December 15, 2019

Torque Tubes Part 4

Hopefully this is the last significant update on the torque tubes for a while. A made a few small adjustments to the floor ribs and that seems to have improved the friction issue. There’s still some resistance, but I think that’s unavoidable since there are 4 bushings. I recorded a short video to demonstrate what I was able to achieve:

Next I worked on building up the center console, which is the next step in the build manual.. however it seems like I should wait to finish closing out the console until after I’ve run wires and the the rudder cables. A quick review of Craig’s fuselage build order confirms this, as well as a review of the factory build fuselage pictures on Craig’s blog. I feel like I’ve put in a lot of rivnuts, more than the build manual calls for. But to me it makes sense to be able to remove these panels for inspections and maintenance. The Z-sections and other brackets I recently installed already had a bunch of rivnuts, which led me to believe that these skins were intended to be removable, so I just continued and put in more rivnuts rather than rivets. I have enough rivnuts, since I order a bunch from Amazon a while ago, but I had to order more M4x12mm button-head screws to secure the panels, since the center fuselage hardware parts bag only included qty 15.

Rivnuts installed to CF-PLT-015-X-C-
Test fitting the skins and the little compartment underneath the armrest
Not sure why this skin has a big round corner, since it goes beneath the cap of the main spar carry-thru, which has a sharp corner. I had to file the corner to make it fit correctly

Next I installed the flap motor, since everything was in place and it was easily accessible

Here’s a short video demonstrating extending and retract:

One thing I’m unsure about is the proper torque to use on the nuts that secure the flap motor. The kit supplies AN5 bolts and AN310 castle nuts. Per standard practice (AC 43.13-1B) these nuts should be tightened to 60-85 in-lbs for a bolt under shear stress; but tightening it this much makes it difficult for the extension arm of the flap motor to rotate the torque tube. For now I decided to just tighten the nuts to finger-tight, and then put in the cotter pins to prevent the nuts from backing out. I’ll do some more research and/or contact TAF about this, but I’m going to move on for now.