Master and starter relays

Flying Scotsman · #1 12-05-2010, 08:25 PM

The plans call for these two to be mounted right underneath the battery, screwed into platenuts on the two stiffeners and a backing plate. Problem is...I don't think they're going to fit there. There's *just barely* not enough room because the doubler plate for the fuel line (positioned exactly according to plans). I really don't want to take that off...it's riveted in, hard to reach now to drill out, painted, and sealed with RectorSeal. In short, a mess to take off and trim.

I'm thinking of a doubler plate (layered, actually, 4" x 6" .063, 2" x 4" .032) on the firewall, just below and right of the battery (looking forward).

Anyone else have this problem? Anyone have any other ideas for mounting these dudes? Trying to keep wires shorts, obviously, but also accessible.

Thanks...

Steve

f1rocket · #2 12-06-2010, 04:40 AM

I can't view your pictures from work but typically, you want the master solenoid as close to the battery as practical and the starter solenoid where it is convenient. It can go anywhere really. Put them where you can get at them and continue to move forward.

apkp777 · #3 12-06-2010, 06:29 AM

Steve,

What type of plane is it?

Noah · #4 12-06-2010, 10:50 AM

Steve, I didn't have any issues mounting these, and all of my stuff was mounted per plans. I don't recall how close these items were to the fuel line feedthru.

One other thing to consider is whether you will need a starter contactor on the firewall. The Skyweight starters have a solenoid that is jumpered, but the way it was intended to work is that when the pinion gear engages, the contacts close and the motor starts. If you look at the wiring diagram for the starter, they advise removing the jumper in experimental installations and wiring the starter switch directly to the starter, eliminating the contactor on the f'wall. In certified installations, the STC does not allow removing the start contactor from the A/C. One disadvantage of wiring this way is that the starter cable is always hot. One advantage is that the installation is simpler and lower weight with fewer components.

I didn't realize this when I built mine, just built it per plans. I could go back and change it but probably won't since it is all wired.

Bob Axsom · #5 12-07-2010, 01:26 AM

No Instructions for such items on my RV-6A and I don't know what type of airplane you are building but I just looked for a good mounting surface near the battery. The battery is on the floor center up against the firewall. I installed the two units on opposite sides of the left of three structural members running from the firewall to the instrument panel under the fwd upper fuselage skin. No problems in 600 hrs of operation.

Bob Axsom