more likely to break in the air than it is on shutdown
> on the ground?
>
Interestingly, and not statistically significant, but in all of my
flying
I have never had a mixture control break. I have twice over the years
had the Carb Heat control come out in my hand, and once I did have the
throttle cable come disconnected.
With the throttle cable I was in the pattern, so I merely went around
and landed.
With the carb heat control, once it happened during the runup. No
problem.
The other time it happened in flight when carb icing was encountered.
I found that I could melt the ice by going to full power and slow
flying behind the power curve. The combination of full power and low
speed created enough heat in the induction system to melt the ice.
Julian Scarfe
news:3A76EE94...@alt.net...
> Interestingly, and not statistically significant, but in all of my
> flying
> I have never had a mixture control break. I have twice over the years
> had the Carb Heat control come out in my hand, and once I did have the
> throttle cable come disconnected.
Reminds me of the local pilot who was flying an Aztec. The Aztec has
conventional hydraulics for gear lowering, you just select gear down. If
the pump fails, you select gear down, and use the hand pump. If that fails,
you select gear down and use the gas bottle under the pilot's seat. What
could go wrong?
On raising the gear after take-off, the gear selector came off in his hand,
with the selector in the up position...
Julian Scarfe
Ron Natalie
Julian Scarfe wrote:
>
> On raising the gear after take-off, the gear selector came off in his hand,
> with the selector in the up position...
The Aztec obviously needs the Navion solution. The emergency gear mechanism
is just another (bigger) handle.
gross_arrow
Julian Scarfe <julian...@innoviatech.com> wrote:
> While I realise that the original debate was about stopping the prop,
what
> intrigues me is how the odds would change if you pulled the mixture
but did
> *not* stop the prop. That would take away much of the uncertainty
that is
> associated with getting it turning again.
>
> One advantage that would seem to have is to reduce the vulnerability
to
> induction icing. If there's no fuel going through the induction
system, the
> latent heat of its vaporisation doesn't contribute to the cooling, and
the
> carb temperature is likely to be higher than with the same engine
running at
> normal idle. I'm sure carb heat is selected before engine failure
> simulations, but just how effective is it in a prolonged descent?
>
>
> Julian Scarfe
>
It is because of this perceived reduction in succeptibility to carb
icing that
I began pulling the mixture control instead of the prop when training
for
engine outs with students. (Let me categorically state that I _never_
stopped
the prop). The line of reasoning, argued on one of these forums, was
that
all you need is spark, compression, fuel, and rotation for the engine to
run.
Pulling the mixture instead of the throttle merely removes the fuel.
Restoration
of the fuel results in instantaneous restoration of power -- even more
so
than the throttle method (which frequently results in a sputter or two
before
power is restored, presumably because of induction icing, or plug
fouling,
or whatever). In the past 3 or 4 years I have used this technique, I
have
never failed to have power restored instantly upon pushing the mixture
back
in -- until recently, that is.
I was training a 'transfer' student. This guy had 16-18 hours, was a
pretty good
stick, but hadn't flown in 7-8 years, and now wanted to finish up. We
went through
the engine out drill on the ground, using a '5-F' mnemonic I developed
some
years ago when I first began instructing:
1. Fly -- Fly the airplane. Trim to best glide, etc.
2. Field -- Pick your emergency landing field and head towards it.
3. Fix -- Check fuel, carb heat, mixture, etc, and attempt restart.
4. Frequency -- 7700 on xpndr, 121.5 on comm, m'aidez call, etc.
4. Final -- fuel & electrics off, seatbelts secured, door unlatched,
etc.
We took off & climbed to about 2000 AGL, and I pulled the mixture on
him. He
set up best glide, then started to do the troubleshooting. Now, I have
on occassion
let a student screw up and get this out of sequence, resulting in a good
object
lesson for the student when we run out of altitude and are not in
position to land
anywhere remotely desirable. But for some reason, this time I corrected
the student
and insisted that he pick his field & head towards it. Good thing, too,
because
at about 150 AGL when I pushed the mixture back in, power was _not_
restored.
