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ATM issue


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OK we need a little more info....

Starting with GCT air right?

2,3,and 4 start ok?

Air pressure dropping off?(to what? is it less than 22)

If 2,3,4, start ok then stop looking at your ATM and move on.

Start with your #1 engine bleed air system. Good bleed air check with just #1 engine BA valve open? If so then look at the starter blast tube make sure its not leaking (should get a Nacelle overheat light if it is (*SHOULD) If it looks good look at your start control valve.

Sounds like it may not be regulating just staying open. Bleed air pressure will bleed off and your ATM will hold for aprox 5 secs then drop off line. (You should be able to hear it degrade)

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Man, thanks! Yeah, bleed air pressure is fine. And its only #1 that does it. So man, thank you again! But heres the thing, there’s actually 2 problems; that was the first one. The second is, when we run the atm by way of the gtc and turn on the hydro aux pump, the atm shuts off. Now, we can have the aux pump on and then turn on the atm and everything is perfect! Also, we have to reset the atm gen every time we turn it on. With the atm on, before the aux pump is on, freqs and volts are good then, obviously, the pump is turned on, atm shuts off, no freqs or volts. weve exhausted all our ideas. were thinking maybe the aux pump?

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Sounds like an OLD F model!!!

Sounds like a bad PMG in the ATM gen.. No excitation to the VR during initial startup. (VR dosent know the generator is rotating) Reset starts the generation cycle (PMG should do this.) (Bad Generator but I wouldnt change it for that...)

ATM and Aux pump always had issues!!! Very large draw not a lot of output. Watch and see what your Volts drop to. The ATM will try and hold (5 secs) but draw is too great and the GCP says NOPE and goes OFF line!!! (if the time frame is wrong (less) swap the GCP and see what happens.

Then (bad PMG) NO excitation to the VR during initial ATM startup and you have to reset. MAD circle you got there!!!

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  • 7 months later...

Sometimes techniques are bad, but then again. Old A mod. prob. B/F #3 eng. start the ATM would drop off line, by depressing the hot day start and going to reset on the A/C gen everything came back. Doing an end around the RCR.

Not a common practice but got you going with bad guys comming over the fence.


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