Jet Engines

Airline Pilot Technical Theory
Written By Adam Howey

Transcripts are approximate. Email us if you have any questions.

Transcript Start

00:00

Sam. Adam jet engines. Yeah, jet engines. Well this runs through your blood. You're from Derby, the home of Rolls-Royce. Yeah, that's right. That make really nice cars. We're all very proud. No! nothing to do with the cars, I'm not interested in the cars, my Granddad who I didn't meet spent his whole career there, designing and building jet engines.

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Axial Flow and Bypass Size

00:26

But yeah. And then so we used to go and look at their jet engines in there museum when we were kids. So when you see them with the cowling off. Yeah. And that's like, ingrained in my brain that image of a axial flow jet engine and because that always strikes me, when you see on an aeroplane, you think of it with all the cowling, but actually step back, the jet engine itself is, I wouldn't say small.

00:51

But comparatively well, the turbo fan that. Yeah, yeah. They now they're so I think the 777. Yeah whether this rolls Royce or General Electric or whatever that they're wide enough to fit the 737 fuselage in the diameter of the cowling but that's mostly the fan. Yes. Yeah. And then if you took the cowling off is what you're saying?

01:14

You'd see the narrow core. Yeah. That's a lot smaller. 

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Principle of Jet Power

Yeah. So a hundred years of the jet engine which pretty much is almost but going way way back before, then the principle of jet power. It was the first century literally in like the Romans came up with the, the concept they created a device which kind of directed steam power.

01:37

Yeah, that ball. Yeah. Three two nozzles in it and it's spun a little ball. Yeah. On a sphere. It kind of writes in like a nice way. It said this was just seen as a curiosity at the time. Like. Yeah, somebody looked at it went, oh, that's curious but didnt do anything about it. Would like Indiana Jones raiding some tomb, you know and then yeah, find one of these devices is like use to open some giant door or something.

02:03

Yeah, I mean what about those squids or something or octopus? They like jet out to move. Yeah. For it's for. Yeah. Yeah, it's always nature. Yeah. The principal has been around for a long time. Getting back to the jet engine Newton's. Third law. Yeah, every action. There's a equal and opposite reaction.

02:25

Yeah. So a jet uses that motion engine. You sometimes they're called heat engines and their chemical reactions. 

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History, Whittle and War

So 1903 with the right brothers. Yeah, but then by 1927 Frank Whittle was already trying to patent the, yeah, the engine I got a confusion to like who. Really designed the first, you think it was the Germans.

02:54

German guy sort of, he has a bit of claim to it but Frank is kind of got there. He's got it in the bag, really, but I did feel a bit, sorry for Hans, Hans von Ohain, who actually did do quite a lot of work. We didn't really know that whittle is doing some work.

03:08

Okay. In those and then like a lot of British things, we like just sold it because we were broke. So yeah. So the yanks took it. Yeah. Yeah. And I think like the rocket engineers that famously were invited to to relocate by the Americans and the Russians and who got the best rocket engineers?

03:28

I think there was a bit of that in Germany with the jet engineer, okay? And they ended up in France forming Snecma. Okay. Which basically is now CFM, okay? Yeah. Say there is some of that from from the war but little is maybe because we're British. That's what we hear about the most but yeah the Americans credit have us.

03:50

They always put Whittle at the front of their story as well. Is then they took his ideas, his ideas. Yeah. And this was all going on kind of during know, we're really like there is yeah, but even before. Yeah, yeah. Because the first test flight from Frank, Whittle on a jet engine was 1941.

04:05

So kind of just after the war started but obviously been designing it a lot before that. Yeah, so it just strikes me as interesting that this was all it was almost like a race during the war but they're never actually was a some jet engine aircraft during the war.

04:20

Yeah. So some of the stories are that the British were the ones holding it back. Right? And the Americans got wind of Sir Frank Whittle and saw the potential of it or some other stories are that they wanted to win this war and the jet engine was for the next war that was away, okay?

04:40

And the Americans more so so they so they were still fighting, they thought the wars would gone longer because as the European sort of situation was perhaps coming to an end. They were still improving the piston engines because they were fighting the war with Japan. Yeah, which is why I think perhaps they're an aircraft exceed far, exceeded like the Mustang is like a it's like a suped-up spitfire because it kept pushing and pushing.

05:04

That's the way my mind sees it. But yeah. So I don't know how the changing gets lost, but the thread of it is, although it was envisaged by Whittle and the technology was far, far, far behind what, they imagined and patented and designed. So when we talk about there, the technology involved today, it's easy to see that in the 20s.

05:28

They were, they didn't have a chance of achieving some of the things that they, that they said, but then the tent, the advances, in the jet engine, from that time to today. If you just track them across the, the decades in their own right, they far exceed like okay you think of the modern world now and the internet and electronics, stuff like that.

05:50

But we're talking about materials engineering and fluid dynamics and I mean, the engine has a real fast pace. Yes, like this machine, exponential kind of, yeah, right evolution hasn't it and reliability efficiency. All those things have just gone but yeah, you don't necessarily a second world war, you don't I think.

06:09

But they were flying the, I think the Germans claimed to have shot down like by 500 allied aircraft using their jet fighters, but it's a disputed a bit. But okay, they were the first to fly, but the Meteor flew as well.

