Posted for "Mark Ravinski" <mjrav@comcast.net>:

I've had some sort of vapor lock occur when the (RED) aircraft is parked in
the hot sun all day.
The gear is down but both pressure switches become activated and the system
locks.
The first time it happened after being at a fly-in all day the gear wouldn't
retract.  Opening the dump valve did nothing to help.  I had to return to
the field and do some serious problem solving.
The only way I found to correct it is to open the hydraulic system at any
fitting and release the pressure.
A squirt of fluid and everything goes back to normal.

It has happened the other way a couple of times also - failure to extend
after a long leg.  In this case the dump valve works.
It's a good reason to make those gear checks on final.

Fly safe.
Mark Ravinski
N360KB 1280 hrs