Tweaking The Fit Of The Eagle’s Wings

The instillation of the spar pins used to keep the wings secured has been a bit of a struggle both timed the wings have been mated to the fuselage. The first time when marking for the required 1/8” clearance between the wing skins and the fuselage, it was noticed the lower wing skins were touching the doublers that were installed on the sides of the fuselage … at the time it was thought this was probably the cause of the tight spar pins. Nope.


After removing excess material prior to mating the wings for the second time it was discovered the spar pins still were way too tight. Analysis of the situation with a mirror showed the right wing needed to go in just a little further so the bushings could align perfectly. Looking at the retainer block showed there was no clearance and it appeared the retainer block was preventing the spar from going in just a tad further. Thinking perhaps the rubber seals were causing an issue they removed but the spar pins were still way too tight.  The decision was made to remove the wings and sand 1/32" of material from the bottom of the block in the hopes it would allow the wings to be inserted just a tad bit further.

One of the two white F-1204R retainer blocks attached to each side of the center section. It appeared as though this retainer block was preventing the right wing from going inward just a tad further, so it will be removed for trimming along with the one on the right side. At this point the spar is tapered so removing just a tiny bit of material will allow the spar to be inserted just a tad further.

A line was marked on all four sides of both F-1204R retainer blocks so a 1/32" of material could be evenly removed from each of them.


The F-1204R retainer blocks were placed on a piece of sandpaper and sanded down while rotating the block often to make sure it was being sanded evenly. Material was slowly sanded away until the 1/32" red line was gone. The retainer blocks were reattached onto the center channel and the wings slid into the center channel. Ultimately, sanding a 1/32" off the F-1204Rretainer blocks solved the problem. The left wing was installed and both spar pins were inserted to hold the wing in position but not pass through the bushings. Next the right wing was slid into position and an instant difference was noticed, in that, one could feel the alignment was much better and after a little pushing and rotating of the spar pins they slid into the bushings of on the right spar. At this point it would have taken a soft faced mallet to seat the pins the rest of the way, now I was able to tap on the spar pins with the palm of my hand to fully seat them. Finally, a good fit!!!


Gee, before taking the wings off again to do a little more clearance filing on the right flaperon and to reinstall the gap seals, why don’t we roll the Eagle out of the hangar and start the engine? Sounds like all the makings for a big announcement in the next post.