06:30

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Centrifugal Engine Evolution

So they're all centrifugal jet engines which is like the first, so like the. So anyone who like me has got a brother who's bit, a boy, racer. Who's souped up his car. I mean, a lot of cars now have a turbo and a supercharger. Yeah, they are associated with, you know, high performance cars but now they they use them I think for efficiency as well.

06:51

Yeah. But essentially they were taking the piston engine to the limits and they were fit in supercharger to it. So the Merlin engine that I said was in the spitfire that sounds amazing. It's supercharged. So you've got to get more air into it and of course as you go higher you know, the air is thinner.

07:10

And so these are some of the limits of propeller aircraft. Anyway never mind the actual propeller. So supercharged means you actually use fuel and to draw in more so turbo users waste gas to to draw in more air and but a supercharger use actual fuel to draw in. And I think they just took the supercharger to the limits.

07:34

I'm not sure. This is Frank Whittle’s mind process but that's got so how it seems and then they just did away with the piston part of the engine and the supercharger is is is a like the first jet engines which is called a centrifugal change engine, which we don't really, I don't know where they used any more but not in commercial.

07:52

Aviation they use the axial long thin but they looked totally different but they were the first ones. So they would be what they're The Meteor, is the aircraft. Sorry. But the engine was like the W1 and the these are the first genes of the centrifugal compressors. 

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Jet Engine Technical Description

Oh yeah, I don't know how technical we want to go into the engine because you could spend all day about if you notice there in simplicity but appreciate people, listening will have already studied yet engines.

08:20

But yeah, I did look through the ATP owners about how much they learn about it. I mean, I I find that the physics if you like of it. Like I never find that easy. A lot of it is described through equations. Yeah. And but I find some of it interesting.

08:37

Like I think it's most efficient if the speed of the jet velocity is exactly the same as the speed of the aircraft. Okay. Right. When you put that in practise, it means a turbo jet is is efficient at about 800 mph. That's way too fast. Yeah. So the reason we use turbo fans.

08:56

Yeah. Is because when you do the basic energy equation, either what's the right time for it? It's you can either move a small amount of air really fast or a large amount of air really slow. Okay. And you get the same thrust, but one is way more efficient. Is that, right?

09:15

Yeah. That sounds pretty good. It's basically putting this massive fan on the front means that you move a large volume of air. A small amount compared to a turbo jet, which has no bypass. Yes. Okay, so, just to state, the obvious, that turbo jet is a really thin narrow.

09:31

Like, we were saying earlier, and the turbo fan has this giant fan on the front. So if you look at like early 737s, I think 1200, you and I used to sit at the end of the runway in leads at any, if you remember but Ryanair was still flying into leads at that time.

09:43

B737-200 or something, okay? And engines, really narrow. Yeah, you wouldn't you would stand out in my life if you saw it today. Yeah, yeah. They are actually turbo fan, but the bypasses is ratios really small, okay. So they're still not only that, they're not just here by jets and I think even military you're a fire and stuff is still turbo fan.

10:04

Yeah, but the bypass ratios much smaller. Now we bypass a huge amounts, not just efficiency, a lot of that is noise as well and those, do you still love that Ryanair 737 coming in because it made a loads of noise and there was like black coming out the back of here.

10:22

Yeah well yeah, so that's summarises. You see when you dive into the is it right with the physics? The engineering mechanics of the and the form is and stuff. I I find it interesting but that's how a lot of it's described, and it's not my strong point, but what I do like talking about, is there the components?

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Components

10:42

Yeah, let's do that. Very fact, because there may be people listening who haven't studied at ATPL. So, let's really simply go through the parts of a jet engine and how it how it works. Yeah, just in dead. Simple terms. So big fan on the front. Okay, what happens to the air next?

10:59

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Compressors

Where does it go next? So that's that's where you see the cabin crew posing for pictures sound there on the cowl in which is the nice smooth rounded thing that shrouds the front of the fan. Yeah. The bypass ratio means the amount of air that passes around the side.

11:16

Yeah this is the amount that goes through the core. Oh yeah. So the fan is actually like a propeller on a propeller aircraft. Yep. And it's driven by a spool that runs through the centre of the core. Yeah, to the very back. So So it's a power that fan.

11:39

You have to first get air going through the back of the engine firing and then the low pressure turbine at the right back drives the very front of the engine. Yeah. Okay. And that's moving the air that we talked about and that's providing thrust. Yeah. But some air then goes into the core and starts to get compressed.

12:02

Yeah, by compressors compressor. Yeah. Okay. So compressed like, more than we can imagine like the compression of yeah. Like to a serious level of. I think it's insane. I think Trent 500. It's a trend is a Rolls-Royce variant river Trent. Yeah. I one of my local rivers. Yeah. That means a three spool.

12:25

All the trents are three spools. Okay. But you and I fly there A320 series which are two spools. Yeah so you've got N1 and N2 readouts yeah see and then one is your low I want to say pressure low speed spool. Yeah. And N2 is there high pressure spool, But the Trent 500, which I think you would see on A330 something like that is.

12:46

Obviously now we're on Trent 1000 that draws in basically 200 metres in front of that engine, right? And is sucked in every second and ejected every second. Okay, so that's a, that's a kind of nice way to so don't stand in the front of it when it's no because you can.

