Emergency Shut Down system - Turbine Engines: A Closer Look

[johnofe]

If there was a catastrophic failure of the engine and it exploded under testing (rare, but might happen) and part of the engine hit the manual by-pass tap for the fuel line used in purging, there would be no way of shutting off fuel in a hurry. Have you thought about removing the handle before operation? It's sticking right out and could be easily operated by flying parts (I guess so anyway). This is worse case scenario of course.

[AgentJayZ]

@johnofe There are four valves upstream of the point where the fuel line enters the building, all of which must be open to allow fuel to flow to the engine-control valve.

The ESD system is connected to two of those upstream valves.

[poppyopi]

This great video brought up a question for me... Does that emergency shut down system cut all connections to the engine, or is it some sort of brake system? I'm just wondering, if it was accidently hit during a test, that it could cause damage to the engine (though I'm guessing the button would have a 'break-glass' seal over it, if that was the case).

[AgentJayZ]

@poppyopi The button is out there exposed so there would be no delay in its activation if the decision was made to use it. It releases an air powered deadman switch that holds open the fuel supply valve, immediately upstream of the fuel control valve. If we lost electrical power to the control room, the ESD system would also activate.

Air holds open the fuel valve, and electricity holds the air pressure. Lose electricity or push the button, lose the air, lose the fuel to the engine.

[poppyopi]

@AgentJayZ Thanks for the reply. You explained it all clearly in the video. I just missed the connection with "ESD" and the safety valve that you showed us (I must be dyslexic). I also thought it might be a little more dramatic than just cutting off the fuel.

[AgentJayZ]

@poppyopi The only thing you can cut off is the fuel. Once a turbine engine is running, it no longer needs the ignitors. As explained in other videos, when you see a jet airliner flying overhead, the ignition is turned off.

So that leaves air or fuel. There's no practical way to shut off the air supply to a large jet engine.

So that leaves fuel.

[rotjesenmatjes]

Are you guys not wearing ear protection, or are you using the small plug ear things?

[Wonkabar007]

What would be the worst thing that could happen to a engine on the test bed, they seem so reliable these days ?

[AgentJayZ]

@Wonkabar007 The worst?

... The absolute worst thing possible?

Hmmm... if the earth were to be destroyed by an impact of very large, high speed rocky object which stuck exactly on the bullseye of our test cell....

I'd say that'd have to be the worst... but maybe not, because it'd all be over so quick...

Somewhat less worse would be to spill my coffee on the control panel during a test run...I guess it all depends on a lot of things.

[AgentJayZ]

@Wonkabar007 OK, seriously, the most destructive thing that can happen to a gas turbine engine anywhere is the failure of a turbine disk. Very rare, but a lot of energy imparted to extremely strong parts.

An accident like this happens once in about every ten years amongst all the world's airliners.

[Wonkabar007]

@AgentJayZ Maybe thats what happened to the RR engine on the A380, because lots of bits flew all over the place, putting holes in the wing, I guess that window in your control room is special tough glass.

[AgentJayZ]

@Wonkabar007 I think the Trent had a compressor disc failure, uncontained. That's actually the second worst thing that can happen. It's because turbine discs are much more heavily built than those of the compressor, so there's that much more metal and rotating inertia involved.

The control room window is glass, sandwiched between two layers of Lexan. A turbine disc would go through it like it was paper. That's why the operator is out of the plane of rotation of the turbine.

[Wonkabar007]

@AgentJayZ Thanks for the excellent info.

[1BustedMyth]

Another good one

[cheetawolf]

hopefully we never have to use this button.

*presses it*

thats funny!

yet another great video from one of the few people who do this sort of stuff.