Multi-Engine Training - Part 2 - VMC (Minimum Control Speed)

VMC or minimum control speed may very well be the single most important concept you need to understand when flying a twin-engine aircraft in this second part of the twin-engine training videos doc Rosenthal and I will explore what BMC is how it is demonstrated during multi-engine training how we recover once we find ourselves approaching VMC and how that fairly benign BMC demonstration we see during our training can quickly turn into an uncontrollable situation unless deliberate action to its recovery is taken therefore if you are flying twins today or plan to learn how to fly twins please watch this video understanding what we cover in the next 20 minutes may save your life and the lives of your passengers when on that unlucky day an engine on your aircraft fails for real [Music] skipping over all of the items that are essentially the same as the as the bonanza that really starts us with an engine failure during takeoff before VMC and that begs the question what is V MC v MC according to part 23 is decided is defined as the minimum control speed with the critical engine inoperative it's marked with a red radial line on most airspeed indicators the minimum speed at which directional control can be maned under a very specific set of circumstances outlined in 14 CFR part 23 air worthiness standards that's how the airplane was certified that's how they determine this the flight test pilot must be able to stop the turn that results when the critical engine is suddenly made and operative within 20 degrees original heading using a maximum rudder deflection and a maximum of 5 degrees of Bank and that would be into the dead end of a good engine and thereafter maintained straight and level straight flight with not more than a 5 degree Bank there is no requirement in this determination that the airplane be capable of climbing that's key we're going to talk a lot about that yeah at this airspeed VMC only addresses the directional control let's talk a little bit about what happens and the way the ACS describes that this should happen so first we need to talk about the critical engine both propellers on a baron turn the same direction so that means that the left engine the descending blade is close to the fuselage and the right engine the descending blade is far away from the fuselage right okay so you remember P factor okay so explain to me what P factor is well if I if I fly with an angle of attack where the the the prop if I think of it as a disc is not completely perpendicular to my direction of flight then the one blade down or up is different angle-of-attack to that then the other one that's exactly correct okay so the left engine descending blade is taken a bigger bite and so if the airplane if the crankshaft is parallel with the relative wind okay are these the ascending blade and the descending blade are going to what create the same amount of thrust now as we slow down and increase angle of attack what happens to the descending blade it has a higher angle of attack and produces more and what happens to the ascending blade lower angle of attack so it's pulling less and so what happens to the thrust of line of this propeller it moves to the to the inside to the right correct okay and that's actually kind of a good thing right because there's less you know it's it's moving closer to the center virtually yep conversely if we lose this engine and now the right engine is doing the work and this one's dragging what happens to the angle of attack of the descending blade over here it's increase also and these angle of attack of the ascending blade is decreased and what happens to the thrust line it's moving to the outside that's correct but we don't want it okay so what's gonna happen to this airplane if if if we're flying along and I reach over and I pull the mixture on the Left engine huh okay what's gonna happen to the airplane that's gonna yaw to the love okay it's going to yaw this direction right is it gonna turn that direction eventually but not immediately it's not going to turn right it's gonna pass through the air sideways right okay in our training we're gonna attach a yaw string you ever fly glider I didn't know and it had a yaw string right yeah really incredible piece of equipment just a piece of yarn and we're gonna tape a piece of yarn on the windscreen mm-hm so we can see which way the air is flowing so which way is the Austrian going to be gonna go when I pull the mixture on the left let's see y'all to the left so the y'all string will be to the left that's right so it's going to come this direction right okay so now the airplanes passing through the air in a side slip right mhm what's going to happen to our drag as a result of that it'll increase quite a bit correct okay how are we going to fix that right rudder that's right so now we put in some right rudder and the airplane moves this direction okay so when we put in that right rudder and the airplane is moving this direction it's going to take a lot of rudder and to counteract that we put some Bank in here we raise the dead engine the Austrian will be in the center the airplane won't turning and that will allow us to ease off on the rudder okay and so now we've got wings level this engine stops the airplane yaws we put in rudder to counteract it bring it back and raise the dead and the Austrian will fall in line and now the airplane will track at the in the lowest drag configuration straight through the air that's what we're trying to accomplish because in reality when we lose 50% of our horsepower we lose about 70 percent of our performance because of the additional drag of this engine and the cell and this rudder out here everything's going against