Saturday, March 2, 2019

Section 15 - Rear Spar (aileron hinge bracket assemblies; spar doublers)

Started the Rear Spar (left side only) by spending an inordinate amount of time prepping the aileron brackets, and trying to figure out which parts of the service bulletin (SB) pertain to folks like me, who are starting the build process (and don't already have a flying airplane that needs the fix).

Parts for both the inboard (shown on the left; i.e., the SB) and outboard (right) were cut/trimmed as necessary, match-drilled, deburred, and primed:


Match-drilled the smaller, outboard rear spar doubler:


Match-drilled the larger, inboard and outboard rear spar doublers; traced the left aileron pushrod hole onto the doubler; fabricated the hole:


Left aileron pushrod hole shown in the middle (all 3 doublers will eventually be primed):


Riveted outboard aileron bracket assembly, below.  After riveting the aft-most three rivets, the bearing got far too tight for my liking, so I removed all the AN426 flush rivets, which loosened the bearing.  I then re-riveted the AN426 rivets one-by-one until I figured out what was happening - it seems the bearing needs a little more "play" in the recesses, since even a little pressure from a squeezed rivet was enough to bind the bearing.  I'll also note that the bearing seemed to fit too tight when I pushed it into the recess of the center W-1013A bracket.  I'll order those parts next week, and try again, this time paying far more attention to how the bearing is situated in the recesses. Since the parts will only be around $60 shipped, and I feel this bracket and bearing are critical for smooth flight (and a happy trim tab motor and autopilot servo), I'd rather start with a clean slate.


Riveted inboard aileron bracket assembly (i.e., part of SB) - this bearing moves freely; the SB has a much better design for inboard aileron bracket (2 pieces, instead of 3, and a very slight amount of play in the recesses where the bearing fits).  I wish Van's would have incorporated this new design into the outboard bracket!


Clecoed the rear spar, doublers, fork, inboard doubler plate, and inboard aileron bracket assembly; match-drilled holes:


Another view:



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