Using my iPhone I took a video of my pressure gauges while extending my gear on a flight today. It is starting to warm up out here. We're not cooking yet, but it is enough to start observing the hydraulic pressure spike which was the subject of a previous LML thread.
It was a bit bumpy on downwind, but the gauges are still clearly visible in the video.
The high pressure circuit was just a hair under 1,500 psi when gear-down was selected. One can hear the pump fire up and release the gear, The high side pressure begins to drop and then the spike immediately hits the low side. It reached 450 psi in this clip. If the spike reaches the low side pressure switch setting, the pump solenoid will open and the pump will shut down. I have my low side pressure switch set to
800 psi which has proven to be high enough to avoid any gear hesitations and/or extension failures.
Chris Zavatson
N91CZ
360std
www.N91CZ.net