13:01

Yeah, exactly. So the compression to achieve that, that's insane. And if you went back to Whittle, he would get not, not a lot. I mean, the principle is like it sucks in so much air. If you just if you take a jet engine, that's the same physical size as a piston engine, right?

13:20

The jet engine just by just for its size, and it's weight sucks in way more air. Yeah, than the size of piston aircraft about 20 times more. Yep, and that's because these compressor blades are spinning around and they're like little aerofoils. Yeah, which might talk about in a bit because it, we might have to deal actually with that as pilots.

13:41

I mean all this stuff. We're talking about now. It doesn't really know any of it needs to know what happens if you move the thrust lever,you go faster. Yeah, and so, little little aerofoils been around incredible speeds and behind stationary ones, and then another row.

13:59

So you'll have lots of rows of these things. And then, the reason you might have more than one spool by the way, is because as there as you compress the air, the actual duct that the air is going through gets narrow and narrower to the blades can be shorter.

14:14

Yeah. So it's actually more efficient if they spin a different speeds. Yes. And that's why you have different spools and a different stages. Yeah. Yeah. So they compressor my favourite bit for some reason. Okay, nice. Yeah. So then this super compressed air then goes into the next phase which is the combustion chamber.

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Combustion Chamber

14:32

So, it's When I've read, I always visualised it with just something mixed with a fuel. I didn't realise. It was kind of like a spray. A few, like a fine spray, isn't it? It's like very, it's like atomized. Yeah, exactly. It's like in when you spray your aftershave on.

14:48

Yeah, you see that atomizer? I think yeah, yeah. I'm sure it's more complicated than that. Oh yeah. I think technologically, that is the hardest part. That's so overcome because the temperature that you actually get to is too hot, I think to burn the fuel. Yeah, because as you compress the air, the temperature rises.

15:08

Yeah. The speed that the air is moving is too fast. Yeah. So you've got to have these combustion experts to like we've got to burn fuel in an environment that doesn't want to burn. Yeah, yeah. And say you've got to have these complex ignition systems that a continuous. And then, as you burn the fuel, I think it lights, other fuel and, but then, as they obviously all this expands, that's great, you've got this explosion and that's going to drive the turbine, the next part, but you want that flow to be not to turbulent and so on.

15:42

And so, it's crazy. I think it goes in it. 150 metres per second. I think, is the airflow into the turbine, so imagine how fast the airflow. Imagine trying to light a match in a hurricane. Yeah, exactly. Yeah, yes. So though, the jet engine you can explain it really simply in these simple parts.

15:59

There's actually so much engineering gone on around it to make it all work correctly. And you know, like you say like the ignition has to compensate for the speed of the air coming in. It's, it's fascinating really. So, yeah. So, so we've got the in simplest form, the three, three things and need for fire, really, which is fuel air and a source of ignition.

16:20

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Turbine

So, and that happens in the combustion chamber. So then where does it go to that? Will have the turbine. Yeah. So that that drives turbine. Yeah so it's really hot. Yes. So work this out the the temperature in the turbines like 1600 degrees Celsius you might be relevant later actually.

16:39

Yeah. And talk about some accidents but the materials used in the turbine melt at 1200 C. Yeah. Okay, so it didn't ask me! but, you know, a long time ago, early jet engines, I think 60s that time my granddad would be working there. They're using titanium for these components say that, that is a long time ago to be using these advanced materials.

17:00

Yeah, that's the only way they could. You know, that's that when you think of back in the 30s and the 40s, there was no way of them having this technology that time, but pretty soon they were onto these advanced materials and now they're way more advanced and I don't understand they grow these blades from single crystals and yeah, also things.

17:18

But these turbine blades, which I have one and have tiny little holes in and for coolinf and I don't know, other reasons, but they're spinning very fast, 500 metres per second. And each each blade has 18, tons of force on it. So fugal force, something like that. I'll try to find the statistic.

17:40

Like how many London buses you can? Hang off a compressor, blade or press play for a turbine blade. Yeah, by fine. It's like an insane amount. How many episodes so strong? It would be, it would be crazy. So compress is spinning round. Ignite the fuel, then you go into the turbine.

17:55

And then you've got again, like the compressor, you've got rows of turning turbine blades, and then stationary ones, little aerofoils, directing the flow, and we're doing whatever that you want to the flow at that point to make it smoother or faster, or yeah. So importantly, then you're a starting to extract the energy and drive the compressor, and drive the fan in a turbo fan.

18:19

Yeah. Or I suppose we're not really talking too much about turbo props and turbo shafts. It's basically helicopters but all of the energy in those systems is then it to the shaft or that prop. Yeah, as opposed to a change in where you actually using the exhaust velocity to have the nerds use third law and of reaction.

18:38

Yeah. So then you've just got a lot of not hot noise coming out the back and basically, which is great. Yeah, I feel like when I was like a young boy, that's so exciting. But now we want them as quiet as they exactly. Exactly. And yeah good. That's it.

18:53

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Summary of Airflow and Engineering

Really. That is how a jet engine works. It's suck squeeze bang blow. Okay. Yeah yeah like that. You learn that way. Piston engine say. So suck you've draw the area in. Yeah. Compress it explode with the fuel and then it blows the piston up. Suck squeeze bang blow is the cycle of a piston engine in a jet engine we call it the Brayton cycle, but it's exactly the same.

