<February 23, 2007>
Miscellaneous Flap Work
I still had a few small loose ends to tie up with the flaps, so that is exactly what I did tonight. All of the work tonight involved the FL-706Bs and As. First I enlarged the hole in the rib and FL-706Bs for the nutplate that will fasten the flap actuator rod end bearing to the flap (wow, that's a mouthful), then I took a few minutes and improve the fit of the FL-706Bs to As.
I used a 1/4" bit in the drill press to enlarge the aft hole in the FL-706Bs and ribs. I clamped the pieces down (to the drill press) really well, with a scrap block of wood underneath. Using high speed and low pressure, I enlarged the holes. If the pieces aren't clamped down and no backer material is used drill bits have a tendency to make triangular holes. Not not this time, I did it right and the holes are perfectly round. One the 1/4" holes were in place, I flipped the part over and used a AN4 bolt to hold the nutplate in place while I drilled the rivet holes. The I flipped the part over again and countersunk the rib and FL-706Bs to accept the nutplate rivets. Yes, I know the rib is too thin for real countersinking, but for the aft rivet (the one that goes through the rib only) I used by deburring bit to countersink only slightly for a NAS1097 rivet.
Once all the drilling and countersinking was done, I clecoed the FL-706Bs to the FL-706As and used the sander and deburring wheels to make the profiles of the front flanges of each part match perfectly. This wasn't necessary, but I did it anyway.