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For Starter and air control valve operational check, WE connect a gauge with a tee to the Starter sensing line. (SMP515C - SP213)

APU fournish 35 psig

When engine start, WE must observe at the pressure gauge, a pressure between 36.5 and 42 psig.

But i dont know is psig may be inch/Hg ?

Because air pressure is always under this limites.

If is psig what is the problem?

But if it's in/Hg, the pressure is good.

Thanks

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If you're having very specific starting problems, this may be a way to troubleshoot. As long as APU holds pressure above 32psi and start time is between 39 and 61 seconds, there is no reason to do this procedure .....

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On 3/9/2022 at 6:41 AM, pjvr99 said:

If you're having very specific starting problems, this may be a way to troubleshoot. As long as APU holds pressure above 32psi and start time is between 39 and 61 seconds, there is no reason to do this procedure .....

It's not for a specific starting problem but it's planned for maintenance of "C"-Check.

I see in TO for test of Start Valve, with a inlet pressure of 150 PSI, max regulated air pressure is 42 PSI and the mini 36.5 with inlet pressure of 45 PSI.

Not in In/Hg, sure.

We can't have a regulated pressure superior at the inlet pressure.

But actually APU provides a inlet pressure between 30 to 35 PSI, what is the regulated air pressure ? More precisely in the pressure sensing line.

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I understand what you're saying, having read through the card. It just seems that youre trying to do individual component testing on parts that should be checked on a bench. 

 

The only places i know of that uses "hg is the cabin pressure differential, engine lighthouse area and the apu bleed air regulator. All other pressures are psi. 

 

For conversion 14.69psi = 29.91"hg

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15 hours ago, pjvr99 said:

I understand what you're saying, having read through the card. It just seems that youre trying to do individual component testing on parts that should be checked on a bench. 

 

The only places i know of that uses "hg is the cabin pressure differential, engine lighthouse area and the apu bleed air regulator. All other pressures are psi. 

 

For conversion 14.69psi = 29.91"hg

I understand, it's not in "Hg.

I want just to have the pressure values for a inlet pressure (between 30 to 35 PSI) of APU, like asked in the work card.

I think the values of card are false for application on aircraft.

I researche the limits values in the pressure sensing line when start engine with APU ?

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Ok, we hooked up the starter air duct and starter sensing line to the scav filter in and outlet transducers. We use an AM32A-60A power unit to start the engine. In the first vid, we just motor the engine over to maximum rpm. In the second, it is a full start to lowspeed ground idle .....

I dont really see how a sensing line pressure equal to the delivery pressure is possible. I suspect the 36.5 to 42 psi may be from using engine pressure of 70 to 80psi, with the starter valve modulating the pressure to 36 to 42psi ....

In other words, the SP213 card may be wrong. Hope this helps ....

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