19:14

Yeah, so squeeze bang black. Yeah, I like it easy way to remember it but what was it interesting to me? Is yeah, the amount of engineering that's gone into it to because yeah, it's not it's not no part is ideal. So everything has to on been safe, for everything else that makes sense.

19:31

And yeah, has to come in at that speed. So how can we provide an ignition? So you know the same thing just has to survive, you mean yeah. And don't forget, we've got these engines running for what like 16? 20 hours a day. Yeah. They just want to be running all day.

19:48

Yeah. And eventually they get taken off the wing and they get renewed and but they're just running the whole time that these temperatures for the turbine. If you looked in. I think my, my understand is right? It's glowing red hot, those those turbine blades are yeah, they look like they're melting.

20:02

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Pilots Point of View

Yeah, yeah. And what we want is just like this perfect airflow through it, but obviously work as pilots we're like doing all sorts to to the with taking the aircraft into all sorts of places and in the environment and stuff. Say the engine has to put with a lot.

20:19

Yeah, but it's running that whole time. I mean, my friend who's more of an outdoorsman like when there was the Hudson Sully, Sulenberger when they're double bird strike. So I think he said, why don't you just put chicken wire on the front of the engines just like perfectly legit question, isn't it?

20:38

Yeah you need engaged down the engine. Yeah, you're into frame with this beautiful perfectly built finally balanced. Yeah. Mechanical miracle. So you don't want to throw a bird down it ideally no. So why don't you just put chicken wire in front? Well it's all about having this uniform airflow airflow.

20:56

Yeah, exactly. Setting the chicken wire would disrupt that. Okay. So maybe let's talk more about the commercial. Yeah, side of engines and stuff so they're reliability. What else we used them for what it looks like and it's sort of day-to-day so they're obviously very reliable. I don't think you've ever had an engine failure.

21:18

Neither of I I think you'd be, they don't start sometimes but sometimes they want the ground. But yeah, I don't, I think you'd be you'd be unlikely to have one in your career probably an engine failure. You might have one. Yes, seems to be probably, I don't know, 50% of people, maybe have one in there.

21:33

Okay, an engine failure. So very, very reliable, considering the amount that we fly. Yeah. The amount of engines that you, you know, you might find a four engine aircraft eventually. So yeah, a lot of engine and a lot of time flying them. Yeah. To not really have an engine failure, he talks about starting proceeds, sometimes they don't start.

21:52

They're obviously been automated a lot nowadays, so it's just, I guess the analogy similar to starting an old car used to have like a choke and then you had to. Yeah. And then but then that evolved into like an ignition and like, yes and accelerator. Now it's just like a push button on most cars like you just press the start, is yours push to start?

22:13

Yeah, mine isn't okay. So yeah, okay. But it's, whereas an aircraft engine is similar. Yeah, has to have to, you know, manually start the engine and the some aircraft, you still have to do that. Whereas, well, there used to be an engineer. Yeah, engineer. Yeah. Who I guess a lot of his attention would be taking up by there, engine instruments.

22:33

Yeah, which I think basically, there is one for each suck squeeze bang blow. Those dials all day and get everything kind of. Yes I want to talk about starting I mean well no it was just I was just a little sidetracked really. I mean, it's just, it is a, how do you start an engine light in a car?

22:50

You do it electrically. Yeah, you just can't get enough. Electrical power to start this air size of jet engines. I think some you can, so we have to use another engine, which is called the APU. Yeah. And that provides high pressure air. Yeah. Which will spin in the, the engine around basically.

23:05

And once it's spinning, a certain speed, you throw a bit of fuel in and hopefully it all lights up. Yeah. I think like like layman people like my family and friends sort of imagine that I've got like a set of keys like yeah on like a like you would a car.

23:19

Okay. So talk to that. What else do you use? Sort of the, the power from the engine for like, what else does it power in the aircraft. So it's an electrical generator. Yeah, set powers and all the electrical system. Yep. And it pressurizes hydraulic. Yep systems. Yep. And it provides high pressure air.

23:40

Yeah. For all sorts of uses pneumatic, new users, and air conditioning. Say, pressure the aircraft and keeping the air conditioned. And yes, a lot of accessories and engine eyes. Bleed air coming. Yes it. So, the point I'm getting out is, if, if you have an engine failure, haha, you normally get a lot of secondary problems.

24:03

Like some right, some hydraulics might not be powered you lose yet. One of your generators. So that's one of the things we don't see often in our career. But we do see a lot in the simulator. Yes, six months, we tend to get engine failures and a lot of associated systems.

24:19

Obviously, a twin engine aircraft. You've got two or four engines and so and we've got the APU which had just talked about exactly power unit which is like a mini jet engine really. Yeah. So that can provide some bleed air. Yep. And for accessories and electrical power yeah which is maybe how we power the electrics on the ground.

24:37

Yeah. All we can do and provide air conditioning on the ground. Yeah. And we don't want to run jet engines on the ground because the very hazardous yes, as in when we're understand and we're near people and things like that. But you can refuel and technically load bags and stuff with an engine running.

24:56

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Jet Engines as Hazards

Yeah. Yeah. But you wouldn't want to go anywhere near it. Well, my favourite videos from we're at university was I know you guys a guy on an aircraft carrier. Yeah, he got sucked into might be a harrier. Oh yeah. I think it was a harrier and he survived because his helmet.

