<<I removed all hydraulic components and had my hydraulic shop at work check out the switches and actuators. All good except hi pressure switch was switching high off-scale. Nose gear actuator was allowing fluid past the piston. I suspect that actuator was responsible for the incident and that the switch was the root cause of the nose actuator failure.>>
<<How did the nose gear gas strut (spring) check out - 100# of force?>>
Naf,
A few more things to check:
1. The maximum obtainable system pressure is set by the relief valves inside the hydraulic pump. The relief valve protects all components from over-pressure in case something causes the pump to run continuously or thermal expansion etc. The relief valve should be set a few hundred psi above the nominal operating pressure. I have tested our cylinders to over 2000 psi. The pump is, however, capable of much more so the relief valve needs to be set properly.
2. There are two paths for fluid to get past the piston: The main piston seal and a sealing washer under the nut. Leaks past the main seal tend to via scratches in the cylinder walls. These leaks can range in severity - bleed down in minutes, hours or days.
Failure of the sealing washer is a bit more dramatic. It can flow a relatively large amount of fluid and cause the pump to run continuously. The sealing washers are probably missed during many rebuilds since they are not visible upon initial disassembly of the cylinders and they are not included in the seal kits from Lancair.
Chris Zavatson
N91CZ
360 std.