Drilling for conduit... confused!

[danielhv]

I am ready to drill the wing ribs for "conduit or gromets" as the directions say... question is, I dont know what to drill! I do not know which pitot Im using, or what nav/stobe/landing lights im using, etc. Is it all one size fits all? Is conduit better than gromets? Im considering the pitot-static kit from safeair1, but have not committed yet. Should I just wait on drilling these holes until after I cleco everything, match drill, and disassemble to deburr?

[fehdxl]

I was able to drill holes for the conduit after they were riveted to the spar and the top skin was riveted. The trick was to use some 12" extension with the unibit to get at the inboard ribs that were too closely spaced for the drill to fit.
So I guess the bottom line is, build on, you can do it later if need be.

-Jim
RV-10, flaps

[jferraro17]

Dan-

Check this out:

http://www.rv7factory.com/log/051121.html


This and subsequent pages gives you the conduit, grommets, AOA/AS/ALT runs & locations, etc. I found it to be a very flexible setup for future decisions. If you go SafeAir, this will work out for you. Much easier to do now, then once the wing is assembled.

Joe

[Rick6a]

Originally Posted by danielhv

I am ready to drill the wing ribs for "conduit or gromets" as the directions say... question is, I dont know what to drill! I do not know which pitot Im using, or what nav/stobe/landing lights im using, etc. Is it all one size fits all? Is conduit better than gromets? Im considering the pitot-static kit from safeair1, but have not committed yet. Should I just wait on drilling these holes until after I cleco everything, match drill, and disassemble to deburr?

Grommets are fine up to a point but for maximum utility I suggest you install a run of Van's lightweight conduit in each wing. It does not matter one whit the pitot, landing light, nav light, antenna, etc. you may decide to install later. The plans would have you drill an additional hole in each rib to route the flexible conduit through. That is perfectly fine. I happened to choose an alternate way of installing the conduit just because I could but the important thing is once conduit is in place inside the wing, you can thread all the wire or coax through it that you may ever want now and in the future.
http://www.vansairforce.com/communit...onduit+bracket

[n2prise]

Daniel,

You should plan it out NOW, before you rivet it all together. This photo shows how I put in plastic tubing conduits from Lowes during the wing construction. This photo appears on page 13 of my web site. http://www.n2prise.org/rv9a013.htm I drilled all the holes and opened them up with a unibit before I riveted the upper wing skins to the ribs and spars. See my page 15 to see them both installed. http://www.n2prise.org/rv9a015.htm



If you are planning on an angle of attack pitot tube, put in two sets of plastic grommets in each rib near the center one you see in the plans and my photo above.

[Robert M]

Here is a picture of me marking the holes for the electrical conduit.



Link to larger image....

http://i270.photobucket.com/albums/j...leposition.jpg

Here is a picture of the electrical conduit and snap bushings for the "air" lines.



Link to larger image....

http://i270.photobucket.com/albums/j...pitotlines.jpg

I used the Van's conduit and the bushings I got from AS.

[LarryT]

Perhaps someone will find this useful. Because hole saw mandrels are bigger than 5/8 or 3/4 dia hole I had to come up with another solution to drill the conduit holes in already assembled wings. This was my solution:
1. Purchase a long 3/8 dia steel rod.
2. Turn down and thread one end for a roto-broach (available from Avery Tool). Make the threaded end long enough that you can thread two nuts on to become the shoulder to tighten the roto-broach against.
3. Center drill the same end to hold a pilot drill.

It took me a little while to come up with this solution and a couple hours to modify the end of the rod. It took no time at all to drill the holes through the ribs. I did not feel that I would have any success with an angle drill trying to go in through access holes. The long rod enabled me to drill rib-by-rib from outside the wing and get most of the ribs. The remaining ribs were drilled because there was still some access through the unskinned lower outboard section.

The roto-broach bits are similar in cost to two bi-metal hole saws plus a hole saw mandrel.

It would be better if Van's put these holes in the flat pattern before forming, especially since they have issued an SB both permitting and locating the holes. It's an example where the QB kit could be made more "user-friendly." Just like having a set of QB instructions so one didn't have to figure out what was done, what wasn't done, and how the partial completion affected the build sequence. It could potentially save Van's money for technical support it they had someone appointed as an "ombudsman" to follow up on erata pointed out by customers, suggestions for improvement, and quality assurance/design intent issues with some of their peripheral item vendors.

Larry

[RV10Rob]

What's the downside to just running the conduit through the lightening holes and securing it with safety wire or zip ties? All you need to do is drill a tiny hole next to each lightning hole, as Van's describes in their doc. Seems like a much easier solution, especially for QB wings.

-Rob

Originally Posted by danielhv

I am ready to drill the wing ribs for "conduit or gromets" as the directions say... question is, I dont know what to drill! I do not know which pitot Im using, or what nav/stobe/landing lights im using, etc. Is it all one size fits all? Is conduit better than gromets? Im considering the pitot-static kit from safeair1, but have not committed yet. Should I just wait on drilling these holes until after I cleco everything, match drill, and disassemble to deburr?

I didn't use conduit, but I did drill some new holes for gromets so I could run more wires through it that the original hole diameter would allow. Feeding wires through the wing after the fact without conduit is a non-event. You can reach every one of the ribs inside the wing either from the tip end or through the inspection holes. I recently added a remote compass on the wingtip. I had no problem running the wires out to it. IHMO, people make a bigger deal than is necessary about being able to run wires after the fact. Here is a pic of where I put my holes:



That said, if I had to do it again I would use a 10-foot section of PVC pipe (or equivalent conduit) in the second ligntening hole aft of the spar. Secure it to several ribs, and you're done. You don't have to drill anything except a few small holes to secure the conduit to the ribs. The area in the first lightening hole aft of the spar is too cluttered up with stuff (aileron pushrod, etc). Additionally, the second hole aft of the spar lines up perfectly with where you want the wires to enter the fuselage (at least on an RV-8). You most definitely need to think about where you want the wires to enter the fuselage before you decide where to put them in the wing. I didn't, and conesquently my wires are running right along the spar. When they get to the root rib, I have to run them aft along the root rib to enter the fuselage abeam the second ligntening hole. If it had just run them through a piece of PVC installed in the second lightening holes, it would have been a straight line and much simpler.

[mike109g6]

Originally Posted by RV10Rob

What's the downside to just running the conduit through the lightening holes and securing it with safety wire or zip ties? All you need to do is drill a tiny hole next to each lightning hole, as Van's describes in their doc. Seems like a much easier solution, especially for QB wings.

-Rob

Personally I'd keep the aileron tube holes clear of anything except the tube. Drilling holes for either grommets or conduit is not that big of a deal, put the hole anywhere you want, down and toward spar is best. With conduit the ribs will keep it localized and absolutely no possibility of the conduit breaking free and wrapping itself around the aileron push tube-that would be a bad thing. Also the conduit makes it much easier to wire AFTER the wing is closed, or to add or subtract wiring later if you change your mind.
Mike H 9A/8A