Adam--

Thanks for the informative .pdf ! The diagram on page 3 shows the proper way to protect the hydraulic pump relay contacts with the large MOVs from each pump motor lead to ground. (The smaller MOVs are used to protect the pressure switch contacts if you don't have diodes built in to your relays.) I used the largest MOVs I could find on the motor leads, but can't recall if they were 14.5V or 18V. The varistor voltage of these devices is specified +/-10%, so I might have used the 18V devices just to be on the safe side. The "Maximum Operating Voltage" should be at least 10% higher than your buss voltage (13.2V?) , or at least 14.5V for a 12V system.  I'll retrieve the exact part numbers I installed tomorrow when I go to the hangar.

MOV [Metal Oxide Varistor] is a generic term; The ones I used were Panasonic ZNRs [Zinc-oxide Non-Linear Resistors] that I ordered from Digikey.com.  - Digi-Key offers a short training module for Panasonic ZNRs at: http://dkc1.digikey.com/us/en/tod/Panasonic/ZNR/ZNR.html . Also, there's a pretty good (simple) tutorial on using MOVs to protect switches controlling inductive loads at http://www.progeny.co.uk/Back-EMF-Suppression.aspx

Regarding the gear transition light, I used two individual diodes at the pump rather than the bridge rectifier. For my gear transition light, I used a red/green bi-color LED. It glows red when the pump is running (in either direction), and turns green when the nose gear door closes. I did that because there have been a number of reports where a nose wheel became cocked sideways on liftoff, preventing the nose gear from fully retracting. If my gear transition light doesn't turn green after gear retraction, I'll know I have a problem up front. I'll post the circuit diagram in a day or two; It only takes four resistors, a bi-color LED, and a microswitch on the NLG door.