The engine ran very roughly and did not produce enough power to maintain
altitude, so we landed in the field. Classic carb ice symptoms. After
landing,
the engine started normally and developed full power.
We taxied back to the edge of the field and started a takeoff roll.
Unfortunately,
there had been a lot of rain lately, and at about 35 mph we hit standing
water, and
could not overcome the additional drag. When I pulled the throttle
because the
end of the field was coming up, the nose gear got stuck in the mud. The
field
belonged to some doctor, and his caretaker gave us a ride back to the
airport
where we picked up some boards and additional manpower. Back to the
field,
we walked over it to find the dryest area, the freed the 150 from the
muck, and
I was able to takeoff and return to the airport without further
incident.
So, I thought I was hedging against carb ice by using the mixture
instead of the
throttle, but I got carb ice anyway this time. I am now undecided about
the
relative merits -- I still think the arguments favor pulling the mixutre
(but _not_
stopping the prop, I hasten to add), but the last coupla times I've done
engine
out training, I have to admit that I used the throttle (and got the
attendant
'sputter' when first pushing it back in). I have decided to _always_
make sure
the student has a landable field in range before proceding too far with
the
exercise. You never know when you might have to put it down.
G.A.
Jeffrey Osier-Mixon
> with the selector in the up position...
So what happened?!
flyi...@my-deja.com
"Julian Scarfe" <jul...@avbrief.com> wrote:
> "highflyer" <high...@alt.net> wrote in message
> news:3A76EE94...@alt.net...
that brings to mind a young instructor who reached down to shut off the
fuel in a C-150. The selector came off in his hand. Well, no big deal
and he handed it to his student to let him know the problem. when they
spiraled down over a wheat field for an emergency landing scenario, the
young CFI asked him to put the fuel selector back in place but the
student had dropped it out the window! They ended up making an
uneventful landing in the wheat field. Why did he drop it out the
window? He was cracking the door open to avoid a stuck door in the
event of a hard landing. In his excitement, he had opened the window
instead of the door! High wings will certainly jam doors shut if they
collapse.
Here is another point for some flammable posts I am sure. But, having
experienced it, I will certainly pass along every kind of experience I
can to any students I fly with.
Another time I was flying with a 727 pilot who had bought a float plane
and prepped him for his float rating. When I did a variety of emergency
procedures, it was interesting for both of us as he reached for
overhead controls or panel controls that are in the 727 but certainly
not in his float plane. We discussed that at length after the flight
training. As I have said repeatedly, there are many ways to handle an
emergency, and many ways of teaching it. Some of what is taught is
such "Pablum" that a pilot will come unglued in a real emergency. When
I was instructing with FlightSafety I several times did unexpected
things during emergency procedures outside the published curriculum,
things that I had experienced, that caused the "trainee" pilots to
wonder what was going on and in the process, forgot their primary duty
was to fly the damned airplane until the dust settles. It made for
interesting conversation afterwards.
Best Pro Regards
FlyinRock
flyi...@my-deja.com
Ron
does that mean if the brakes fail you just press harder on the pedals?
<ggg>
I've given lots of dual in both the Aztec and Navion and enjoy both of
them. In fact, years ago I was an AOPA refresher clinic pilot doing the
Aztecs, Navions, and Bonanzas for IFR refreshers.
Ron Natalie
flyi...@my-deja.com wrote:
> does that mean if the brakes fail you just press harder on the pedals?
Pressing on the pedals? Not in a stock Navion. It's yet another handle.
For those who don't get what I'm talking about, the Navion gear handle
is a big lever that sticks out of the panel about 4". It works not only
a hydraulic valve but also a cable that releases the uplock. When hydraulic
power is present, and the handle is up, the gear actually is lifted off the
uplocks giving enough leverage in the handle to move the locks.
If the hydraulics fail, there isn't enough leverage to pull the locks with
the gear resting on them. The emergency extension handle is literally,
just a longer lever on the uplock release. Once the locks are released
the gear slams down by gravity.
