ORIGINAL: aaflyer
Ok, I have a simple air up/air down system. BV Retract Valve. Air up to 100 psi Gear Down very slow leak. Gear Up leak is much faster. I have checked all T's and connections I can get to. Should I suspect the air cylinders? I swapped out retract valves same story.
One quick way to find it is to put a forceps or clamp on each line in turn until the leak goes away. That is the easiest way to isolate the problem without starting to take things apart. I usually start with the lines up by the valve and localize it to gear up, gear down, nose gear, mains, and then when it is debugged to this point, I check each cylinder individually. If you have doors, work those lines up by the valves too and then back to the cylinders.
You might find a quiet place and air the system up to around 120 psi and maybe you will get lucky and hear the leak too. This occasionally works if the leak is fast. Wiggle the struts ... some times the leak is only evident when they are moved a certain way.
It is a good suggestion to check all the cylinders before installation and the robart hand pump is one of the most used tools in my shop.