1. Any ideas on why the gear could have come up?  I have not disassembled anything yet or put the plane on jacks.  However, the overcenter links appear fine and recently lubricated, and the springs appear fine (I have the newer style circular springs,not the old screen door springs).  The emergency gear dump was tested several flights (albeit a month ago) and had normal pressure in the nose gas strut.

Clark,

 

Yes, I just helped someone (private e-mails) solve a similar, but slightly different, problem.  Occasionally the gear would fail to come down when he selected DOWN while in flight and he could hear the pump running.  Recycling the gear switch would allow the gear to come down. He could not duplicate the problem while on jacks.

 

Analysis shows that there is a way to provide power to both sides of the pump motor.  The Lancair wiring diagram shows that the indicator light is connected to the (I) post of the intermittent relays and that both relay (I) posts are connected together and run to the panel "gear transition" light.  The (I) post is actually connected to the contactor plate inside the relay.  Selecting one relay draws the contactor to connect the power in and power out posts, thus also providing juice to the (I) post that back feeds to the other relay's contactor plate thru its (I) post.  If the contactor solenoid is sluggish, slightly jammed or cocked, it is possible to supply power to both sides of the pump and the pump will still run in some direction (I discovered this in weird bench tests).  It is possible that even though the DOWN relay was selected, the UP side of the motor was also receiving power thru its relay's contactor plate and the motor chose to run in the up direction, however slowly.

 

Of course, I am assuming that your aircraft power was on.

 

There is a solution that I have repeated every year or so and that Lancair finally implemented in wiring the pump in the Legacy by using small diodes to isolate each (I) post from the other as power is brought to the panel light.  Also, the small current diodes may provide protection to the #20 wire running to the lamp since it is carrying power supplied through the 50 Amp motor circuit breaker and a short in that skinny indicator wire would probably lead to a fire before the 50 amp breaker popped.  I have an inline 3 amp fuse in my transition light circuit in addition to the diodes.

 

Side note:  The relays can get screwed up (no pun intended) if, for whatever reason, aircraft power is on, the motor breaker is pulled, the relay power breaker is left engaged and pressure bleeds down enough to cause one of the intermittent relays to be selected for a long time.  The indicator light will not be on because there is no power across the contactor.  If these relays are left powered for a long enough time, they can fail in strange ways.  One is better off pulling the relay power breaker, thus disallowing any relay to be selected or wiring the relay breaker or fuse after the motor breaker so that pulling the motor breaker completely removes power from the entire hydraulic pump system.

 

Anyway, once the diodes were installed, the other fellow's problem has not occurred again.

 

UP (I)----->|------\__fuse________gear transition light.

DN (I)----->|------/