Ray Allen Trim Wiring

[Weasel]

The Ray Allen stick grip trim switch system has individual single pole double throw switches used (one for up and one for down) to control the trim servo.

The switches are rated so that they can be used in a single (pilot only) control setup to handle the trim motor load without the need of a relay.

The documentation goes on to say that in a duel ( pilot and co-pilot) control system, the relays are necessary.

My question is why to we have to have relays with the duel control setup?

I have my trim wiring like this:

The Power symbol has a + on the top and - on the bottom....its hard to read.



Am I missing something?

[Mich48041]

My first thought was what would happen if the pilot pushed up trim and copilot pushed down trim at the same time. Would a fuse blow? Then I studied your wiring diagram and could not see any way that there could be a short circuit, unless I am missing something. Even if the pilot pressed up while the copilot pressed down, or vice versa, the trim will not work, but there will be no short circuit. Did you design that circuit yourself? If so, good job! You might consider a trim-disable switch in case a switch gets stuck.

[Weasel]

Yes I designed it and have operated it in the RV-10 for over 600hrs. No problems. I was working on one the other day and it refreshed my memory on the subject. Thought maybe there is something I am missing.

[Mich48041]

I redrew your electrical drawing as a downloadable pdf.
And I put your name on it to give you credit. Hope that is OK.
Would it be alright if I shared your circuit on Matronics AeroElectric List?

[Weasel]

That is fine with me. Hope it helps someone.

[Mich48041]

Joel, I posted your circuit on the AeroElectric List along with words of praise.
In case of a runaway trim caused by a stuck switch or suicidal copilot, the opposite
direction button can be pressed and held until the fuse or breaker can be pulled.

[DaleB]

The only issue I see is if you plan to make the copilot stick removable. I am thinking of a DB9 connector for the right side stick... I'd need a jumper plug to take its place. Other than that, it looks good to me.

[GalinHdz]

Another issue I see is that without the relays you can't isolate the pilot flying (PF) trim control from the pilot not flying (PNF) trim control. With relays you can deactivate the trim control of the PNF so that he can't accidentally change the trim.

Otherwise the circuit is excellent and keeps with the KIS (Keep It Simple) principal.

[sglynn]

Check out Vertical Power. WIth it you don't need the relays and wiring is way simplier. This is just one of many benefits.
http://www.aircraftspruce.com/catalo...clickkey=12347

[Raymo]

Originally Posted by GalinHdz

Another issue I see is that without the relays you can't isolate the pilot flying (PF) trim control from the pilot not flying (PNF) trim control. With relays you can deactivate the trim control of the PNF so that he can't accidentally change the trim.

Otherwise the circuit is excellent and keeps with the KIS (Keep It Simple) principal.

A custom jumper plug could be used to bypass the co-pilot stick, installed or not.