'Splain this
 

Nothing to do with models but ever since I saw this on the news a week or so ago, I've been wondering...an airliner made an emergency landing due to smoke from one of the engines getting in the cockpit. How does smoke from an engine get into the cockpit with all the engines with which I am familiar being on the wings or the rear to middle of fuselage? And all the cockpits I know of are on the very front of the plane. How could it get there and why wouldn't it get in the passenger cabin too?

The good news was no one injured.

Larry

RE: 'Splain this
 

It was a Geebee wasn't it?????

RE: 'Splain this
 

What kind of plane was it? More than likely, they meant cabin, not cockpit. The news crews are great at saying things that are not true. I can see it filling the cabin, but if it got to the cockpit, the cabin would have a lot of smoke.

RE: 'Splain this
 

Can't trust the news when it comes to explaining aircraft issues. Was it a DC-3 that lost a cylinder and they had the window open and the prop feathered? Or it could have been a multiple of problems where they had an electrical malfunction that caused a short creating smoke and then the lose of an engine at the same time. Who knows until the NTSB report comes out.

If it was a jet liner with an engine fire and smoke from the fire reached the cabin or flightdeck, then a very large fireball would follow since the gas tanks are between the fuse and the engine.

RE: 'Splain this
 

Jets use engine bleed air from the engine compressor section. This can be hi or low pressure. It's routed through the fuselage to just under the wings into the air conditioning system. It runs a turbo compressor and does all sorts of fancy things to pressurize the cabin. There isn't a single source for cockpit or cabin air. The air coming out of the air conditioning system can be quite cool and is sometimes mixed with bleed air to make it warm. If an engine has a bearing failure, it makes smoke. The smoke gets mixed in with the air that's being used to warm the air coming into the cabin. Oversimplified explanation, but there you have it.

Dan

RE: 'Splain this
 

Boeing767PF I was going to say the exact same thing. Bleed air is way most jet airliners pressurize, heat, and cool, so technically any smoke in the compressor section of the engine could potentially enter the cabin/flightdeck through these three systems.







No1RCfan,
RC enthusiast
A&P

RE: 'Splain this
 

We had an air cycle machine go bad one time in a commander. Man, did it get hot in there fast. Had to stay above 140 I think it was to keep it off, slower than that, and it filled the cabin with smoke and heat. Fun stuff

RE: 'Splain this
 

I'll chime in here with a little more technical info. Hope you can follow. The above is correct though!
First of all, all jet aircraft that are pressurized use bleed air tapped off of the engines at different stages before combustion. You have low pressure and high pressure. Usually when the aircraft is at idle or low power settings, air is taken from the high pressure stage. As the engine RPM increases, it switches to low pressure. On Learjets we use "Modulating Valves" on older ones, 60's use a "Mixing Valve), and the 45 uses a bunch of different valves to mix air. Here is a little test you can do next time you ride on a commercial aircraft. When you board the aircraft and sit down, turn on the overhead air full blast. When sitting at the gate, the plane usually has the Auxillary/Airborn Power Unit (APU) running. This is essentially a small jet engine that has a generator, hyd pumps, etc hooked to it. It is designed to run at 100% RPM regardless of load. More load more fuel. This is usually the last thing the engineers cram into the aircraft tail or wheel well. They always make it a real ***** to work around. This APU also supplies air to the cabin for that air conditioning your feeling at the gate. This APU also supplies air to the starters on the main engines. When you start the "pushback" and the pilot starts the engines, notice what the air does. It usually stops, as all or most of the air is diverted to the air starter on the engine. Also you'll notice the lights flicker as they bring on the engine generator and split the load between the engine and APU. One other thing that is interesting. The more air you take from the engine, or bleed, the hotter it runs and less power it has. If it is really hot, most likely they shut off the A/C for a few minutes to get the power they need. Also, the same goes for when the weather is bad. If conditions are right and they have to take-off with wing anti-ice on, kiss the a/c good by! When I am trouble shooting problems on engines, I often use the ITT (interstage turbine temp) guage to read what the engine is doing. You can tell so much from this guage. If I have a split between engines, I know one has a leak. Air is leaking from the engine, so usually that means it runs hotter. That is of course if the engines have similar total time on them. We have had several #3 carbon seals go out lately, and you guessed it. The cabin fills up with burning oil smokey stuff. It really scares the passengers and sometimes makes the pilots seat cushions dissappear. Hope this helps. Any other questions and I'd be glad to help!
Nik

RE: 'Splain this
 

Hey Nik, heres one to see if you have seen, Citation jet, holding on the runway, everything normal, add throttle to take off, as we reach max power, the left ITT guage drops to zero. Everything else remains normal. Figuring its the gauge, and the short runway we are on, we continue and in the air, everything on the engine sounds normal, it follows the throttle control. Nothing out of the ordinary. Pressures fine, all other guages normal. Come in for a landing, call the factory to order the guage and they says its not the guage. Any guess as to what we found?

The fix was $250,000.00 if that helps.

RE: 'Splain this
 

Ok well lets see here! Engine was running normal you say and all other gauges were functioning correctly. I'm assuming fuel flow was indicating, otherwise you would not have a running engine. In your situation I would of guessed the gauge too! But since you say it wasn't after the swap then your looking at an ITT harness most likely. Or at least something happened to the harness. Most likely to change that you have to pull the engine. This is all I can hypothesize with out being able to ring the harness out with a meter. If this is not right, dont tell me the answer. By the way what model engine? I might need another hint though if I'm wrong. I might have another guess if this is wrong, but that guess would entail replacing the harness too, along with some T wheels.

RE: 'Splain this
 

When we called pratt, they said, "its not the guage, go look in the front of the engine and tell us what you see". We didn't even have to test anything. It was pretty nasty. Gotta tell you now,

Sucked a piece of fod and it took out 50% of the fan blades, chunks about as big as a quarter to little tiny pieces. What ever hit the ITT sensor tore it right out. The blade parts went back through and ate parts all the way through the engine.

The thing I didn't get is why we didn't get a vibration or any other indication that the engine was coming apart. We flew it for about 15 minutes. All the damage must have been done just as we opened it up on the runway. I had a friend in the back seat that said he thought he heard a weird noise, but thought it was just the engine spooling up. Strange.

Had the same thing happen on a falcon 10 that a friend owns and they didn't loose the front fan, but one of the rear compressor fans. The only indication there of a problem was a nanosecond vibration on start, then everything was normal. They flew it for over a month talking to maint all the time before they flew it down to have it checked by falcon jet.

I would have thought they would shake apart as fast as they spin.