Vmc roll crash

[p1l07m4n]

I have to admit, I'm glad this video was posted. I have shown it to all of my multi-engine students. A great learning tool about the importance of maintaining a speed above VMC. Also, the importance of flying the airplane first, everything else second. Really helped them them out to determine their personal minimums for when to immediately feather an engine vs. trying to troubleshoot.

 

[Cass]

I have to admit, I'm glad this video was posted. I have shown it to all of my multi-engine students. A great learning tool about the importance of maintaining a speed above VMC. Also, the importance of flying the airplane first, everything else second. Really helped them them out to determine their personal minimums for when to immediately feather an engine vs. trying to troubleshoot.

That's what I like to hear, as awareness/education was my intent when posting. Of course any crash involving loss of live is a tragedy, and especially hard to watch, but there are a LOT of pilots out there (myself included) who have never seen a full roll. It's a sobering video.

 

[surreal1221]

Eek...reduce power on operative engine...

 

[Murdoughnut]

Is differential thrust every recommended for spin recovery in a twin? I've thought about it before, and it makes sense to increase thrust on the engine inside the spin, but I was wondering if their was any evidence that that helps.

 

[MikeD]

Haven't seen it as such in the twins Ive flown, but if nothing else is working, Im sure it wouldn't hurt to try. I mean.....you have the rest of your life to get out of the spin....or not.

 

[Pilotforhire587]

I think Bill Kershner is the only person to ever spin a seminole and live, took him something like 12000 feet to recover.

 

[SteveJeff]

In the book Aerodynamics for Naval Aviator it says that for each degree of bank angle towards the good engine your Vmc reduces by approximately 3 kts.

That is, banking towards inoperative engine, your Vmc might get pretty high, right?

Reading the thread and some VMC theory, I don't get it how VMC changes so much if you bank. I assume that is if you want to maintain straight and level flight, right and it doesn't apply if you want to turn. That is, if after takeoff, climbing at Vy, you are in a turn 30 degrees bank angle and your top engine failed, your VMC is likely above or at actual speed and thus resulting in an out of control scenario? You can't roll level using opposite aileron or you just can't maintain straight and level using that bank angle? I don't get it at all.

Other example, when your engine fails, you may not be able to arrest the initial roll, that means if the airplane rolls, let's say 20 degrees towards the dead engine, when it fails, your actual Vmc equals your actual speed considering this scenario after takeoff when you are usually about 20 kts above published Vmc. So, again you may lose control at all if the bank angle - Vmc relation is correct.

I also watched some videos where in single engine operation, light twins were banked normally during low and slow flight in single engine flying a normal traffic pattern. If so, they would lose control if VMC would be really increased when banking.

This theory also feeds the old never bank into dead engine rule. I'm not a ME rated pilot, but I hope will start my ME training soon, so at least I would like to be ready at least on the theory part of the issue which actually is the one which confuses me.

So what's the truth?

Thank so much!

 

[JayAre]

Lost our local DPE while doing multi check ride. I was the one who found the wreckage while doing an search for the overdue plane. If I wasn't on the phone I would link the NTSB report.

 

[rd757]

Never sacrifice control for performance. The common example is the engine crapping out 300 AGL, student sees the trees coming, starting pitching up to stretch it and spins it in short of the trees. I'd rather hit the trees in control, than auger it in and guarantee my demise.

A DPE I've heard of, does a Vmc roll with MEI applicants prior to their ride in the 'Nole. My good friend said the snap happens incredibly quickly, not that "oh no, the nose is 0.1˚ off to the left, time to reduce power." My good friend didn't take it all the way into a spin, since it's not approved for such maneuvers, but inverted in a 'Nole is not exactly a friendly place. "Control, roll" I believe is what the old-fella said to my good friend. Reduced the power on the good engine as soon as it rolled over, pitched the for the horizon (took a half second to figure out which way that was exactly), and rolled it back to the green side down. Recover as usual from that point...

My good friend said it was humbling to see what happens when you don't stay ahead of your students. Obviously, I would never take it that far with any of my students, but I think it's probably a valuable tool for MEI's to see before they start teaching others without ever having seen the danger themselves. I've heard horror stories of the twin Comanche, too.

 

[rd757]

In the book Aerodynamics for Naval Aviator it says that for each degree of bank angle towards the good engine your Vmc reduces by approximately 3 kts.

That is, banking towards inoperative engine, your Vmc might get pretty high, right?

Reading the thread and some VMC theory, I don't get it how VMC changes so much if you bank. I assume that is if you want to maintain straight and level flight, right and it doesn't apply if you want to turn. That is, if after takeoff, climbing at Vy, you are in a turn 30 degrees bank angle and your top engine failed, your VMC is likely above or at actual speed and thus resulting in an out of control scenario? You can't roll level using opposite aileron or you just can't maintain straight and level using that bank angle? I don't get it at all.