25:09

Yeah, yeah. It's because it's so grainy. It's almost comical. But yeah, sadly. A lot of people have died and from being sucked into engines and that would be not just being sucked in and the exhaust velocity is really high. So you see people stood at the end of runways hanging on to fences.

25:27

Yeah maybe in some less well regulated airports where the threshold is really close to yeah people. But if a bit of the wrong bit of debris happened to be kicked up, that wouldn't, they wouldn't enjoy it quite so much. I didn't top gear had like a Virgin, 747, blown a car.

25:45

It flipped a car over there. Yeah. A car drove in the engineer sort of, yeah, whether it's max power or not. But yeah, literally flips the car over. It was that powerful and the bleed air which I don't think would ever really be hazardous but when they're testing engines, you know, the bleed air is kind of just not being used for anything.

26:02

I mean that's so powerful that would, you know, decapitate you, if you like, go anywhere near it definitely. So definitely hazardous and on the ground, obviously, when we're, when we're around them need to be careful about whether we're running them or not. They provide a lot of accessories, right?

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Systems

26:19

Well, and, and run a lot of systems. I'm sorry, they're very and when we have engine failures, we have to deal with the loss of those or yeah. Having only one system provide, I mean, typically one engine drives one hydraulic system, the other drives the other, but it's back up and there's a way transfer options.

26:37

Yeah. Yeah. And not redundancy, but the pilot. I mean, so what you're talking about earlier with how automated they are, typically you'd call it FADEC, full authority, digital engine control. Yeah. So yeah, you don't need a flight engineer because the pilot has a lever, I mean, in the airbus, it's just a toy.

26:58

It's not actually physically connected to the fuel valve or anything. You know, if we if we just go full power, all of a sudden we're not going to put too much fuel into the engine like you would on a and a simpler single engine piston aircraft.

27:15

We have to gently put the power up or anything like that. The FADEC takes care of everything. Yeah the FADEC detects problems to the engine. Yeah. And that's been around a long time. Feel like systems. Yeah. But now there's people in Derby, in Rolls Royce, in control, rooms monitoring all sorts of parameters.

27:34

I have no idea in the engine for the health and the engine and yeah, and and the life of the engine. Yeah, So there's a lot of instrumentation in the engine but as pilots, you know, we just we just need the engine to do so. Yeah. I think our probably our knowledge of engines is it's getting less and less because to us like you say it's just a lever that we move forward and backward and yeah, I don't know.

27:57

I find maybe some new partner newer pilots have less. Yeah, understanding of a FADEC or flight engineer used to do or, you know, because it's is simply just an engine. That you, I mean, sometimes practical stuff we know about would be like, how slowly are to spool up? Yeah.

28:15

Because we fly high, drag approaches one of the reasons being that the engines are about 50% already. So yeah, it's a shorter time to go to take off. Go around power if we need it. Yeah, but being aware of how long they take to spool up because it takes a while to build up that air flow through the engine.

28:32

Yeah, the position of the engine. So, typically, under slung engines on aircraft. We fly means that there's a pitch power couple but not in the airbus because it's fly by wire. So these are some of the more handling practical characteristics, that pilots are aware of literally using the thrust levers, the the failures so we could talk about actual engine failures.

28:54

Yeah. And I think has reverse thrust is sort of interesting as well. But that could be its own whole podcast. I think probably could do a whole podcast on with so exciting here yeah or deceleration or something like that. Yeah yeah yeah incorporate. So yeah we've you and I haven't had an engine failure but you'll be giving them out all the time in the sim.

29:15

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Engine Failure

Yeah. The one I'm the only thing is we practise engine fairly on takeoff, quite a lot. And I saw a generation of pilots favourite videos there, 757 at Manchester Thomson. Where has it? Like two herons going? Yeah. Right at rotation. That's like the classic engine failure at takeoff.

29:35

Yeah, profile that that we have to fly because it's a high risk and a statistically a lot of people fail it. So we have to keep practising it, but the one I'm scared of if you like, is the engine stall or surge? Yeah, because I think that would be one of the biggest startle factors of your career.

29:56

Yeah. So I used to do a bit of teaching on it and my understanding is that it's so loud and violent. Yeah, it might not be too much of a problem, but it's so loud and violent. But perhaps talking about that, just, I don't want to gave it to technical stuff too much more, but it basically would help you understand that the flow through the engine.

30:16

All nice and uniform and in one direction believe it or not. There's little era for y'all and compressor blades can stall like a wing stalls. Yeah. And you really shouldn't happen in modern jet engines. But if there's something wrong with the engine, maybe like a bird's gone down it or something like that the you can affect the uniform flow of the air and if the airflow stalls I it's not travelling the direction or the angle that you want it to you can then get a surge where the thrust the engine's actually coming out the front.

30:50

Yeah, but just in one little explosion. Yeah. So they can be really loud bangs. Lots of vibration. Yeah, that could be and I don't think we train that scenario, very much no. And I've think it would be terrifying. I've started doing a few in the simulator and it's actually really loud, right?

