Title: 23-05 - Bellcrank Preparation and Installation
7/24/23 - 1.8h 7/25/23 - 0.7h 7/26/23 - 0.2h I am jumping around a bit in the plans during this section depending on the tools and parts I have available as well as the work session time. This step is out of order since I need to get to a drill press to prepare the various pushrods. Installing the aileron bellcranks is very satisfying, since you finally get to see some moving parts attached in their final position. The bellcranks need a little preparation before installation into the wings starting with riveting a nutplate for a future autopilot servo onto the right wing bellcrank. The holes for the nutplate have to be final drilled and countersunk, and then the nutplate is riveted in place. The bellcrank has two sets of nutplate holes, and the drawing in the plan says both sets are to be countersunk even though only one nutplate is installed. I countersunk both sets, primed the countersunk holes to prevent corrosion, and then attached the single nutplate to the bottom arm of the bellcrank. Each bellcrank rotates around a pivot tube, and the pivot tubes receive brass (I think…) bushings. The length specification for the bushings is between 69.9mm and 70.6mm, and both of my bushings were delivered around 71mm long. A couple light passes with a flat file, fine sanding, and final cleanup with a Scotch Brite pad did a nice job of reducing the length to the specified length. I twisted a 1/4" reamer by hand in each bushing to allow an AN-4 bolt to slip in without binding, and then deburred both the pivot tube and bushing to allow the bushing to easily slide into the pivot tube. The pivot tube must be 0.8mm - 1.6mm shorter than the bushing, and both of my bellcranks met that spec without any additional modification required. The final step is installing the bellcranks into the wing brackets, and securing the bellcranks with the specified AN-4 hardware. The installation is straight-forward as long as you pay attention to the bellcrank orientation in the plans. Once the bellcranks were in position, I torqued the nuts to the value in Plans Section 5 (85 in-lbs + drag) to complete the installation [#40 Drill, #21 Drill, 1/4” Reamer, #40 Microstop Countersink Cage, Rivet Squeezer, Flat Squeezer Set, Flat File, Hole and Edge Deburring Tools, Torque Wrench, Rust-Oleum Automotive Self Etching Primer (Green – Rattle Can)]


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