MEI books

When I went through ATP the DPEs were always careful with Vmc demos. They would block part of the rudder... like prevent you from pushing the rudder all the way down, this would artificially raise Vmc since you had less rudder authority.

It made sense, I mean otherwise you'd just get the horn first in the seminole. They wanted you to see the actual lose of directional control.
 
SpiraMirabilis said:
When I went through ATP the DPEs were always careful with Vmc demos. They would block part of the rudder... like prevent you from pushing the rudder all the way down, this would artificially raise Vmc since you had less rudder authority.

It made sense, I mean otherwise you'd just get the horn first in the seminole. They wanted you to see the actual lose of directional control.
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They shouldn't do this, as the PTS states that you must be using full rudder, but oh well.
 
SpiraMirabilis said:
When I went through ATP the DPEs were always careful with Vmc demos. They would block part of the rudder... like prevent you from pushing the rudder all the way down, this would artificially raise Vmc since you had less rudder authority.

It made sense, I mean otherwise you'd just get the horn first in the seminole. They wanted you to see the actual lose of directional control.
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My MEI was both a checkride and a learning experience (almost like an apprenticeship). The DE had thousands of hours of DC-3 time along with a ton of corp aircraft including king airs. It was both a teaching and learning experience...

On my MEI we did the VMC demo as per the PTS and I agree with mojo. However after, the DE showed me a real VMC that wasn't part of the checkride. PA-34, dropped the gear and dumped the flaps then he demonstrated a *real* VMC situation (simulated single engine app but at 4000ft). The PA-34 doesn't roll over, just yaws heavily/uncontrollably. Interesting to take the airplane into a full VMC situation and see the outcome and what it takes to recover vs. take the airplane to almost pwr on stall config, reduce power, recover, etc...

As for books I just studied the AFM until I knew the systems and limitations down cold, then looked over my syllabus for the multi, looked over the ASA AMEL oral guide, and the Airplane Flying Handbook. All of that gave me enough info and more...
 
mojo6911 said:
They shouldn't do this, as the PTS states that you must be using full rudder, but oh well.
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The FAA made moves to forbid this a few years ago, but the DPE's rebelled and the FAA backed down. I agree with the DPE's position. From the candidate's perspective it IS full rudder; the fact that it's artificially full is irrelevant.
 
Agreed, from your perspective as the pilot it is full rudder. You press and it doesn't go back any farther. Especially on twins like the Seminole, Duchess, 310.. if you dont do this youre ALWAYS going to have first indications of a stall (buffet, horn, etc) before loss of directional control because they usually start like 5-10kts above stall speed.
 
jdlilfan said:
Interesting to take the airplane into a full VMC situation
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He could lose his designation for something like that; it's the sort of thing that has gotten examiners and candidates killed in years gone by. The Vmc demo is the way it is for a good reason.
 
I've written it once, I'll write it again. The Vmc demo is probably the most dangerous manuever you will do as a CFI. If it gets away from you and turns into a spin you may very well be out of luck. I knew a test pilot killed doing Vmc testing in an Army cargo turbo prop. Don't press it. Do what is in the PTS. I'm with T on this one.
 
Blackhawk said:
I've written it once, I'll write it again. The Vmc demo is probably the most dangerous manuever you will do as a CFI. If it gets away from you and turns into a spin you may very well be out of luck. I knew a test pilot killed doing Vmc testing in an Army cargo turbo prop. Don't press it. Do what is in the PTS. I'm with T on this one.
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I fully agree that it is very dangerous, and I take it seriously, however the PTS does say:

Increases the pitch attitude slowly to reduce the airspeed at
approximately 1 knot per second while applying rudder pressure
to maintain directional control until full rudder is applied.
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Now, I have to teach it this way and IMO, it should be examined this way. We have the PTS to standardize the training, so when rogue DPEs take it upon themselves to change the standards, it screws up the whole system.

If they want to artificially limit the rudder, ok. I don't necessarily agree with it, but I am still going to teach them to apply full rudder for the demo. Since this is usually an initial multi-engine license, I feel I would be doing them a disservice to artificially limit the controls of the airplane. To me, its like telling a student pilot to never do a full stall recovery, but to recover when the stall warning horn goes off, well before the stall.
 
Page 12-30 of the AFH states:

"An actual demonstration of Vmc may not be possible under certain conditions of density altitude, or with airplanes whose Vmc is equal or less than Vs. Under those circumstances, as a training technique, a demonstration of Vmc may be safely conducted by artificially limiting rudder travel to simulate maximum available rudder. Limiting rudder travel should be accomplished at a speed well above Vs (approximately 20 knots)."
 
depends on my mood, but usually i limit ailerons and not rudder becuase even in the Seminole there comes a point where the rudder won't do it if you don't use ailerons as well and you will loose directional control. now granted that point is probably 5kts or less away from the stall indications.......

and there is a relationship between VMC and Stall. in one area you will loose directional control first, in one area you will stall first, and in the 3rd area they will both happen at the same time.....
 
BuickCFI said:
depends on my mood, but usually i limit ailerons and not rudder because even in the Seminole there comes a point where the rudder won't do it if you don't use ailerons as well and you will loose directional control. now granted that point is probably 5kts or less away from the stall indications.......

and there is a relationship between Vmc and Stall. in one area you will loose directional control first, in one area you will stall first, and in the 3rd area they will both happen at the same time.....
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Putting in or taking out ailerons (bank) increases or decreases Vmc only because it provides stability to the aircraft, the greater the bank the more stability and less performance. We use 1/2 a ball out because it provides the best combination of stability and performance. So your not changing Vmc, it is still 56, you are only giving less favorable conditions which causes Vmc to be higher then it in fact is. Consider this:

"(a) VMC is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane with that engine still inoperative, and thereafter maintain straight flight at the same speed with an angle of bank of not more than 5 degrees. The method used to simulate critical engine failure must represent the most critical mode of powerplant failure expected in service with respect to controllability."

