March 29, 2011 – I started installing the right leading edge to the main spar. The plans call for solid rivets for the rib/spar install, but access to shoot them is something of a challenge, so many people use pop rivets. I really didn’t want to do that, so I decided to use hi-locks, a fastener that theoretically only requires access to one side. Hi-locks are fasteners made of either steel or titanium that are secured with a collar that has wrenching flats that break off at the correct torque. I wanted to install them from the forward side of the spar so that I could install the collars on the aft side where I had room to work. They would also be easier to remove should the highly unlikely need arise. As it turns out, there wasn’t enough room to get a wrench or socket on the collars from the aft side, because they were up against the main ribs. So I drove the fasteners in from the aft side and installed the collars on the forward side. I used -5 fasteners, so I had to enlarge the holes in the spar and the ribs to #21. That drill size also allows for an interference fit of the hi-lock.
Did I gain anything from using these over pop rivets or solids? Probably not. I ended up having to modify my pop riveter for the tank z-angles anyway.
I still have to install the rivets for the leading edge skin and the main spar.