HYP EDP Pump failure issue

[boctal]

The failures for the engine driven (1A and 2A) hydraulic pumps are producing "HYD 1(2) LO PRESS" caution message instantly with pressure still in the normal range and is not producing a "HYD EDP 1(2)A" caution message until 2B is turned on. The HYD EDP 1(2)A message should come on at the time of failure and the HYD 1(2) LO PRESS message should only come up when the pressure falls below normal (green) levels.

Edited January 14, 2022 by boctal

[Keith Smith]

This got me thinking since I have played with the failures a few times. I was able to ask the developer to clarify a few things. It is indeed working as expected. From a pilot perspective, the MOMENT the engine driven pump fails, you'd want to know about it. You would NOT want to learn about it via a low pressure warning after the pressure in the accumulator has already dropped below 1800psi. So, it's a GOOD thing that you get the notification (low pressure) virtually right away. 

If you were to turn 2B to ON (right side electrically driven hyd pump), the system would pressurize and you soon see a HYD EDP 2A warning.

The key element here is that the HYD PRESSURE warning is tied to a low pressure switch near the engine-driven pump. The moment the pump dies, the pressure from the pump goes away very quickly, hence the warning. Hopefully this helps clear it up.

I found a study guide for the Challenger 650 hyd system and is says the warning trip if the 'system pressure' drops below 1800psi. Again, that should not be confused with the pressure at the accumulator, which is what the HYD synaptic page displays.