Extra holes in Center Section bulkhead now or later?

[Desert Rat]

Hey All-

Vans has a document on the tech Q&A page of their website that maps acceptable locations for optional extra holes in the center section bulkheads for extra wire bundles and whatnot.

I suspect that more optional routing paths are better here and since I'm just now working on the center section it would certainly be easier to poke a few more holes now. But, I'm wondering if it might be better to hold off until further down the road to see exactly where it makes sense to put them, rather than guessing.

What do most people do here, and would you do it again?

[1bigdog]

Hi Terry,

That's where I am now. I waited, mostly because I have a centre console so I can route lots through there but I still would have waited.
Until you have mapped out all the coax, wiring and tubing runs it makes sense to wait. You will have relatively easy access to the centre section. The fewer holes in that area the better.

[KayS]

If Vans states that one can put holes in an area then it shouldn't be a proplem for the structure. I really regreted that i didn't drilled them in first place. It's amazing how much stuff you have to route to the back. I was thankful for every hole that i needed for wires etc. And the holes you don't need weigh nothing.

It's very hard to estimate how much you need later. So my suggestion is to put them in now.

[Raymo]

Highly recommend drilling the extra holes in the center of the spar. Once the flight controls are in, it is not possible, unless pulling them back out again.

The plans show exactly where you are permitted to drill the holes.

[Desert Rat]

Just to clarify, I definitely see the potential need for extra holes, and I have the doc from Vans website that shows where it's acceptable to put them. But that document allows them to wander around quite a bit based on hole size.

My question was more along the lines of; do you guys who've already done this recommend that I go ahead and put the max size hole somewhere in the relatively big zone thats allowed because its easier now, or wait until later in the process to more precisely locate...

[KayS]

Could you provide a picture?

[Desert Rat]

I can do better than that

Here's the Vans document. You can see that there's a ton of variation on where you can put extra holes depending on size.

https://www.vansaircraft.com/faq-tec...ion-bulkheads/

[PilotjohnS]

I am building a 9a, a sister to the 7, (same body, nicer legs). I have finished all my wire routing to the back and dont think I will need extra holes in the spar for wiring. The savior was the LED landings lights from FLYled. The wire size that they required is much smaller than traditional lights. So I dont plane to drill and additional holes.

[Ralph Inkster]

Awkward later, yes, but I'd wait till you can trial fit the stick control system so you can find good hole locations that will not interfere with control movement.

[KayS]

I would place one hole 3/4" (standard snap bushing) on the lower part of each outboard section. That should be enough in addition to the holes that are already there. If you wish to reduce the hole diameter you can insert/glue a smaller snap bushing into the 3/4" bushing.

The inboard holes are probably not needed and could interfere with the controls.