1. Is the pump supposed to make a very high
pitch squeal?
If not what would cause it? The sound is
almost unbearable.
The fluid tank was 3/4 full before priming
and was about 1/2
full after.
A: The pump is very noisy when operating, although I
wouldn't call the "normal" sound a squeal. Other opinions about
this? The fluid drop sounds about right, and equates to the volume of the
lines and actuators--about one quart. Once the system is filled (be
sure to also purge the emergency gear pump circuit by lowering
the gear using the hand pump), the fluid level should remain almost
constant.
2. The main gear don't go up and down
together. The left gear
is always first up followed closely by the
right. Coming down
the left goes down and locked even before the
right leaves the
wheel well. Should both of the mains
be going up and down
together.
A: There is no "linkage" that will cause the gear to move
together. Most I've seen don't move together, but are much closer together
than yours. The gear with the lowest operating friction will move
first/fastest--both up and down. It sounds like you may have some
binding on the right main gear. Based on your description, I'd look
closely at the gear door/slider area to see if the door is holding the
gear up "unnaturally." One test that you can use to check this
is to start with the gear retracted, turn off the master switch or pull
the hyd pump circuit breaker, and then cycle the flaps to bleed down
the hydraulic pressure. At some point during this process, both mains should
"free fall" out of the fuselage to a dangle position. If they don't, select
the gear lever to down. If both gear don't fall to the dangle position (will
need wheels and brake assemblies installed to sufficiently weight the gear for
this test), you have excessive binding in the pivots/doors/actuating
cylinders that needs to be corrected. One easy check/adjustment is the
pressure plate on top of the rack gear that operates against the drum gear on
the main pivot, but your description above points to a hang-up with the gear
doors as the most likely culprit.
3. The pump runs for about 10 - 15 seconds
after the gear is up.
A: This is normal. Operation of the gear uses all the fluid
stored (under pressure) in the accumulator, causing the hydraulic
system pressure to drop well before the gear gets to its commanded
position. This causes the pressure switch to turn the pump on, and it
essentially "pumps" the gear into position. Since it takes only about 500 PSI
to move the gear to the fully retracted position, the gear gets to the
stops before the system pressure is fully restored. As soon as the
gear hits the nylon up-stops, fluid starts flowing back into
the accumulator, and continues until system pressure reaches the switch
shut-off pressure--approximately 900 to 1000 PSI. The system is now restored for operation of the gear (again) or
the flaps.
4. The flap accuator is very touchy in the off
positon. Wiggling
seems to help keeping the flaps up and to stop
them from
creeping back down.
A: The flap actuator is almost certainly not moving to the correct
up/off position. This is a common problem, more with the
gear actuator than the flap, but it can happen to either. Test this
by taking the front panel face off the actuator so you can move the
actuator just a bit further up (or down) to see if this corrects the
problem. If it does, elongate the slots and you're fixed. One thing
that sometimes causes this problem is having the face plate spaced away
from the actuator main body, effectively shortening the available "throw" of
the levers. If it's not flat against the actuator body, try fixing this first
(the thickness of the fiberglass vertical panel between the plate and the
actuator body is enough to cause this problem).
Any advice would be greatly
appreciated.
Hope this helps. Bob
Pastusek