I first located and back-drilled four 3/16" holes into the root doubler. This allowed me to temporarily attach it so it would be extremely stable. Next I used drift pins to locate the center of each hole. The time consuming part of the process is step-drilling all of those holes on the drill press up to one size short of final. After replacing the part on the wing, I then hand reamed each hole to final size. Everything fits just like it is supposed to.