On my fourth test flight I tested the normal and emergency gear
extension/retraction and everything worked fine. My first landing attempt
resulted in a go-around due to gusty winds. When I extended the gear again
on downwind nothing happened. After a few seconds of head-scratching I
momentarily cracked the dump valve. That fixed the problem and the landing
was uneventful (if a bit firm). http://www.youtube.com/watch?v=fo1qnhBuqS8 The
attached JPG file shows the up and down hydraulic pressure readings
throughout the flight. The x-axis is time, with the flight beginning at
20:32Z and ending at 21:12Z. You can see the gear retraction tests
beginning around 20:43 and 3500' altitude. Notice that after the last test
the down pressure remains around 500psi for about 90 seconds even though
the gear is retracted. The up pressure fluctuates a bit then the down
pressure drops to near zero. The bottom graph is a closer view of
the landing sequence. The go-around occurs at 21:05Z. When I retracted the
gear the up pressure went to 950psi as expected, but the down pressure
fluctuated around 500psi. This kept the down pressure switch open,
preventing gear extension. Does anyone have an idea as to what's
causing the pressure buildup on the down side? Thanks, Adam
Molny N181AM 6.1hrs hobbs time
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