Boeing 737 Unable to Trim!! Cockpit video (Full flight sim)

yeah we're still about three degrees away from full closed down trim and I am using everything that I have my god hi everybody better welcome to mentor and general video podcast as always I hope you're doing absolutely fantastic today on the video guys I'm gonna talk about the condition known as miss trim a condition that makes it very very hard to manually trim the stabilized from 7:37 I'll tell you what causes it and what can be done to solve it and at the end I will also answer a question that a lot of you guys asked me about last week's video about the terrain escapement stay tuned this video is brought to you in cooperation with our sponsor know what VPN now if you're like me and you travel all over the world using public Wi-Fi well then you definitely need the services of Noor VPN to keep your data secure and to make sure that you can always access those favorite series of yours even though you might be behind regional firewalls those of you who uses this link here below together with a coupon code pilot will get a 75% off on the three-year plan plus one month off so check it out as well so it will become almost impossible to move it so now we are at about three degrees here we're still about three degrees away from home walls down trim and I am using everything that I have thank you [Music] right guys so Miss trim now um in order to understand this you have to understand how the trim system of the 737 works now I've done a video about the trim system in a previously and a link to it up here but if you're interested in this if you're interested in getting kind of updates on you know things that's going on in the aviation world or explanations of how the 737 but basically anything in the aviation world works well then make sure that you've subscribed to this channel and that you've highlighted the notification valve because if you haven't you might not get these updates when I'm sending out new videos so the 737 trim system works like this you have a jack screw in the front of the stab lights that the stab lives there is the entire back wing of the aircraft in the front here there's a jack screw connected now that moves the whole stabilizer up and down through a pivot point okay what's moving the the jackscrew is in most cases an electrical motor so it's a single electrical motor that can be activated either by the pilots by using the thumb switch on the yoke or by the outer pilot who is doing the same thing essentially now we the pilots can only activate the trim if you fly manually if we actually activate the trim while the other policy engage that disengages the autopilot so in most conditions when you see that the stab trim is just a trim they're just next to the captain right and the first stops from the left when you see that moving its either being activated by the pilots war by a system called speed trim system okay and we're talking about the 737ng here so to speed team system or the pilots or if the other pilots engage the outer pilots doing and the reason that we have the stream system at all is because the we're operating in a lot of different speeds and depending on what speed are operating in the forces on the elevator and the aircraft would be different so let's say that I am I want to climb well in that case I will take my yoke and I'll pull it backwards that will deflect a an elevator surface on the back of the stabilizer like this will create downforce and since you have a downforce in the back that will move the nose of the aircraft up all right but of course if I only have the elevator that would mean that if I wanted to climb consistently I would have to sit with the same kind of back pressure to make sure that the aircraft keeps climbing and the amount of back pressure needed is going to change if I'm at say 220 knots off to take off go to 250 up to 300 knots so the client potentially this changes okay the same is when you guys move around when you've had you know your meal your coffee and your glass of wine and you won't go to the toilet you know there is a long queue at the front well let's do this long queue at the front means that a lot of people is in the front which means more back pressure needed so we need to be able to trim those forces away and we do that through the stab Liza alright so far this is very similar to the video that already did but in some cases the electrical motor might not be doing the job we wanted to do or there might be some other system interfering and in that case if the pilot feel that we're not happy with what the stabilizer is moving and doing we do something called run away stabilizer memory items and then run away stabilizer checklists okay I've also done a video about that you can check it out how it's done but but you have to understand and why this video is a little bit different is that depending on what speed you have when you get to the last part of the of the run away stabilizer checklist it tells the pilots to trim the aircraft manually okay so this is different from using the thumb switch this means that we actually have to turn the trim wheel manually because the 737 has something which is unique to modern aircraft and that is you actually have physical wires moving from the trim wheel down under the floor of the cockpit all the way through the back of the aircraft out through the through the the bulkhead half bulkhead to the jackscrew so close of jackscrew you have a drum which this wire is kind of rolled around and then it goes back up to the cockpit so as you're moving the stabilizer manually if you now fallouts the handles and you start trimming the aircraft manually what you're doing is you're using pure muscle force in order to move the stabilizer as you can imagine you're now moving you know several meters of wire and you only have a very little kind of pivot point to move around so you are potentially going to need quite a lot of force now during normal speeds when there's no much forces acting on the stabilizer it will be perfectly doable it's easy but and this is something to remember even if it is fairly in trim or fairly low speed it's still much more slower so as you're moving the stabilizer you are going to move it at a much slower pace and the electrical motor would okay good but now we're getting to the point here and which is what I'm going to show you here in the video in a second as well so if you're in a situation now where the aircraft has gotten severely Ogletree because of