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F-1005A Rear Spar Bulkhead

Blizzard

Active Member
Is it acceptable/safe to drill through the F-1005A to pass conduit through? There's already holes and snap bushing through it for control pushrods, rudder cables, and battery cable openings. Seems to be the most direct route from tail cone to side wall access for wiring and etc.. Would preclude drilling multiple holes through the rear seat ribs to get to the side walls for the path forward. Thanks for any input pros and cons.
 
This is a difficult and controversial question to answer. Van's does not give much guidance and did not leave much in the way of natural routing even for the battery, elevator trim, and tail light. Anything more and you are forced to make additional penetrations - at your own risk. Since we know that many RV-10s are flying with additional equipment in the tail cone (pitch and yaw servos, remote ELT, antennae, air conditioning, etc.) then it appears that a certain amount of extra penetration is not immediately harmful. Just don't get carried away.

The problem with penetrating the F-1005A is that you must immediately make a 90 degree turn to stay under the flap actuator covers. Generally, you prefer conduit as straight as possible to avoid problems feeding wire into it. I ran my AHRS cable through the left side because my AHRS lives under the passenger seat, so I only needed conduit through the sidewall. On the right side, my conduits (and A/C hoses) continue through the sidewall to penetrations I made in the baggage bulkhead.

On the left side I had to drop my conduit through the baggage floor before reaching the baggage door, leaving an undesirable vertical S-turn in the conduit. A better option might have been to penetrate the seat floor instead, as well as the first F-1017A, before passing through the precut hole in the next bulkhead, allowing a gentler, but still not straight, transition. Sometimes there is no perfect answer.

When the lift my project was on failed, the fuselage skins were wrinkled behind the main spar - it was that hard a drop. But removal of the skins and examination of the structure underneath showed that the areas where I had made additional penetrations had stood up just fine. That's not proof, just anecdotal evidence, but I will feel better once I've got the new skins back on and eventually finally complete the aircraft.
 
I ran my cables/conduit above the floor back to the cavity that is covered by the passenger side panel / armrests, then drilled through the floor under that cover to get back behind the baggage wall. Conduit terminates just above the floor. Very easy to pull/push wires through a conduit that terminates in this area, even with the multiple bends.

Larry
 
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Thanks for the input. All very valid points and recommendations. I understand fully the hesitancy to comment on subjects like this. One of my plans was to put a couple of 3/4 inch "tooling" holes in the 1005A bulkhead and terminate right there. Run un-conduited wire from there the rest of the way through the sidewalls through nylon grommets. Second option was to pass through a seat rib and then up and to the side walls through that route. My problem is how to make the holes in the ribs??? No room to put a 90 angle chuck with a unibit on it. Maybe someone could relate what "a friend of mine did" and how they dealt with it. As far into the build as I am I really didn't expect to be scratching my head this much over !$#@% conduit!! LOL Thanks again.
 
I planned my conduit runs before putting on the side skins but the thing that kept me from using the route through rib was just what you mention plus I'd have to do it three times (A/C hoses consume conduit routes on the right side). I would have had to procure a flex shaft for either drill or dremel and use a grinding point to hand carve the conduit holes, oblong so the conduit could pass at a shallow angle. Another option, more expensive, is an angle die grinder (Sioux has one for about $160). Later, when I had to deal with passing the conduit through the baggage floor next to the skin, I wished I had gone with the other routing but I made it work.
 

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