An amusing story, Margy was doing her BFR in an Arrow because the
Navion was in the shop. After taking off, she was hunting around for the
gear lever. After the instructor pointed out the tiny toggle switch, margy
flicked it with two fingers saying "This little thing? How cute!"
The Navion gear handle takes your entire hand to pull and lift (plus
you have to hit the secondary safety under the panel with your little
finger).
adam
gross_arrow <gross...@my-deja.com> wrote in message
news:957a1n$ove$1...@nnrp1.deja.com...
nice post this is one of those quality posts that prompts food for thought !
G.A., reading your post prompted me to remember something my instructor did
when I was going through my PPL in the UK. When I was going through the
simulated engine failure, at intervals (every 500ft) he would open it up a
little for a second or so to confirm that the power was available when
needed and thus give more time to establish an actual failure from a
simulated. Another benefit was that it reduced the shock cooling
characteristics.
he also got me in the habit of doing likewise
anyone else experienced this during training ?
robert a.barker
food for thought !
>
> G.A., reading your post prompted me to remember something my instructor
did
> when I was going through my PPL in the UK. When I was going through the
> simulated engine failure, at intervals (every 500ft) he would open it up
a
> little for a second or so to confirm that the power was available when
> needed and thus give more time to establish an actual failure from a
> simulated. Another benefit was that it reduced the shock cooling
> characteristics.
>
> he also got me in the habit of doing likewise
>
> anyone else experienced this during training ?
Yes my instructor always gave a few short bursts of
power duryng my glide.He said it was for the same reason as you state.
Bob Barker PP-ASEL
StellaStar
>I found that I could melt the ice by going to full power and slow
>flying behind the power curve.
What an example of great thinking that could help us all some day. This is the
kind of thing that sets me pondering, and making the connections that will make
me a better, more versatile pilot.
Talking of things that bust off when pulled, I was going up in a 172 one day
in December and my flying partner went to start her up when the primer assembly
came out in his hand. Knob, stick, and the little tube it slides through, as
well as the bolt that holds it to the dash. We looked at each other, then
stared at the primer hole waiting for a flood of fuel to pour out onto his foot
and blow us both up.
One drop came out. He tried to stuff the primer back into the panel, and
then we both got out quick.
The chief mechanic was a few steps away in the next hangar, and assured us
we weren't about to empty the tanks into the cockpit. He re-secured the primer
assembly, but broke a mike wire off behind the panel with his wrench in the
process. We took another plane.
I've flown that 172, after another mechanic did more extensive repairs to
the primer knob.
Richard Tilton
gross_arrow wrote:
> ...
> at about 150 AGL when I pushed the mixture back in, power was _not_
> restored.
> The engine ran very roughly and did not produce enough power to maintain
> altitude, so we landed in the field. Classic carb ice symptoms. After
> landing,
> the engine started normally and developed full power.
> ...
This is precisely why I tend to agree with Dudley on this issue. Why ruin
your whole day in the name of more realistic training, when the proper
HABITS can be established with the engine at idle. Even though the
performance may be slightly different with the engine off, you still must
fly the plane given it's current performance. This is true whether you are
dealing with an inflight emergency, a high density altitude take-off or
crosswind landing. Fly the plane.
Richard
Dylan Smith
<julian...@innoviatech.com> wrote:
>I've never tried it but anecdotal evidence leads me to believe that the prop
>will not stop unless you let the airspeed fall well below best glide speed
>in most simple singles. (Is that consistent with others' experience?)
In our Cessna 140, (C-85 engine, metal Macaulay prop) you have to be
on the ragged edge of a stall to stop the prop. To get it started again,
you have to dive into the yellow arc (about 120 mph).
--
Dylan Smith, Houston, TX
Flying: http://www.alioth.net/flying
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"
zipperhead
>nice post this is one of those quality posts that prompts food for thought
!
>G.A., reading your post prompted me to remember something my instructor did
>when I was going through my PPL in the UK. When I was going through the
>simulated engine failure, at intervals (every 500ft) he would open it up a
>little for a second or so to confirm that the power was available when
>needed and thus give more time to establish an actual failure from a
>simulated. Another benefit was that it reduced the shock cooling
>characteristics.
