Hi all, a trend is spreading in our company to save APU's life
:
the goal is to not allow big fluctuations in the APU Egt while starting the engines: instead of doing standard good procedures, it goes as follows:
You call "Before start cklist below the line
except packs".
You check starting pressure above 30, but not the real unloaded pressure, then you turn the pack off and immediately open the start valve.
Also, immediately after starter cutout, you open the other engine's start valve. Immediately, at the speed of light.
So the APU delivers a constant flow and the Egt doesn't fluctuate.
I'd like to know if others do this, as I have some concerns regarding this procedure:
I have always watched carefully the unloaded pressure to crosscheck and confirm the closure of the start valve.
Doing this procedure so quickly doesn't allow to make a good crosscheck.
Also, I'd like to know if the START VALVE OPEN is an indication of valve position alone, or if it gets information from a pressure switch, like somebody says.
Comments? Thankyou