Bob Belshe asks:

> While we are talking about flap relays, why do you think the Lancair
> manual design uses the second (redundant) pole on the flap switch?

In the standard system, failure of a limit switch or relay in the
closed position will cause the motor to overrun. Having the power to
the motor also switched gives a second way to interrupt the current
to the motor. That also provides some protection against an allen
wrench dropped into the armrest panel where it might accidentally
short out a relay contact.

> Personally, I don't see any advantage to going to a solid-state
> relay system. With diode snubbers, the original relays seem to be
> pretty reliable.

Do you mean thousand-hour MTBF reliable, ten-thousand hours?
Certainly the diode snubbers will reduce contact arcing.
But a properly-designed and installed solid-state switch
will outlast a properly-designed and installed relay.
That said, I have not chosen to retrofit my airframe.
I still have relays, and plenty of other fish to fry....
like nylaflow brake lines and tiny slow leaks on all the
19 year-old hydraulic cylinders.