31:05

Okay. The effects of the simulator are quite quite good and quite loud. And it's, yeah, it's it's a good one to do because it's not what we expect. Yeah, we train very much because we know what I'm in the trees, or maybe in the climb or something. What we do, we have an engine failure, but you've got that initial startle to deal with.

31:22

Yeah. And there is on the airbus the engine install checklist which me the FADEC might detect or you might have to call for the QRH. Yeah. And and that just basically says reduce the power and yeah. Maybe live with it or maybe not and then that's an interesting situation.

31:38

Yeah. So, a lot of the these sometimes you see on online are people from the passenger windows you film in stores and where you get fireball, come out the front or the back of it. Yeah, but yeah, really loud, bang. So we were saying you'd be very unlucky to have an engine failure in your career.

31:58

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British Airways 09

What about if you could really looking you had four engine failures in in one day, I wonder what you're talking about. I think, you know, I'm talking about. So as we always do maybe looking at little case study yeah, little accident and there's obviously a lot of accidents out there attributed to engine failures.

32:17

And yeah, but be a British Airways 09 and also known as the Jakarta right incident, it wasn't accident where they had all four engines fail. I think that's probably a good one to I think, say, because like you say, I mean every other aviation accent has some kind of here.

32:41

Yeah. Like that. Yeah. And but it's about demonstrates about tying in, with learning about the engine, the engine and how it works. Exactly exactly. So, so very briefly then, so the background. So this was Boeing 747 flying to, I can't remember it was going to actually, but was again, all sorts because it was doing it from London to that multiple legs, wasn't it?

33:03

But eventually to Auckland, was it? Yeah, that's right. Yeah, I think this one was to Melbourne. Okay. And then it would go to Auckland and it is took off from Singapore. Is it on this leg? Yes, that's right. That's right. So flight crew, just flying along in the cruise night time there, sort of about a hundred miles southeast of Jakarta in Indonesia and they get an St Elmos fire.

33:25

I think is the first indication they get some St Elmos fire on the on the windshield. Those you that haven't heard of St Elmos fire. It's like little what looks like kind of static. Yes, that's all. She put your hands on. Yeah. And then your hair sticks, her hair sticks out.

33:39

Yeah. A little this that's St. Elmo. And then they started to get some smells in the cabin, a sulfury smoking a bit, sulphur smell. And then essentially, as they were, just trying to sort of figure out what was going on. The number four engine, I think failed, first, followed shortly after by the other three as they lost all four four engines.

34:56

So what was happening? What was going on? There's three of them because 747-200 flight engineer. Yeah. And Eric 40 minutes into the flight Eric moody, the captain is already gone back. Yeah. And decided to go downstairs to the toilet. He claims someone in the upstairs to it.

35:12

I think I thought the 747 maybe now the engineers not there and there's more room, but I thought it had a toilet in the flight deck, but maybe that the 400 anyway. So he's downstairs. And I think they call him back up initially, because it's the most amazing St Elmos fire ever seen.

35:27

On his is way back. He starts to see smoke coming through the floor ducts, okay, but people can still smoke in 1982. Yeah. June forth and but this doesn't look right. These scientists smell sulphur. By the time it gets in the flight deck, there's more smoke. Yeah, but it doesn't when he recalls it, he doesn't seem that panicked that recalling at that time that there might have had a fire.

35:52

He's like, well we had fire bottles in the cargo containers and we could have turned around Jakarta in 20 minutes and all this. So he sits in his seat and like you say, then an engine fails. Yeah, but the RB 211, which my granddad had something to do with, which it would have had four of, I think, right about this.

36:13

There was a different engine originally on the 747. Okay, not Rolls-Royce. Okay. And they failed like every other day, really? I think every, so these just consistently fail at top of descent anyway. Not not all four. No, one. So maybe the new and I there might be slightly less of a statle factor.

36:32

Like number fours failed. And like you said and it's St Elmos fire. So they're looking for the thunderstorm. Yeah. But there isn't one and then they are running the checklist. For number four shutting down with fire bottles potentially armed I think and then they are the rest of the engines fail.

36:50

Yeah. But the problem with Eric Moody is he is so chilled. Yeah. Can't get a sense of how they felt at that point. So unlike Chesney Sullenberger at 2,000 feet. Yeah. There at 37,000 feet. Yeah, so I think on the airbus you glide for about three miles per thousand feet.

37:11

Yep. And but then you are in the sea at that point? Yeah. I said they was starting to think they might ditch. Yeah, they had some, there's a mountains to make it over on the coast of Indonesia to get to Jakarta and it was a gamble to whether they would make it overtons and their decision was.

37:26

If they weren't gonna make it over the mountains, they would turn back to see and try and ditch in the sea. But yeah, I read something about you say about Eric Moody being really chilled out. His PA is like it got a title of like the most understated quote ever.

37:42

I mean, I haven't written down. Actually even remember it. It was something along the lines of ladies and gentlemen. All four engines have failed. We're working on it. I hope you comfortable listening. Hey there's our dinner. Damnedest. That's right. Okay I'm going again. I trust you're not in too much to stress.

38:01

Yeah and which apparently had quite a common effect. Yeah these are British Airways pilots and say well she spent there's a quite a few statements I think that were like very understated that they may that the crew made to each other throughout. And when Eric Moody talks about it it's all like tea and medals sort of just in a day's work.

