Thursday, May 17, 2012

Trim Tab Hinge Pin Solution

I was reading ahead in the plans and found that they secure the trim tab hinge pin to the spar using safety wire. This is probably ok, but I feel it would need a close inspection before every flight to ensure that the safety wire isn't corroding away or wearing through. I've seen safety wire wear through on a Cessna 172 door and would hate for this to meet the same demise. I wanted to come up with something a little more permanent. So I went to the Van's Airforce website which is a forum for RV builders to discuss....well almost everything airplane. With a quick search I came across a solution that I like...reposted below.
This will be my plan, simple.
"I struggled with finding a way to secure the hinge pin on the elevator trim tab until I saw this technique used on some RVs that I looked at up at Air Venture.

As supplied in the kit, the hinge is longer than what's needed. When you trim the hinge to length, be sure to NOT cut the hinge pin. Leave it long and extending past the end of the elevator as shown above. Now bend the hinge pin so that it will lay across the web of the spar.

Take a spare piece of hinge and cut out one eye. Drill a hole in it for a #6 screw. Slip it over the hinge pin and locate the position of the screw hole in the web of the spar. Remove everything and attach a #6 nut plate behind the hole. The nut plate will fit on the forward side of the elevator trim spar web where it extends past the edge of the inside elevator rib. When you're done, you'll find that you will be able to get a long bladed screwdriver on the screw even with the trim tab mounted and in-place.  "

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