a runaway stabilizer for example and the speed has started to increase well then you have to understand that any flight control surface will become much more effective at higher speeds that's because the the aerodynamic pressure on the surface doesn't increase linearly like like this it increases exponentially and this is important to understand because that means that the force is needed in order to move a flight control surface at 220 knots is very very different from the forces needed at about three hundred three hundred and forty knots which is our V mo so if you have the stabilizer like this you have the jackscrew moving here in order to move the entire surface and at the back you have the elevator moving okay let's say that the pilot flying is now forcing a severe down tree movement this would mean that the pilot flying is is holding a lot of back pressure to all the aircraft at level flight the way that the elevator is now deflected is like this because remember it's trying to create of downforce here to move the nose of the aircraft up so it's deflected like this the jackscrew is here and remember if you want to trim out this what you want to do is you want to move the entire stabilizer like this so that the entire stabilizer is now angled in order to create a downforce but since you have the pivot point here the elevator is here the elevator is actually causing a force that moves the stabilizer the other direction okay and this is going to put a lot of pressure on the Yak screw so if you're sitting at high speed like this with the elevator deflected like that you are going to need an enormous amount of force in order to move the stabbed Lizer this way okay this is essentially what a miss stream situation looks like okay now I'm going to show you now in the simulator how this looks you have to understand a few things first of all this is a 737ng simulator I'm not trying to simulate anything else okay also I am going to artificially put the aircraft into I'm very out of trim position that is - in order to show you this particular phenomenon okay so this would be well well outside of what normal conditions would ever even know normal conditions would ever show but I wanted to show you the aerodynamic implications of a mystery at high speed so I will simulate another failure that causes the aircraft to get up into a higher normal speed and then we will Auto fishel II move this disturb less extreme into a very outer trim position just to show you the kind of forces needed okay so enjoy okay so I'm trying to establish this down check we are descending probably are you feeling trouble with the fur any trouble with the flight controls yeah it's I'm trying to print trim it but it's contained is to trimming against me when I'm dreaming so it's the malfunction please yeah this doesn't look right looks like do you how do you feel this stabilize the trim system can you control it I am trimming it and it is responding but it's a stabilizer if you agree for every time that I trim backwards just keep trimming for but okay forward yeah it's a runaway stabilizer okay so run away stabilizer memory items and I'm trying to keep this thing at 4 degrees coaching column hold firmly oh I am how to pilot if engage disengage is this engaged auto throttle if engage disengage it's if you can disengage it for make sure that it's disengage thank you engaged and do you feel did this the failure stop negative no it's still move actually in cut up switches to cut off okay it stopped it looks like it stopped okay you know I'm I'm using almost full back pressure exactly how many degrees I'm an integration those down or we have photo unit for units nose down now four units nose down yeah poster four units nose up purchased yeah okay so I am I'm struggling I'm actually using almost my full force to keep the aircraft level here you want me to help you what I would like to do is put it for the sake of exercise can you trim it forward and see if we can reach even zero nose down and see if I can even hold it so now we're doing this just as an exercise guys do not try this at home this is Lorenzo moving the aircraft we're at 300 knots now fighting I'm struggling to keep this aircraft flying my god yeah the thing is that with a higher speed the forces on the stabilizer will be higher and higher as well so it will become almost impossible to move it but so now we are at about three degrees yeah we're still about three degrees away from full nose down trim and I am using everything that I have my god and this is realistic guys this is this is how much of effort it would take to trim the stabilizer at these kind of speeds practice still control it though but it is getting harder and harder and remember we're still two and a half degrees away my god that's not possible is it alright so we will keep with stop there the reason that we have to try the reason that we have to trim this manually it's because this in the normal trim system would not do this okay it would require manual trim to get it away from this that's fine perfect trim it backwards trim it back with this new cap oh my gosh okay you're on press the red button press the red button now Wow right guys so as you could see it was very very hard for the first officer to move the establecer now it's still possible all right if you have a to pilot effort you will be able to move the stabilizer but it might be very very hard and it might be felt like if the stabilizer trim was actually stuck like it doesn't work now boeing was well aware of this all right and they have been aware about this since the first iterations of the 737 so back in the 1960s there was actually a description inside of the manual of this particular problem it said that if you do find yourself in a midstream position at a higher speed you have to do one out of two things right probably both one of the ways to get rid of this is to make sure that you don't have that force from the elevator acting on the jackscrew anymore and the way to do this is to increase the pressure on the elevator you make sure that the nose of the aircraft starts rising and then let it forward so let go of the elevator when you do that the forces on the jackscrew will reduce and you'll be able to momentarily trim the aircraft in this case backwards now that will go quite look like slowly so you might have to do that maneuver over and over again and that's why Boeing referred to it as a roller coaster maneuver so where you pull the aircraft up into a slight climb let it