38:22

Like yeah. Yeah. And I think one thing that em may be saved them. So if that's right, they had to put on their oxygen masks so we would do that for any smoke fire fumes. Yep. Because before you're overcome by maybe the fumes or the smoke you need to protect yourself.

38:42

Yeah. So they put on their oxygen masks and the first officers oxygen mass. The pipe. The pipe disconnected. You imagine Eric Moody and the engineer have a little discussion or all three of them decided to descend so that they can get oxygen. Yes you know they get them they're descending anyway because all four engine felt but they sped up there decent.

39:04

Yes. And they increase their rate of descent. Yeah. Directly breathable. Oxygen. Yes. So I tried a sort of find a bit more about that decision making process, but I think Eric had a little discussion about it because clearly all your energy is is in your altitude. So if you suddenly descend down to 10,000 feet.

39:21

Yeah, it's not got that long now until you ditch, but it's about dealing with the biggest threat at the time. And so the smoke in the flight deck and in the rest of the cabin was sort of like the biggest threat. So they decided to send down to 12,000.

39:37

So they could clear the smoke out the aircraft. Yeah. Because I'm guessing there what they would do is open like a Ram air system. Yeah, so I purge the, the smoke. Yeah, three, which is similar to what we do in any smoke situation, which is maybe prioritise the descent, but they still got no engines.

39:54

Yeah, however, once they are at a lower altitude. Yeah, I think their flying engine was busy trying to start these engines the whole time. One of them started up. Yeah. So they obviously had descended out of the hazard. Yeah. So maybe we should rewind. Well, yeah. What happens now is that when we didn't know?

40:13

Well, yeah. So now we can turn it relative to the jet engine and why the jet engine failed, right? So those of you that haven't sort of read about BA flight 9, it was actually a cash that they were in. They didn't know but their Mount Galunggung in. Indonesia had erupted, obviously couldn't see the volcanic ash at night time but that's why they were getting the St Elmos fire on the windscreen like ash particles basically hit.

40:41

Not the windscreen and becoming electricity, charged. I ionized particle. Yeah. And obviously volcanic ash going into the jet engine. So what happens to cause the so it's a unfortunate trick of nature that. Yeah you get these fine ash particles less than two millimetres come out of a volcano.

41:04

Don't show up on weather radar because they're too small no moisture either. Yeah. And they happily go down your jet engine, whether the temperature, if you remember, is, I don't know, 1400 or 1300 degrees. Yeah, which is exactly the right temperature to melt the silica, which is glass basically.

41:25

Yeah. So now you've got molting glass, which starts to melt and build up on the inside of the turbine where that temperature is and effect. Effectively choke the engine. Yeah. Until you get a stall surge which we described because you've got a breakdown of the flow through the engine.

41:45

You're basically choking it and just the ash can actually choke up. I think the compressor as well. Yeah, so that's what happened to the engine and also the bleed air system is taken in this, this ash cloud and we all know that volcanoes smell like sulphur I think hopefully.

42:03

And so they were smelling that in the flight deck with this with this smoke that they thought they had which is actually the ash particles. So, all the engines gave up. Yeah, and one more thing as well, I want to put out a mayday. So you're gonna aviate. So you're gonna keep the aircraft from stalling.

42:20

You'll start this later. then navigate. Yeah, we're gonna ditch, we can give the mountains, communicate power mayday. Well, if you're in a big ball of ionized particles, yeah, statically charged your radios. Probably don't work very well. No, but I think was a problem. They had then telling air traffic control but luckily somebody kindly relayed.

42:41

Yeah, their transmission. Yes. Or it was a breakdown in the fact that they couldn't believe that they were saying, well four. Yeah, I felt they thought there's a numbers. Yeah, there was a bit of that as well. I think a bit of communication language barrier as well, potentially, what possibly happened was they dropped out the bottom of this ash cloud.

42:59

Yep. And you've got loads of air going through the engine. Yeah, it's starting to cool down. The glass is starting to break off and fall out in the engines become clear. And then they just start back up. Let's start by locally. Yeah, and they all forced our back up.

43:11

And for one more number three, I think didn't like it, so they shut it down, they didn't touch it again. Yeah, so they got three engines now but at one point they thought if we just get one engine going. Yeah. Which again, if they thought they could, or they would just theorizing the 747

43:26

can fly on one engine only but just limp around the island. Yeah, not over the terrain about 12,000 feet. So quite high. Yeah, yeah. So that's what happened is that, right? Yeah, yeah. That's perfect. It's below. And also, some of these ashes abrasive. Some is less abrasive but either way it does damage the aircraft.

43:47

So you're so their windscreen had been attacked by their sun blasted effectively. Yeah. Which will come on to, in a second, I suppose. Yeah, I guess it's less relevant, isn't realised? Yeah. Engine. But they hadn't realised. And as they came down, they diverted into Jakarta onto it. It was a localised DME approach which was a bit unfortunate that they didn't have a.

44:07

Yeah, kind of nice. Simple IS, but yeah. And so the probably there's a clear night and they said oh what's the vis? And they said, like, you know, unlimited and they said no no, we can't see anything. Actually, it's is the windows. I hadn't turned the lights on either.

