Vertical Stabilizer Rear Spar Rivnuts

[Montreal]

Can anyone shed light on why the rivnuts at the bottom of the vertical stab rear spar are sandwiched between doublers? Why wouldn't they be installed through spar and 2 doublers?

[lutorm]

There's been a fair amount of discussion of this either here or in the sling builders facebook group. The conclusion, as I recall, was that the intent is that by sandwiching them between the parts any pullout force is transferred through the rivnut face onto the spar. If the hole went through everything, all pullout force would have to be taken up by the deformed part of the rivnut itself.

[Montreal]

I asked Sling technical about the spar rivnuts and they said "this gap will be eliminated when the screws are fastened in the subsequent assembly step." Not exactly the answer I was hoping for but time to move on. Thanks for the feedback @lutorm