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I finally got the landing gear on my 360 kit to retract. (The delay was self-induced -- I've been doing other things.) I have some findings to report.
Test Configuration:
1) The stub wing skins are not installed. It's much easier to work on the system this way. The sequence valves are temporarily connected via hardlines to the cockpit closeout rib bulkhead T-fittings. The sequence valves are in the back part of the wheel well, and they are not actuated by the gear legs. Obviously, this is not the flight configuration.
2) The hydraulic pump is temporarily attached to the "crosses" on the cockpit floor by flex lines. The hydraulic pump panel (as described in the manual) is mounted to a bookend placed in a convenient location on the cockpit floor. I did this because the bulkhead to which I will permanently mount the hydraulic power panel is not yet installed. Besides, it's much easier to fix wiring mistakes this way (an unanticipated but appreciated benefit...)
3) The rest of the system is in flight configuration, though doors were not attached for the initial runs.
4) The pump was powered by a car battery, attached by jumper cables to 10 AWG pigtails attached to the hydraulic power panel. The system was energized by placing the jumper cable onto the battery terminal.
Findings:
1) It was easy to bleed the system by placing the flex line from the high pressure cross into a plastic bottle. The system is first operated by pressurizing the low pressure side (switch in the "gear down" position), so the fluid comes out of the low pressure port and into the high pressure port.
2) The final position of the gear in the "up" position was different than when cycled by hand. This is because the cylinder stops push against the cylinder ends, which go to a different position when there is 1200 psi in the cylinder. When the cylinder is unpressurized, the end plug on the cylinder is free to move in slightly until the AN fitting hits the edge of the hole in the cylinder outer body.
3) The same holds true for the gear door cylinders. Do the final adjustment after the system is pressurized.
4) The rod ends should be adjusted when the cylinders are pressurized in the "down" position. Charge the system to 500 psi and adjust the rod end until the bolt freely slides thru the rod end and the gear linkage. This ensures that there is no residual pressure on either the nose gear tunnel cover (which has a history of failure due to maladjusted cylinders) or the corresponding part of the main gear system.
5) It is possible, but extremely difficult, to actuate the main gear sequence valves by hand. I would estimate that there is approximately 100 pounds of force required to close the sequence valves, but it's just an estimate.
6) It's a good idea to put a sheet of plastic under the hydraulic pump for these tests. You might also put a garbage bag under the gear wells. (I wish I had...)
WARNING! WARNING! Don't stick your fingers in there with the battery connected! (No, I didn't learn this the hard way.) Pressurize the system, unplug the battery by removing the jumper cable, pulling the circuit breaker, or what have you, and then do your adjustments.
Good luck!
By the way, I have worked on the kit for 450 hours so far, but 30 of these have been on the horizontal tail. This includes only touch labor -- no plans reading, no shopping for tools -- nothin' but "fingers on the parts" time. - Rob Wolf
LML homepage: http://www.olsusa.com/Users/Mkaye/maillist.html
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