Other example, when your engine fails, you may not be able to arrest the initial roll, that means if the airplane rolls, let's say 20 degrees towards the dead engine, when it fails, your actual Vmc equals your actual speed considering this scenario after takeoff when you are usually about 20 kts above published Vmc. So, again you may lose control at all if the bank angle - Vmc relation is correct.

I also watched some videos where in single engine operation, light twins were banked normally during low and slow flight in single engine flying a normal traffic pattern. If so, they would lose control if VMC would be really increased when banking.

This theory also feeds the old never bank into dead engine rule. I'm not a ME rated pilot, but I hope will start my ME training soon, so at least I would like to be ready at least on the theory part of the issue which actually is the one which confuses me.

So what's the truth?

Thank so much!

Nope. Prior to my MEI ride, I did commercial steep turns into both the dead engine and into the good engine and it flew just fine. Maintaining altitude was a bit of a problem, but the whole myth "don't bank into the inop engine" is exactly that, a myth. It flies just fine and the wing doesn't know which engine is working or not. The yaw from the asymmetrical thrust is responsible for causing the eventual roll, not the "accelerated slip stream" from the prop wash on the operating engine. The problem lies in people getting slower than their blue line (Vyse) speed trying to stretch the 'glide' or clear an obstacle and it dips below the minimum controllable airspeed for OEI and the plane does exactly what the pilot asked it to do... but maybe not exactly what they wanted it to do.

Once again, never give up control for performance.

Edit: Double post, aw yeah.

 

[SteveJeff]

Nope. Prior to my MEI ride, I did commercial steep turns into both the dead engine and into the good engine and it flew just fine. Maintaining altitude was a bit of a problem, but the whole myth "don't bank into the inop engine" is exactly that, a myth. It flies just fine and the wing doesn't know which engine is working or not.

Same thing I knew, but if so, it's confusing, how does it come the explanation that VMC changes with bank angle? If there is a difference between wings level and 5 bank towards operative engine, I figure out there is also a difference in turns, right?

For example, if it fails and because of course you don't have an instant reaction, the airplane reaches a bank angle towards the dead engine, let's say 25 degrees, if VMC rises in this case it will reach a value maybe even above blue line, in this case the recovery is to reduce all the power on the operating engine and to hope you haven't already strike the ground. That's why i'm strugling to figure it out, I think there is a great difference if VMC changes with bank angle in a manner that you can't go back to wings level using opposite aileron. Maybe VMC is just for straight and level i.e. you still have aileron to control the roll and when you reach wings level you can maintain straight and level, but they seem to be coupled yaw/roll loss of control, don't know, just very confused about it.

Actually where I don't get it is if below Vmc you still have control to oppose the roll and to level the wings back or assume the 5 degrees bank into the operative and so reaching again the attitude where you can maintain straight flight. This is what confuses me at all.

To be more precise: you fly at VMC, banked 5 degress towards good engine, you can maintain straight and level flight using this banked 5 degrees attitude and also using full rudder. But let's say you bank 5 degrees towards dead engine because you want to turn in that direction, you don't have anymore rudder if hypotethical you want to assume straight flight using that banked attitude toward the dead engine, but you still have the possibility to roll back towards the good engine and there you have again the authority to maintain straight flight, right? Or I'm wrong and since you left the 5 degrees attitude towards good engine you lose all control and can recover only if you reduce the power on the good engine?

 

[thevideographer]

Nope. Prior to my MEI ride, I did commercial steep turns into both the dead engine and into the good engine and it flew just fine.

But what type of aircraft was that, a Seminole with no critical engine? It might be different in a turbocharged Baron with a tiny rudder and the critical engine failed. Of course, it should still be fine as long as you keep your airspeed up.

 

[A150K]

I think Bill Kershner is the only person to ever spin a seminole and live, took him something like 12000 feet to recover.

I seem to remember our very own Doug Taylor posting about having a student spin him in a light twin some time ago. I could be wrong though.

 

[A150K]

Never sacrifice control for performance. The common example is the engine crapping out 300 AGL, student sees the trees coming, starting pitching up to stretch it and spins it in short of the trees. I'd rather hit the trees in control, than auger it in and guarantee my demise.

A DPE I've heard of, does a Vmc roll with MEI applicants prior to their ride in the 'Nole. My good friend said the snap happens incredibly quickly, not that "oh no, the nose is 0.1˚ off to the left, time to reduce power." My good friend didn't take it all the way into a spin, since it's not approved for such maneuvers, but inverted in a 'Nole is not exactly a friendly place. "Control, roll" I believe is what the old-fella said to my good friend. Reduced the power on the good engine as soon as it rolled over, pitched the for the horizon (took a half second to figure out which way that was exactly), and rolled it back to the green side down. Recover as usual from that point...

