Too Many wires and Tubes

[pvalovich]

-8A N192NM, forward mounted battery, AFS-3500, AOA, ADI II Pilot, Strobe power pack mounted in aft bagage compartment, electric trim and indicators, Infinity Stick Grip, electric flaps, pitot and static lines under the floor, flodd lights - all of which require wires/tubes through the spar assembly. I drilled holes through the web(s) IAW Van's wiring directions, but have run out of space for additional wires through existing holes.

Can I drill another 3/4 hole through the web(s) without compromising strength? I understand the flanges take the load, but intuitively, it seems there has to be a swiss cheese limit.

[Kevin Horton]

The wing bending loads are carried by the large bars at the top and bottom of the F-804 bulkhead. The vertical bars at the outboard ends of the 804 serve to keep the top and bottom horizontal bars from moving closer together, which would greatly reduce the bending strength. In short, the aluminum centre section web carries essentially none of the wing bending loads.

Another few holes won't have any practical effect on the strength of this part of the structure.

[Jeff Vaughan]

I emailed the folks at Vans about this. They were OK as long as you followed their measurements that they gave me. I have been surching for the email and can not locate it. As I remember the hole can not be any closer to the edge , Top or bottom, than the others.

Sorry I am not more helpful. I would ask Vans