Aileron bellcrank pivot assembly

[dbdevkc]

In assembling the left aileron bellcrank pivot assembly, I noticed a couple of things:

- The head of the bolt that goes through both angles and the phenolic and clamps the whole assembly together does not sit perfectly flat against the flat part of the angle piece. This is because of the inside 'curve' of the angle piece. Should I be concerned? Has anyone else noticed this?

- Also it seems to me that the bolt called for there (AN3-6) is too short. An AN3-7 with a washer would work better.

- There is a note to tighten the nut to lock the bushings against the bellcrank (otherwise the bushings rub against the bellcrank plate and start cutting a gouge almost immediately) - but that would be the castellated nut. So why not just have an elastic stop nut there?

[dbdevkc]

- The head of the bolt that goes through both angles and the phenolic and clamps the whole assembly together does not sit perfectly flat against the flat part of the angle piece.

I am going to get in there with the half round file to get just enough of the inside curve flat so that the bolt/washer sits flat, then use a rat tail file and scotch brite to smooth and clean it all up.

- There is a note to tighten the nut to lock the bushings against the bellcrank (otherwise the bushings rub against the bellcrank plate and start cutting a gouge almost immediately) - but that would be the castellated nut. So why not just have an elastic stop nut there?

So after thinking about it if it were an elastic stop nut, the turning force could loosen it up just enough to allow the bushings (the "inside" bushings that go on the bolt and inside the flanged bushings) to turn on the bellcrank itself and scratch it up. I'll be using the castellated nut and pin and (per the plan revision note) make it tight enough "to lock bushings against bellcrank." The cotter pin will lock it in place.

[Bryan Cotton]

Kevin,
I went back and looked at my pictures. I don't remember a problem with the radius, but it may have been there. I have used shims many times when too tight on a radius. Regarding self-locking nuts vs cotter pins, control system bolts that could be subject to rotation must use cotter pins per AC43.13 I believe. It is a good practice.

[dbdevkc]

Regarding self-locking nuts vs cotter pins, control system bolts that could be subject to rotation must use cotter pins per AC43.13 I believe. It is a good practice.

Yeah, thanks. I'll be using the castellated/pin. In theory though... the bolt would not rotate in relation to the internal bushings - so no turning force on the nut itself. Unless the bushing bind, then all bets are off.