My good friend said it was humbling to see what happens when you don't stay ahead of your students. Obviously, I would never take it that far with any of my students, but I think it's probably a valuable tool for MEI's to see before they start teaching others without ever having seen the danger themselves. I've heard horror stories of the twin Comanche, too.

Is that DPE suicidal, crazy or both?

 

[Hacker15e]

Never sacrifice airspeed for altitude. Altitude may be good life insurance, but nobody ever benefits from their own life insurance policy. Airspeed is life.

If you are flying low altitude at high speed, you want to do the opposite and exchange airspeed for altitude. "Climb to cope".

So....not so much for the term 'never'.

 

[rd757]

Is that DPE suicidal, crazy or both?

Neither, lots of experience and aerobatic experience. Well, maybe leaning towards the crazy side.

Remember, I didn't say they spun it, just took it past the normal 'Vmc Demo' recovery point. It's recoverable all the way until it hits the spin... which is well past the inverted point. Reduce the power, put the nose on the horizon (whichever way that is) and roll it out.

Or so I'm told anyway.

 

[rd757]

Same thing I knew, but if so, it's confusing, how does it come the explanation that VMC changes with bank angle? If there is a difference between wings level and 5 bank towards operative engine, I figure out there is also a difference in turns, right?

For example, if it fails and because of course you don't have an instant reaction, the airplane reaches a bank angle towards the dead engine, let's say 25 degrees, if VMC rises in this case it will reach a value maybe even above blue line, in this case the recovery is to reduce all the power on the operating engine and to hope you haven't already strike the ground. That's why i'm strugling to figure it out, I think there is a great difference if VMC changes with bank angle in a manner that you can't go back to wings level using opposite aileron. Maybe VMC is just for straight and level i.e. you still have aileron to control the roll and when you reach wings level you can maintain straight and level, but they seem to be coupled yaw/roll loss of control, don't know, just very confused about it.

Actually where I don't get it is if below Vmc you still have control to oppose the roll and to level the wings back or assume the 5 degrees bank into the operative and so reaching again the attitude where you can maintain straight flight. This is what confuses me at all.

To be more precise: you fly at VMC, banked 5 degress towards good engine, you can maintain straight and level flight using this banked 5 degrees attitude and also using full rudder. But let's say you bank 5 degrees towards dead engine because you want to turn in that direction, you don't have anymore rudder if hypotethical you want to assume straight flight using that banked attitude toward the dead engine, but you still have the possibility to roll back towards the good engine and there you have again the authority to maintain straight flight, right? Or I'm wrong and since you left the 5 degrees attitude towards good engine you lose all control and can recover only if you reduce the power on the good engine?

What is the 5 degrees of bank into the operating engine giving you? Effectively it's giving you more rudder. It's using the HCL to your benefit, so you can ease up on the rudder a little bit. In your hypothetical situation, you mention that you're flying at Vmc, by definition this is the speed at which the rudder has lost it's effectiveness. The airplane is going to yaw and eventually roll in the direction of the dead engine, because the asymmetrical thrust is overpowering the effectiveness of the rudder, even with the aid of the HCL (5 degrees of bank into the good engine) giving you that "extra" rudder. If you're below Vmc, that means you've already lost control effectiveness... It WILL yaw and roll, only option is to reduce power and control the nose... unless you're in the region of the graph where it stalls before reaching Vmc. The latter usually occurs at higher density altitudes where your Vmc is so low, the wing stops flying before your rudder stops working.

 

[A150K]

Neither, lots of experience and aerobatic experience. Well, maybe leaning towards the crazy side.

Remember, I didn't say they spun it, just took it past the normal 'Vmc Demo' recovery point. It's recoverable all the way until it hits the spin... which is well past the inverted point. Reduce the power, put the nose on the horizon (whichever way that is) and roll it out.

Or so I'm told anyway.

I'm still not sold on the idea of doing intentional VMC rolls. Great learning experience? Sure. Excessive risk? You bet your ass it is.

 

[rd757]

I'm still not sold on the idea of doing intentional VMC rolls. Great learning experience? Sure. Excessive risk? You bet your ass it is.

All about risk mitigation... just like everything else. I'm not saying go out and try it with a student. That's a death wish.

 

[///AMG]

If you are flying low altitude at high speed, you want to do the opposite and exchange airspeed for altitude. "Climb to cope".

So....not so much for the term 'never'.

As a corollary, people make a big deal of getting below corner airspeed at low altitude. Granted (as you know) that is so that you have the airspeed to maneuver, and presumably climb to cope, but maybe airspeed is still life?