go the aircraft is now going to pitch forward you're probably gonna get into something close to zero G's and while you are at that position you'll be able to trim the aircraft backwards and then you'll have to pull it back again do the same thing again and eventually you'll get into an interim situation right so that's one thing the other thing is consider reducing speed okay because as you're reducing speed you might get closer to an in trim condition even without moving the stabilizer and also the forces acting the flight control surfaces is going to be lower right so consider reducing speed consider unloading the stab lights using this rollercoaster maneuver it's also an individual movement like that it's called a bunt you might have heard that you probably have done it as part of your flight training if you've done your ppl ru Cpl training but it is by unloading the forces on the elevator in order to get the tree moving again so it's in there it was described in the manuals of the 77 200 then it kind of moved out into a separate document which is called the flight crew training manual which is where it lies now all right it is still there the flight crew training will manual describes the fact that you will need more force at higher speed and larger outer trim conditions but it doesn't actually explain the roller coaster maneuver anymore okay but there are ways to get out of it right so if you have questions about that guys I really really want you to get into the master aviation app and asked me directly just hang out mentor inside of the chat there or you can talk to any of the other seven three seven pilots air boss pilots pilots in training or flight enthusiasts it's a great great community and if you want to join up you have the free download links down here so please go in there and check it out another question that I got a lot during and after last week's video was why during the terrain escape maneuver why didn't you just turn alright it's a great question let's have a look at the terrain escape maneuver in order for you to kind of recap on what happened this meant maybe I'm not very sure the moment this is the highway actually three three four palace set terrain 320 degrees 25 tracer decreasing rally altimeter increasing its grace okay so we can keep 20 degrees and that intermittent stick shaker if we need it if 20 degrees and radio t meter increasing that was iterate terrain terrain pull-up terrain to be using airspeed low pitch limit indicators we still have a caution I came to meet the Sikh faith after a jury original team of decreasing terrain terrain we're glad to read [Music] [Music] reducta meter increasing reducta meter increasing thank thank okay so here you can clearly see that I'm turning in towards terrain and instead of continuing to turn towards the runway or turning to what lower terrain I execute the terrain scape maneuver why is that well in order to understand this you have to understand the kind of position that you find yourself in if you ever get this kind of warning okay first of all you should never ever ever find yourself having to do a terrain escape maneuver and that's because before we do any kind of approach we thoroughly briefed it to make sure that both of us is aware of what's going to happen and we have something around the airport called an MSA which is a minimum sector altitude and whenever we're not on a approach procedure we would make sure that we're always over that or on the positive rate of control that MSA will give us at least a thousand feet separation to any obstacle within a 25 nautical mile area okay so that stops us from getting close to train when we're flying on route we fly according something called the Mora which is minimum enroute altitude and that Mora will give us thousand feet separated separation terrain in some case 2,000 feet separation terrain depending on how the terrain is so that means that anytime that you find yourself with a hard terrain warning something has gone terribly wrong all right you've lost your situation awareness something has happened you have either mistaken where you are you've done the wrong turn something has happened that has degraded your situational awareness to an extent to where you're now facing a terrain threat ahead of you at that point there is no room for trying to figure out what's happened you to closest rain okay you can't start figuring out where did you try left-right or anything no Boeing just wants you to execute the terrain escape maneuver and that is straight ahead because any turn will degrade your client performance now the only time that you might consider turning away from terrain is if you have if you've gotten the initial caution terrain warning and your visual okay so you can clearly see that there's a mountain straight ahead or an obstacle straight ahead and it's clear to the sides well in that case yes you can turn visually but if you find yourself IMC and you deaf and you get a terrain terrain pull up warning there's no choice anymore we don't want pilots to start to think that it's not a question where they are we just want them to immediately execute this terrain escape maneuver to give them the absolute highest chance of survival and that is why we do not turn okay the the manual to clearly state this we know that pilots on the severe duress severe stress will not make the best you know judgment decisions they just need to know that when I hear this we need to do this okay because it has been proven over and over again over the years that this is the safest way of doing it and I hope that answers your question okay guys that's it that's what I wanted to show you I hope that you have no more questions about that if you do once again into the app go into the chat tag at mentor and I will try to answer it for you right guys finally before I go I just want to send a huge thank you to the sponsor 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Channel: Mentour Pilot

Views: 354,863

Keywords: Mentour Pilot, Mentour, Boeing 737, Jack screw, Stabilizer, Stabilizer trim, Miss-trim, MCAS, Runaway stabilizer, Aviation facts, Aviation, Fear of flying, fear of flight, aviation phobia, takeoff, cockpit video, Flight control problem, Boeing 737MAX, Boeing 787, Boeing 747, Airbus 380, Airbus 350, Pilot struggling, max 8, plane crash, mentour pilot mcas, aeroplane inside video, mentour pilot 737 max, jackscrew plane, jackscrew boeing

Id: aoNOVlxJmow

Length: 24min 8sec (1448 seconds)

Published: Fri Apr 19 2019