Manual trim cable route

Can anyone installing a manual trim cble confirm that the 5/8" routing hole on bulkhead 706 goes through the 729A bellcrank rib flange (and the optional electrical wiring 5/8 hole on the opposite side of the center line also goes through the bellcrank channel flange) as well as through the F-730 reinforcing plate?

The only mention is DWG 21 that indicates it should go through the baggage rib on the one side. But it would be pointless, I suppose, to drill through the bulkhead AND the baggage rib and not the reinforcing plate and -- similarly -- it doesn't make sense to have an optional run on the ther side in the same location without going through the channel.

One begats the other, as near as I can tell.

Bob,

You are correct. Drill them as set prior to riveting the center section as it is very difficult to drill once things are all together. (If you can that is.)

You do want the "optional" hole as well. I also added two addition runs. You can see pictures here:

http://www.n523rv.com/fuselage/2004/08/steps-and-baggage-floors.html

Thanks, Matthew, for the confirmation.

Stupidly, I initially drilled the 5/8" hole using DETAIL A and the reference to the baggage rib. Unfortunately, there was no description of the baggage rib anywhere on that DWG and -- equally stupidly -- I attached the baggage rib going aft and it wasn't until I started fitting stuff together today that I realized the baggage rib goes forward. So the hole placement on the rib is now reversed. Solution: Order two new ribs ($22).

I wouldn't have minded on a drawing that references the aft bulkhead structure, if Detail A had included a reference to the hole in relation to the bellcrank rib and channel. If it had, I would've put the pieces together aft and figured out that something's not right there. (OR I would've liked to have seen that the channel and bellcrank rib were eliminated for clarity)

You keep having to pop back and forth between DWG 21 and DWG 26 and it's actually DWG 25 that reveals what goes where.

Just one of those days when I'm too stupid to be building an airplane.

Manual Trim Overall Route

Bob,

The fun is just beginning with the manual trim cable. I'd install one again rather than electric, so don't take my cautions wrong. I am writing from recollections aged up to four years, so hope they're accurate, since you won't encounter these difficulties until you're hot to assemble the airplane and go flying.

The hole drilled in the main spar web of the stabilizer is large enough to pass the largest diameter of the aft end of the cable and not cut into the web reinforcements (you riveted on as practically the first assembly operation of the kit). Therefore, at installation, you cannot insert a large enough bushing to pass the entire cable without opening up the hole and removing material from the reinforcements to accommodate the bushing. (Also, the overall thickness of the spar is too great for a snap-in bushing to lock in place.) I did not open the hole, but I'm not worried about chaffing as it's not a knife edge sheet metal hole, and the cable is metal sheathed. How you route the cable plays a role in whether or not the sheath bears against anything. I found the most direct route with the largest radii to be through the bulkhead lightening hole above the horizontal's saddle, not up through the saddle. Also, an adele clamp here and there will help stabilize the installation.

From the baggage bulkhead aft you must suspend the cable in some manner so that it can't touch the fuse bottom skin or it will wear through the skin eventually. Plan which way to face the bulkhead plastic bushings so that you can (adele) clamp the cable against the bushings in the direction they are inserted. I also added several clamps to ribs forming the center section elevator pushrod tunnel to further secure the cable against shifting fore and aft and drooping.

There is a "sweet" radius for the cable that bests accommodates the angle of the knob/fuel selector mounting plate with the floor (actually, the cover over the floor center). Find that first, eliminate slack aft to the baggage bulkhead and forward from the stabilizer blukhead, then deal with any slack in the run between the baggage and horizontal stab bulkheads where you have some sway space in the fuse cone.

Further, plan now your wiring/coax/static & fuel tube routes. Drill all the holes you think you will need in ribs, bulkheads, and wing spar center section web, and then some, allowing for bushing O.D, and how you will access those holes to install/remove bushings and their occupants, and not interfere with control movement. Van's instructions are really weak on systems installation and the numerous holes needed, understandable since every airplane's different.

John Siebold
89 hours on a 7

Hey, John, thanks for the note. I was suffering from only a minor amount of information overload and thinking the project is ahead of my ability to think and now I'm overflowing with it! (vbg).

Seriously, good advice. I paid particular attention to your note to plan the static, wiring routes now. Now, keep in mind, I'm a guy who couldn't figure out that a simple rib went forward and not aft! (sigh). I don't know, yet, what's in the panel or what's supposed to go where or even the nuts and bolts of the static kit and where it comes from, where it'll go etc. I've tried to read the Aeroelectric book several times and much of it is still over my head.

So I'm sort of a "if I don't bother it, it won't bother me" stage with the systems, even though I now realize that that's a stupid approach to take.

BC

Route Planning

Bob,

Don't beat yourself up - too much; there are days when chickens are more organized and logical than imperfect humans. You're working on the center section; consider all the empennage kits put up for sale. Your bird is going to fly.

I logged 1800 construction hours. I spent at least an additional 400 simply thinking about what ifs and planning. And those floor ribs? More than once I clecoed the wrong end to a bulkhead, or mixed up left and right during fit-up. You aren't alone.

You might want to install nutplates to receive screws rather than pop rivet down the baggage floors. Then retrofitting passages for aft-destined systems isn't very difficult. Alternately, and a lot less effort, drill holes for the largest snap bushings on each side of the center section bulkheads, a bit above the bottom skin, a pair per side. This will allow system interconnections from the spar to the tail cone to run between the fuse side and the first center section rib inboard. These are some of the possible uses: static tube, from 1 to 3 strobe cables and strobe power (depends where you mount the power supply, tail light, an antenna coax perhaps, ELT data cable. The middle tunnel for the elevator pushrod will also house the trim cable and some of the systems interconnects. You won't fill all the bushings, but you will have lots of options.

John Siebold

//Don't beat yourself up - too much; there are days when chickens are more organized and logical than imperfect humans. You're working on the center section; consider all the empennage kits put up for sale. Your bird is going to fly.

You know, that's right, it is. What a weird feeling. I find myself starting to worry about how I'm going to afford an engine, insurance, and a hangar...all ...you know.. .FLYING stuff. It's kinda cool.

//You might want to install nutplates to receive screws rather than pop rivet down the baggage floors. Then retrofitting passages for aft-destined systems isn't very difficult.

There was a good article in RVATOR a few years ago with Van's employees writing what they'd do differently with their birds and this was the one thing that jumped out at me as a terrific idea. Thanks for reminding me.

And thanks for the tips!

B