In message <19980108.075609.31471.0.ErichDTrombley@juno.com>, Erich D
Trombley <erichdtrombley@juno.com> writes
>Just how did you rework the clearances? I too have stiff roll control
>which is directly related to temperature. I am getting ready to bond the
>cockpit module to the fuselage and would be interested in a fix.
>
It is important to establish the cause of the stiffness and cure it at
this stage. I set up my front bearings with a 0.01 inch shim so I
expected them to be quite free. I also remanufactured these bearings
incorporating a grease nipple. I was therefore disappointed when I
finally bolted up the controls that the aileron circuit was stiff at
times and temperature dependent. I finally traced the problem to a lack
of perpendicularity of the bearing to the aluminium shaft. Although I
had tried my best with the flox base for the bearing, it clearly wasn't
quite true and when I came to tighten up finally the extra load pulled
them off the perpendicular. A possible problem is the shaping at the
shorter edge of this Tufnol bearing which may be too firmly in contact
with the module. (i.e. it may not have been shaped sufficiently). I had
made my bearings removable rather than having bonded them in with the
flox and so I was able to slacken off the bolts and demonstrate that
they were once again free. The solution was then to shim out the front
bearings from the flox bed. For this I used pieces of epoxy printed
circuit board, suitably wedge shaped where necessary (in cross-section)
and with holes through to take the bearing retaining bolts. This was
tedious and difficult because it involved retightening the bolts for
each test. As I think it was Tony Krzyzewski who wrote, a good test is
how easily the control columns will return to the vertical under their
own weight when deflected and released.
Ken Whiteley
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