Wiring runs

RVNewsletter · Post by **RVNewsletter** » Sun Nov 30, 2008 11:01 am

... specifically, penetrating the bulkhead. Those of us with manual trim cables lose one pathway. And the other one (through the vertical rib/705 is pretty small. Is there any problem with just drilling another hole in the 705 bulkhead to run wires forward or is there a significant structural question here?

Post by **bullojm1** » Sun Nov 30, 2008 12:16 pm

Bob,

I would saw your fine putting another small 5/8" hole under one of the already drilled ones (between the bottom two AN4 rivets attaching the F-727 floor rib) without a problem. I believe there is plenty of reinforcement here. Obviously, for the official answer, don't take my word and call up Van's. I have a strange feeling they will tell you the same thing.

Have you riveted your floor down yet? If not, why not run some conduit runs there instead?

RVNewsletter · Post by **RVNewsletter** » Sun Nov 30, 2008 12:25 pm

I haven't riveted down the floors. in fact, I've used nutplates on all the floors (although I did rivet the very aft end of the baggage floors). I have no problem with running conduit there, although I still need to get through the 705 (I think the rear spar wing attach 'fork" comes into play there somewhere). Looking at these wiring run diagrams from Van's, I also wonder about getting wires through the 704 main spar.

BTW, one question I think I asked earlier about strobe wires out to the wing. If I add a wing root connection, what do I do with the shield drain wire?

cjensen · Post by **cjensen** » Sun Nov 30, 2008 12:40 pm

I have two holes in the 708, 707, 706, 705 and 704 bulkheads. I called Van's about it last year, and they said it makes no difference. They said some people have four or five in the 704, but there's only really room for two in the 705.

Post by **bullojm1** » Sun Nov 30, 2008 1:38 pm

Bob,

I put three whopping big 3/4" holes in the F-705 bulkhead. The F-705 is so thin I can't imagine it having any structural impact. I like running the wires here much better than the center section because of the less chance of interference with the elevator pushrod. I know Checkoway (sorry to bring up that name to you!) made the same 3/4" hole in his F-705 and his airplane has over 1700 hour on it.

As far as the F-704 goes, your fine putting an extra hole or two in the webbing (thin part) according to Van's. Most of the load goes through the top and bottom thick bars. Checkoway (sorry again!!!) and Richard Horan both put holes in theirs. Checkoway put a fairly large hole in the center of it, while Richard (http://rvproject.co.uk/Systems/210708_Spar_drilling.htm) put a smaller 5/8" or so hole on the sides, above where the other holes are. You can find details on their respective websites.

As far as the shielding question goes, The shielding drain wire should be in the connector so the wing portion of the shielded wire is grounded. Do they make shielded 3 conductor connectors? If so, that would be the cat's meow so you don't bleed any RF interference out of a nonshielded connectors. However, I don't think it will be that much RF interference because basically you have all the metal in that immediate area as a shield of sorts.

RVNewsletter · Post by **RVNewsletter** » Mon Dec 01, 2008 8:15 am

Where's you put the 3/4" hole, near the center tunnel or did you run it up under the baggage floor? The latter seems like a good route for the strobe wires to the wings (My power pack is behind the baggage bulkhead) leaving the center section there for the tail light and ELT (and flap) wires to go up the center section.

BTW, I don't have a problem with Checkoway per se. He had a great site and appears to have a good life. I do have a problem with his making stuff up about me to make a point while selling an article to Kitplanes and I do have a problem with his "I built it this way and I'm this way so you have to be like me, too."

He's a dual income-no kids guy which is fine, but he lacks knowledge about people who aren't in that situation and shouldn't assume an expertise he doesn't have.

But that's another thread...

cjensen · Post by **cjensen** » Mon Dec 01, 2008 9:16 am

RVNewsletter wrote:Where's you put the 3/4" hole, near the center tunnel or did you run it up under the baggage floor? The latter seems like a good route for the strobe wires to the wings (My power pack is behind the baggage bulkhead) leaving the center section there for the tail light and ELT (and flap) wires to go up the center section.

I put the 3/4" hole along the top right of the tunnel. I don't have anything running or mounted under the seat pans or baggage floors. My wiring situation is a bit different...at least for now. I don't have any lights or strobe wires that need to run to the tail. I have provisions for it, but they won't be installed for now.

RVNewsletter · Post by **RVNewsletter** » Mon Dec 01, 2008 9:45 am

I'm going at it backwards (literally, it seems) because if I can get the strobe and ELT taken care of, I can probably go ahead and rivet on the aft top skin and make it look more like an airplane, reducing -- perhaps -- the number of people who stop by the hangar and say, "doesn't look like you've done much since the last time I was here."

Post by **bullojm1** » Mon Dec 01, 2008 9:51 am

Bob,

Here is where I put my 3/4" holes for the conduit:

And the finished product with the conduit: