Tom Martin
Well Known Member
I am making a minor modification to the aileron bellcrank installation that I present for your consideration and dialogue.
The bellcrank is installed on a 3/8" O.D. brass bushing that is captured between and upper and lower bracket on the spar.
When the bolt is tightened properly the bellcrank is supposed to rotate freely on the brass bushing with a very slight up and down movement along the bushing.
My concern is that the metal bellcrank, although it rotates on the bushing, rests on the bottom aluminum bracket. Each time it turns there will be contact between the end of the metal 4130 tube and the face of the aluminium bracket.
The addition of a 960-616L washer will eliminate this contact. The washer goes over the bushing and is free to rotate around the bushing, this can be seen in the picture below
This is one of those long term issues. I can see no problems with this addition and it has the potential to reduce or eliminate wear at this important location.
I was able to install this washer without any trimming of the bell crank or the supplied brass bushing, while maintaining the torque and "play" specified in the plans.
(maybe the engineers left the correct spacing for this washer and it somehow got omitted in the plans?)
The bellcrank is installed on a 3/8" O.D. brass bushing that is captured between and upper and lower bracket on the spar.
When the bolt is tightened properly the bellcrank is supposed to rotate freely on the brass bushing with a very slight up and down movement along the bushing.
My concern is that the metal bellcrank, although it rotates on the bushing, rests on the bottom aluminum bracket. Each time it turns there will be contact between the end of the metal 4130 tube and the face of the aluminium bracket.
The addition of a 960-616L washer will eliminate this contact. The washer goes over the bushing and is free to rotate around the bushing, this can be seen in the picture below
This is one of those long term issues. I can see no problems with this addition and it has the potential to reduce or eliminate wear at this important location.
I was able to install this washer without any trimming of the bell crank or the supplied brass bushing, while maintaining the torque and "play" specified in the plans.
(maybe the engineers left the correct spacing for this washer and it somehow got omitted in the plans?)
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