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teopereira

Engine start: no APU bleed, no fuel, but N2 keeps speed?

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How it that possible? No APU bleed, no fuel, but N2 keeps speed?

 

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Teo Halfen

 

Windows 10 Pro 64 bits, P3D V4, GTX 1080 Asus Strix, i7 4790K, Asus Maximus VII Hero, H100i, Hd SSD 240 Gb, Corsair Vengeance 16Gb 2400Mhz

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I think he's asking how it spins up without any air source.

 

Dave

That's it!


Teo Halfen

 

Windows 10 Pro 64 bits, P3D V4, GTX 1080 Asus Strix, i7 4790K, Asus Maximus VII Hero, H100i, Hd SSD 240 Gb, Corsair Vengeance 16Gb 2400Mhz

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That's probably a legitimate bug. Submit a ticket.


--Peter Fabian 
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Maybe windmilling! Starter switch (on) activate some elec. power for the display etc.

Regards

Jovabra

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If you can reproduce it, send a ticket at support.precisionmanuals.com


Name available upon request


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I just tried this and I could not reproduce it. With the APU bleed off and do duct pressure, attempting an engine start resulted in no N2 or N1 rotation.

 

Dave


Dave Paige

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I just tried this and I could not reproduce it. With the APU bleed off and do duct pressure, attempting an engine start resulted in no N2 or N1 rotation.

 

Dave

Just do the normal procedure to engine start: APU bleed on, packs off etc... When N2 reaches 23% or whatever close the APU bleed... The N2 will remain where it is, it won't slow down and stop. 


Teo Halfen

 

Windows 10 Pro 64 bits, P3D V4, GTX 1080 Asus Strix, i7 4790K, Asus Maximus VII Hero, H100i, Hd SSD 240 Gb, Corsair Vengeance 16Gb 2400Mhz

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Teo;

 

Ok now that you've mentioned the exact steps, I can reproduce what you have described. So it does appear to be a bug and I would submit a support ticket. After confirming that the engine was not going to spin down, I did move the starter switch to off and the engine then did spin down. To me, this is a very minor issue since I don't know why you'd do as you describe. Normally you'd either just go ahead and start the engine or, if you decide to abort the start, just move the starter switch to off. Not sure why you'd ever turn off the APU bleed at that point. But good find.

 

Dave


Dave Paige

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The engine is not started in the OP's picture. And that's his point, why is it still motoring with no fuel and no air source?

 

Dave


Dave Paige

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J

 

Teo;

 

Not sure why you'd ever turn off the APU bleed at that point. But good find.

 

Dave

I didn't know whether it was a bug or something that for some reason worked that way in the real thing. So it seems to be a bug.

 

Thanks


Teo Halfen

 

Windows 10 Pro 64 bits, P3D V4, GTX 1080 Asus Strix, i7 4790K, Asus Maximus VII Hero, H100i, Hd SSD 240 Gb, Corsair Vengeance 16Gb 2400Mhz

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Er, if the engine is started isn't the APU unneeded at that point?

The engine isn't started, it's cranking over with no ignition and no air source. It could happen in real life if the APU failed during engine start before light off but in that case the engine N2 would run down to zero and the start valve would close.

 

The start valve needs air pressure to open. If air pressure is lost it should close.


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