drill holes #30 on Main Spar

[Fedico94]

Is it permissable to drill four holes in the aft face of the front spar (3rd bay in from wing tip) to mount heat controller box for a heated pitot tube ?
Pictures I see on the web show such devices mounted on the rib rather than the spar

 

[cytoxin]

close to the root

i would call vans on that one.

 

[Kevin Horton]

The vast majority of the spar's bending strength is provided by the spar bars (inboard part of the wing) and the flanges on the top and bottom of the spar. The purpose of the spar web, waffle plate and spar bars is to ensure that the top and bottom of the spar remain the correct distance apart. The bending strength would be reduced if the distance between the top and bottom of the spar were reduced.

#30 holes on the spar web will have a negligible effect on its ability to do its job. There will be no reduction in spar strength or fatigue life, assuming normal hole spacing, deburred holes, etc.

Build on.