us right okay so the VMC demo that we're going to do in training what will happen is we will simulate windmill and propeller we will simulate full power on the operating engine and we will start slowing down and pull in the nose up very slowly and as we slow down what's the airplane going to want to do y'all be quiet will it want to on first because there's only thrust on one side but then the more we slow down the more the P factor adds to that effect so the thrust line moves farther away from the center of the airplane if this engines inoperative if that one that's not a factor okay what other reason do we go to or we go plane gonna try to y'all what happens to the rudder as we slow down becomes less effective right okay so we're gonna need more rudder mm-hmm at some point this rudder is going to be at the stop and then the airplane will start to y'all we can't give it any more rudder we can't give it any more rudder we've got our five degrees a bank in okay and the airplane starts to y'all when that happens that means that the power from this engine pullings this direction has overcome the horizontal component of lift of the deflected rudder and the horizontal component of lift of the banked airplane uh-huh all right so when that happens we overcome that and the airplane is going to start to yaw and it'll be a very benign yaw okay and not really anything to get terribly concerned about we would it would it would seem and this is especially true your fault we're gonna fly aberrant but if you were flying an Aztec or a Seminole or a Seneca or a Dutchess all airplanes which have half as much power as our baron 180 horse instead of 300 okay and they have a bigger vertical stabilizer and a smaller rudder okay so they have very benign VMC characteristics but we're flying a baron and back in the 60s the army used t40 tuesdays multi-engine trailers trainers which is a b55 baron and they crashed several of them in VMC accidents and it caused a big investigation and all of you know and in I think some learning occurred from that but what let's go back to our yaw string if we deflect this rudder and the vertical stabilizer and we drew a line from the trailing edge of the deflected rudder to the leading edge of the vertical stabilizer what would we call that line cord line court line okay that's right remember though we've got this deflected rudder and a vertical stabilizer and the line that goes from the trailing edge to the leading edge that's the cord line of this wing because in reality it's a wing mounted vertically right generates most of the time the rudders in the center and it's just providing stability a stabilizing force but when we call upon it when we deflect a rudder it generates left one way or the other okay so there is lift there and to create lift we need what angle of attack right okay how would we determine the angle of attack of this vertical stabilizer the same as with any wing right it is the cord line to the relative wind how would we determine the relative wind in this twin-engine airplane we can look at the string to the Austrian all spring okay so if we draw a line from the trailing edge to the leading edge to infinity and we draw another line that's defined by the Austrian where those two lines intersect what do we find at the intersection of those two lines what would we call that angle the angle of attack that would be the angle of attack of the vertical stabilizer so if we have an airplane that's got a big long vertical stabilizer and a relatively small rudder is that going to have a greater or lesser angle of attack for a given amount of yaw a small rudder would have less and a big vertical stabilizer thank the Aztec great big tail on the Aztec and it has 250 horsepower and our baron has either you know 260 285 300 depending on what model were flying so big big difference in the angle of deflection or the angle of attack that's available to us so if we allow this airplane to start yawning the Austrian is going to move out this way right and we've got full rudder as the Austrian moves what's going to happen to that angle it's gonna get bigger and ultimately at some point in a high-performance airplane like a Baron or a twin Comanche between Comanche has a very small tail not a lot of power but a very small tail Aerostar all examples of airplanes that have fairly critical VMC's because in the Aztec or in the Seneca this all that happens is we overcome the horizontal component of lift and the airplane Yas but it doesn't have enough power to exceed this critical angle of attack and so the VMC demo is prescribed in the ACS is a very benign maneuver the VMC maneuver that will kill you in a barren or in an era star or and twin Comanche starts is a very benign maneuver and when you exceed that critical angle of attack the horizontal component of lift on the vertical stabilizer goes from a bunch to zero almost instantly when this stalls what's going to happen to the airplane it's gonna y'all much biased on violence right and that's gonna do this wing this wing over here is hiding behind this wind milling propeller so six seven feet of it are blanked out not getting very good air the airplane yaws violently we're very close to stall speed anyway what's going to happen to this wing it's gonna drop it's going to stall and this one's going to accelerate and it's going to create more lift and if you're an aerobatic pilot which I don't think you are that is textbook snap and so the airplanes going to stall and snap and at this point it's going to go in and a snap roll in aerobatic language is a horizontal spin but when the airplane goes over you're gonna be in a spin and you're gonna have two engines and if you're in a 310 Cessna you're gonna have two fuel tanks