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Matt,

I've had two occasions where my gear didn't come up.  Two system problems
may be involved.  The pressure switch and / or a failed intermittant duty
relay.

The first time I was on the road and sparked across the up hydraulic
pressure switch with a screwdriver (airborne as I had no jacks) thus
bypassing the switch.  This churped the pump and subsequently all worked
fine.  Although I've not since replaced the switch these switches have been
known to occasionally fail.

The second time (I had jacks) the intermittant duty relay had failed
(fried).  This was due to extended duration flight with the CB pulled. In my
plane the 50 amp CB does not isolate the relay control power; just the high
current hyd. pump power.  Therefore the relay was actuated (unfortunately)
the whole time I had the CB pulled.  A secondary issue was an internal
hydraulic fluid leak causing the pump to cycle intermittantly (thus
prompting me to pull the breaker).  It turns out the dump valve (designed at
600psig) is undersized (hello- this should've been self evident) and had an
internal leak.  I replaced the both valve (with a 2500 psig valve (i think))
and the relay and now all is well. Total cost - about $30.

Good Luck,

Larry Henney

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Please send your photos and drawings to marvkaye@olsusa.com.
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