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Hi Bill,
I had a similar problem when our 320 first flew many years
ago. We did a lot of trouble shooting, including changing out the dump
valve, adding high and low pressure gauges and isolating each actuator
individually (a messy process involving plugs and caps). It turned out to be a
scratch inside one of the gear actuator tubes. When the gear was up, the o-ring
was on a smooth portion of the tube interior and held pressure. When the gear
was down, the o-ring was over the scratch allowing it to leak internally.
Isolating the actuators one at a time would be a logical step in the trouble
shooting process. (buy several caps and plugs and invest in a large supply
of paper towels :-) Hope that this helps.
Bill Harrelson
N5ZQ 320 1,650 hrs
N6ZQ IV under construction
----- Original Message -----
Sent: Monday, June 22, 2009 10:52
PM
Subject: [LML] Hydraulic problem with 320
landing gear -- help wanted!
Intermittent problem: With the landing gear down, my pump will
sometimes run continuously. No problem if the gear is up (just an occasional
chirp). If I pop and reset the circuit breaker, it will often stop
running.
I don't have a pressure gauge to help
troubleshoot.
There are no external leaks.
There are no other
functional problems with the landing gear system.
Since the gear down
is the low pressure side, it seems unlikely that if there was a low to high
leak in a cylinder, that there wouldn't also be a high to low leak with the
gear up.
My gut feeling is that it's an internal cylinder leaks (low to
high), but it doesn't make perfect sense.
Could a faulty pressure
switch on the pump cause a problem like this?
What else could cause
it?
Anyone have a identical problem?
Thanks in advance -- Bill
Kennedy
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