Andrew=0AYou are right about the problems of thermal expansion etc. I had a
problem due =0Ato the clearances being too close. