tolipanebas, the guy is asking a genuine question. Yes he/she may be sitting his ATPL, but he/she may never have been in the pointy end of an 8.6psi can, let alone sat there staring at the cabin diff. dial for hours on end. Try asking 10 ATPL holder who have never been out of a light piston what the typical operating pressure of a hydraulic system is. Should we throw stones at those who don't know the answer?
Wind it in a notch son, not every one can be as good as you.