out here and once those airplanes find themselves in a spin they're not going to stop so the VMC demo that we're gonna do in the airplane in training is we're gonna teach you what the VMC recovery is but the follow-on you know it's it's a very benign a maneuver it's a very benign and it's designed to be that way because if it becomes violent the potential for non recovery is high all right but it has nothing in common with the VMC maneuver that will actually kill you if you get slow in a twin-engine airplane with high power okay so if we're in this situation and we lose directional high angle of attack slow speed and we start yawning what do you suppose the recovery would be well I could lower the nose that would help and I could reduce power on the good engine that was in two things we do simultaneously and instantly lower the nose pull the power back the airplane will start to accelerate and will accelerate to blue line which we'll talk about in a little bit bring the power back in and then five degrees of bank and resume normal flight okay but that you know this spin snap spin scenario is not what we're going to demonstrate in the airplane because there's no safe way to demonstrate it and it has the in the Baron since we're so dangerously close to VMC a real VMC in the in the airplane itself the way we simulate this is by blocking the amount of rudder that's available to you and the airplane will start yaahh early you'll reduce power lower the nose accelerate to blue line bring the power back so the training maneuver that we're gonna do in the airplane will lead you to believe that this is no big deal mm-hmm it's a very big deal and it's especially a big deal baron twin Comanche Aerostar high-performance small tail light twin yeah that makes sense that's what we're trying to accomplish okay I've got the aircraft across okay we talked about the BMC demo in the classroom right yes we talked about the fact that the BMC demo that we do in the 8 in accordance with the ACS is really redo of the BMC determination that was done in flight test when the airplane was originally certified okay that really doesn't have anything in common with the BMC that will occur inadvertently and a bad time in the flight and so we're not in doing this maneuver we're not in any way shape or form replicating what will happen if you experience a VMC the reason why we're doing this is to train the recovery method if you sense that okay okay look up and say oh my god I'm really slow and the airplane is losing any control we're training a recovery method but the reality is we just don't want to be anywhere near BMC in a real one engine inoperative because the risks are too high there is no time the only time it's okay to be below blue line in a real one engine inoperative scenario is when we have reduced power and the operating engine to land otherwise we fly blue line all the time and if the airplane won't climb we fly blue line until we find a place and descend until we find a place suitable to land and then we make an offer importantly okay okay so we're gonna demonstrate the BMC recovery procedure by executing a BMC certification determinate determination now we're not actually gonna do that because we're gonna block the rudder because that the weights and altitudes BMC is so close to stall speed it would be dangerous so what the book says is we've got one wet one we're gonna push the props up we're gonna have one engine at idle thrust with billing and wind milling and we're gonna have the other one at full power and we're gonna slowly decelerate until we're no longer able to be to retain directional control okay so to do this we're gonna set our heading bug very and we're gonna hold headache very precisely a so we're gonna get here slow down or up to 7,000 feet okay I'm gonna pull one is just two idols Dan I'm gonna start coming up with the other one and I'm holding hitting five degrees of Bank half the ball then I'm gonna come in with full power and when I can no longer hold heading when I can't hold that heading idiot Walker when the airplane starts to turn there's the turn I'm gonna reduce the power lower the nose accelerate to blue lines and Razoo powers and we're gonna fly a blue line in a blue line we have plenty of excess rudder available to allow the airplane to fly that's the maneuver we want to accomplish okay got it well I hope you will never need to make use of what you just heard about I trust the time you spend watching this video leaves you better prepare shoot an engine actually fail on your twin s doc said flying twins requires a commitment to recurrent training so please make it a habit to practice what you have learned here with an instructor recognizing the approach of EMC and the recovery from it for those of you with a strong interest in multi engine flying and for even more details on BMC and several other related topics you can see a full length recording of my ground school session with Doug here as always if you like this video please give it a thumbs up here on YouTube and subscribe to my channel by clicking here see you next time [Music] [Music] you [Music]

Channel: Martin Pauly

Views: 89,936

Keywords: flying, twin engine, multi engine, AMEL, airplane, aircraft, beechcraft, baron, beech baron, doug rozendaal, rozendaal, pilot, instructor, flight instructor, VMC, minimum control speed, engine out, training, spin, accident, recovery, recurrent training, crash, flight instruction, instruction, multi rating, twin rating, ground school, airplanes, airplane take off, airplanes flying, pilot training, multi engine training, multi engine checkride, multi engine aerodynamics, cockpit view, OEI

Id: VcEg39NmxY4

Length: 21min 14sec (1274 seconds)

Published: Fri Jan 11 2019