Yellow hyd A320

[whitelabel]

Guys just a quick and simple question. In-flight on the system page the hyd fluid quantity in the yellow system is always indicating much higher than on the ground. Sometimes even just until underneath the fire shut off valve. I can guess but can someone tell us the reason?

Many thanks guys (and girls)

[Valmont]

"HYD: A slight decrease in quantity is normal.
Fluid contraction during cold soak can be expected.
Green system is lower than on ground, following landing gear retraction"

PRO-NOR-SOP-15

[Goldenrivett]

Hi whitelabel,

I assume the cargo doors were open when you looked at the Y Hyd fluid level when on the ground. Some Y Sys fluid was in the door jacks when they were extended. When the cargo doors are closed, the jacks retract and the fluid is returned to the reservoir.

[whitelabel]

Thanks guys. Cant remember if the cargo doors where open. I know green will be lower in-flight due to gear. Blue remains pretty much the same and yelloe increases. Might indeed have something to do with doors. I will have a closer look on my next flight.

[EGMC]

I have also on one aircraft seen very high levels, it was in-flight and looked deeply into FCOM and there was no limit so wasn't concerned any.... just curious..... looking for a simple explanation like gear with Green.