>
>he also got me in the habit of doing likewise
>
>anyone else experienced this during training ?
up here in canada it is an automatic fail on your flight tests if you do not
open the engine up every time you hit the key position .. reason .. who
needs a real engine failure when simulating one .. i remember reading about
an accident once that was fairly recent in which the instructor and student
couldn't get enough power out of the engine while practicing the forced
landing (for just that reason) and i think there was fatalities ..
highflyer
< good stuff snipped >
> So, I thought I was hedging against carb ice by using the mixture
> instead of the
> throttle, but I got carb ice anyway this time. I am now undecided about
> the
> relative merits -- I still think the arguments favor pulling the mixutre
> (but _not_
> stopping the prop, I hasten to add), but the last coupla times I've done
> engine
> out training, I have to admit that I used the throttle (and got the
> attendant
> 'sputter' when first pushing it back in). I have decided to _always_
> make sure
> the student has a landable field in range before proceding too far with
> the
> exercise. You never know when you might have to put it down.
>
While removeing the fuel from the induction system also removes the
temperature drop caused by the vaporization of the fuel, and thereby
removes one of the leading contributors to carb icing, you may still
have a fair pressure drop across the throttle plate. This pressure
drop also lowers the temperature. When conditions are just right,
you can get carb ice either way. Just less likely with no fuel being
vaporized! :-)
The solution, and you hit it, is to NEVER give an engine out simulation
in a place where you cannot safely land the airplane! You never know
when you will have to do so, no matter HOW you simulate the engine out!
I would be very reluctant to allow the student to continue toward an
unlandable field! At least not beyond where I could make it to a
landable field if it failed to go again.
In my experience, I have found that you are more likely to regain full
power on demand when you pull mixture than when you pull throttle.
Unfortunately, with either technique, sometimes you cannot recover
full power on demand.
Take it for what it is worth. I don't know everything. Quite! :-)
Julian Scarfe
news:3A773649...@transmeta.com...
He managed to find a screwdriver, forced it though the panel, and eventually
managed to push the gear switch down. I just think it's an interesting
anecdote for those interested in failure mode analysis...
Julian
Alun
writes
OK, guys. What would be the normal procedure if the throttle jammed at
full power? Apart from total panic in my case?
--
Alun
HLAviation
>full power? Apart from total panic in my case?
Simple, fly to the field of your choice, and shut off the mags and glide. You
can then control the glide path by switching mags on and off. This is exactly
the technique used when flying a plane with a rotary engine (Rhone type, not
Wankel) since these engines don't have throttles.
Roy Smith, CFI
This is a drill I run with students every so often, except that I add a
twist...
You are at 3500 when the throttle goes full open. The airport you need to
reach is VFR, with a 1500 ceiling. You are flying towards the edge of the
cloud layer, and need to loose 2500 or so feet to duck under it. You're
too far from the airport to just cut the engine and glide, so how are you
going to get down without exceeding any Vspeeds?
I usually let the student flounder around a bit and then start suggesting
things like carb heat on to get rid of some power, and running on a single
mag to get rid of a bit more (although lately I've come to understand that
this may be bad for exhaust valves, which doesn't bother me in a real
emergency, but isn't something you want to do in a practice drill).
Usually, a steep climb will get you under Vfe, and then once you've got
full flaps extended, you can usually maintain below Vfe in a reasonable
descent with full power and a steep slip.
It's a fun exercise.
--
Roy Smith, CFI-ASE-IA
Rod Farlee
>> It's a hazard if it breaks when you pull the mixture. You won't get a
>> restart.
>unlikely that either will suddenly break, but if they do, you're in the
>same boat no matter which control you used.
The Marvel-Shebler carbs (MA-4, MA-5) on nearly all small planes
have a spring on the back top of the carb which immediately pushes
the mixture full rich if the cable were to break.
There is no such spring on the throttle.
p.s. The most (by far) experienced flight instructor in my state pulled
the mixture on me, when he thought I was getting too low on final
in a simulated emergency landing.
I definitely think he was right to do so. He made his point!
- Rod Farlee