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After over a year
rennovating, I am hopefully in sight of flying again.
Need some help from
wiser heads on my gear system. Situation:
- Lancair 320 small
tail, 18 years old.
-
New
hydraulic pack factor adjusted to max pressures of 1300psi up / 800psi
down
-
New style
factory preset pressure switches 1100 up / 550 down
- Many hoses
replaced with fresh hosing, most fluid drained from system prior to
testing
- Tested 20 cycles
hoping to purge all air - don't think that worked
The good:
- Everything swings
easily by hand with the pressure dump valve in the dump position.
- Running the pump
with pressure switches bypassed results in 6-8 second activation time until pump
labors, with sequence valves operating as expected and doors closing
flush
- There are no signs
of leaks
The
bad:
- With the pressure
switches installed in the circuit, the pump cycles MANY times to reach full
retraction and even a few times to reach full extension (rather than a nice
continuous run to shut-off)
- Once retracted or
extended, switch cycles VERY quickly (I think this means bypass /check valves
are set too low or air compressibility in line)
- Once retracted and
pump manually turned off, pressure slowly bleeds (same as above, I suspect
bypass / check valves set too low or air compressibility in
line)
- System just seems
like there must be a LOT of air in it which rapidly compresses then slowly
pushes the gear in the intended direction
I can verify the
check valve pressures with a mechanical pressure gage, ran out of time but am
comfortable that I can resolve check / bypass valve issues.
Questions:
- Can anyone verify
(or refute) my theory about the rapid switch cycling at full extension /
retraction? If not check valves, solution?
- Does anyone know
of a good way to completely purge the system of air?
- Has anyone
determined conclusively that the "recommended" pressures of 1100/550 simply
AREN'T enough?
- How high is safe
for the system if I go up on either of the pressure
switches?
My prior plane was a
235 with a virtually identical system (I did not build either one) and, although
it might cycle once or twice at the end of the retract cycle would then
immediately be quiet (although on a very long flight it might "burp" once or
twice in the up direction to maintain up pressure).
All help
appreciated!
Cheers,
Bill
Reister
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