44:22

Maybe said, they'd and bothered to put the runway lights on, but anyway, he flew a lot. The eyeless stood up, I think. Yeah, yeah. I mean, imagine they're flying like, you know, an approach to the engine failure on a 200. It's a lot of rudder input and yeah, balance of the and that, but they weren't stressed out by any of that.

44:39

And then he so repeats that about 100 feet. He could do this little slit to the window that happened, not to be affected, he saw that, they were about the right place, so he just sat down and went, oh, we're not gonna die now. And then he just, they did like a really smooth touchdown.

44:55

It's not really. Yeah. And then they were left baffled for a while. Yeah, it took him a long time to figure out it was no time or volcanic and they call volcano he call it sometimes. Yeah, I think so. Is you and I had a, I've lived through. Yeah.

45:12

What do you call it? The 2012. It was no 2010 when he 10. Yeah, but not pronounced that volcanoes named Iceland. Yeah, that stopped air travel around from. Well, it was kind of transit from like Greenland across most of Europe. Yeah, basically but we used to read an ashtam every day basically.

45:36

Yeah. It was called that and yeah say that. Yeah, a 1982 and then plenty of aircraft are flown into ash clouds after that. Yeah. But at that point, I don't think the aviation industry knew that much. Well even some flew into that same ash clouds a couple days after oh yeah like that Singapore Singapore flight and had an engine failure.

45:59

Triple engine failure same sort of thing. So and only then did they close the estimate? Yeah, exactly. And yeah. So but yeah, it kind of the point of that, talk about that accident, is it? Incident is it emphasises the habitat? Engine works and how any little disruption to that airflow.

46:22

Yeah. You know, don't can cause it's fail. We have also checklist procedures for it now. Yeah. Volcanic ash. Yes. What would we do? I'm, I don't remember exactly, but the first line is basically 180 degrees. Yeah, I think I remember. Just get back out of it. Basically, remember what I was saying about, it's just unfortunate, the silicon melts at the temperature of maybe like a cruise power setting.

46:46

Yeah. And doesn't an idle power sensor. If you just go idle the turbine and temperatures drop low enough that you won't start melting the glass onto the inside. So maybe a 180 and a dissent idle descent and then put it on usually put on the bleed engine anti-systems because they provider a higher margin for the on surge.

47:10

Yeah, and situations and that's pretty much it. However, I say something we didn't mention is I think that unreliable speed as well. And what did they? How I didn't know that. Yeah, so obviously, the probes probes full of ashes. Well, yeah, say it makes sense. They had to realise the engines that to 270 knots or something and want it.

47:29

That's been indicated. 301 said 250. Wow. Yes, it hadn't reliable speed as well. And so I think the checklist that we have also guides you into potential and reliable or looking for a while. Yes. I think it does actually I do recall that. Yeah so but all in a day's work moody like just hope you're not too just you know was it.

47:49

Hope you're not you too much to stress the United stress. Yeah. We're just dealing with four engine failures and on reliable speed at the moment. When I first heard him, say that all four angels fell. I thought, what I say that, I just say, we've got problems. No problem with our engines.

48:04

I don't know. He's just like a bit of a character today. He's, I like him. He spoke it, thats before lots of different ways. Yeah. So lucky and then I guess David is slowly. Maybe learnt a lot from from that and then overreacted when the Icelandic volcano happened? Yeah, because I think they used like a nuclear fallout models, okay?

49:20

How particle spread. Okay. But they were maybe cautious though they weren't suitable or something like that and so they just grounded all. Aviation everything, go grand. They lie, this will gone from time. Yeah, yeah. And now and that time they theorize putting pods on aircraft and stuff to detect ash particles and things like that so you can find in them, but a lot of airlines fly in the shadow of volcanoes.

49:41

I mean we fly into Naples. Yeah. Sorry that's dormant, isn't it? And into call it sicily Sicily. Yeah. Okay. Name of the volcano. That's embarrassing. The airport of the volcano the airport. Yes. Anyway just escapes there's plenty of volcanoes around the world where including in Jakarta and you know what?

50:08

The most volcanic areas, the Pacific Rim, yeah, is basically the the line that all their aircraft travel on. Yeah. Fly around the Pacific. Yeah. Right over these volcanoes. 

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the end.

So maybe that was a introduction to the jet engine. Yeah I feel like we could do more maybe some. Yeah I think the practical stuff probably more interesting from us about how the pilot took you know things about the engine and but maybe you could do a whole podcast on your your childhood basically visiting Rolls-Royce because that's how it's interesting.

50:41

I just need to get engineers. Awesome. Yeah and I like you to go into the museum and you could the the dark which was one of the first jet engines was a turbo prop and you could touch the in the back of the engine. You put your hand in and you I put your finger on there, one of the turbine.

51:01

Yeah. Sections and move it with one finger and this giant propeller on the front. I mean, it's huge right? Would like move, you know? Feet. Yeah. Because even sat in this museum for years, it's so well engineered like without any oil in it. Yeah, you know, I mean and that's one of the that's like the first ever change in the Dart was like, really, really early on.

51:20

Yeah. So I don't know, if a pilot ever will be the person to do justice to a jet engine. Our job is to just take it for granted. Yeah, yeah. And let's yeah, literally moves a lever that makes it faster. Yeah. And I like the noise but that'll probably disappear as well gets.

51:40

Well, that's it for this one. Thanks for listening. Bye.

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Adam Howey
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