So if you are under 5 degrees of bank your Vmc will probably be above the published. Hopefully everyone here is in agreement that bank angle has the greatest effect on Vmc because I really don't want to draw a vector diagram!

Vmc is any point where any control surface reaches its maximum deflection for the given configuration. If you change the configuration (ie bank in your case) then Vmc will be different for that new configuration. As was pointed out earlier it tends to be rudders in light twins that is restrictive, in my experience in the Seminole this is true and from what I hear this holds true for most all light twins.

There is no relationship between Vmc and stall. There are certain configurations which will yield a stall before Vmc which in the Seminole with only a 1 knot difference I would bet this is negligible. There are also other configurations which will yield a higher Vmc which will yield Vmc before stall. Just because different configurations yield different results doesn't mean Vs and Vmc are related.

In my opinion the student simply needs to know the factors that effect Vmc and that Vmc is decided with the least favorable conditions. Knowing that you see the Seminole is at 56 which is already under stall in the least favorable conditions so chances are any condition your in will yield a lower Vmc then published. The largest factor is properly flying the aircraft 1/2 ball with 3-5 degrees into the good engine, if they fly that (at least in the Seminole) you stall before Vmc is reached. Explain why we fly like this showing the forces and also explain zero side-slip (so they know their options) and the exchange of control/performance. If a student can understand all that I can't imagine them needing to know anything else about multi engine flying, from that point on it is can they apply it.
 
tgrayson said:
Er, that's called Vmc. You shouldn't put in any more aileron once you're out of rudder.
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right, and that is what i do, i limit them to around 5 degrees of bank so they can see what it means to lose directional control. because of all the multi students i have taught (maybe 15 or 20) if i try to limit the rudder they just fight me because they know it goes farther.
 
There is no relationship between Vmc and stall. There are certain configurations which will yield a stall before Vmc which in the Seminole with only a 1 knot difference I would bet this is negligible. There are also other configurations which will yield a higher Vmc which will yield Vmc before stall. Just because different configurations yield different results doesn't mean Vs and Vmc are related.
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right, but i may teach in a seminole, but i don't teach only the seminole, there are many other airplanes out there that don't have a 1kt difference. so if you understand the factors, that is fine but since it Vmca is always changing and you can't calculate it, you need to understand those 3 areas. the biggest thing to know is how to identify in a timely manner and correct before anything happens. so i feel there is a relationship between Vmc and Stall, granted there is no mathmatical relationship, but there is a point where they will BOTH happen at the SAME time, and that is a relationship.
 
tgrayson said:
He could lose his designation for something like that; it's the sort of thing that has gotten examiners and candidates killed in years gone by. The Vmc demo is the way it is for a good reason.
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I'm not saying I support it nor I am going to go out and do it or teach students that method, just thought I would share an interesting experience that could happen in real life. It wasn't part of the checkride, just something the DE wanted to demonstrate.
 
Plain and simple you just should not do a "real" Vmc demo unless your the test pilot for that aircraft and the little engineering nerd squad has done its 4 million calculations to make sure your specific configurations won't get you killed. At least that is what they do when they do flight testing for any aircraft for Vmc, computers verify the safety of every possible scenario and then the test pilot test it with very stringent specific standards.

The point is while in your PA-34 you didn't roll over this time that was only 1 configuration, weight, cg, and specific aircraft. All that could be completely different in an identical PA-34 loaded the same or differently so while you saw it work ok this time or some other applicant (you sound smarter then the typical) sees their DPE demo this and thinks oh man this plane won't roll over this is safe. He goes out shows it to all his students till one day something was just a little different the plane snaps over on its back and enters an inverted spin almost instantly. Being your typical CFI he has never seen an inverted spin (remember to enter this was a Vmc demo control stick almost all the way back) he/she freaks and lets go of the controls fall forward more raising the AOA (inverted) making the situation worse.

You can see where this is going, like I said in the beginning the PA-34 doesn't Vmc roll over in the conditions you saw, maybe it doesn't in most conditions, but someday in some condition . . . That is how dumb pilots kill themselves who have "done that demo 1000 times." There are reasons these demos are prohibeted and like many rules in aviation there are often numerous smoking holes that lead to the rule being developed.
 
shdw said:
Plain and simple you just should not do a "real" Vmc demo unless your the test pilot for that aircraft and the little engineering nerd squad has done its 4 million calculations to make sure your specific configurations won't get you killed.
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WHAT! I think it is EXTREAMLY important to see what it is really like to loose directional control. Some airplanes you will loose directional control well before the airplane ever stalls, unlike the seminole. And seeing how fast it actually happens definatly makes one raise an eyebrow. I think the reason that there are so many light twins crashing is because we train the way we do, in light twins that will stall before they loose directional control.


Now, do I agree with what was posted earlier with an actual VMC demo by a DPE, heck no! Do I agree with blocking a rudder pedal/aileron to see how fast it goes from "I got it" to "oh crap, I don't got it." Any one who has ever had it happen, real or otherwise knows how fast it happens. It is important to see it, and not just run through the motions that we were tought to recover i.e. "loss of directional control, first sign of a stall or saftey of flight."


Take your damn student out, and show them what it's like by blocking a control so they don't get accustemed to hearing the stall horn and recovering, else they might do that in a Metroliner, and roll it over on it's back, like you were talking about.

Bottom line, Directional control loss needs to be experinced in a safe, controled enviroment. But now that I re-read your post, I think that is what you have already said.:o
 
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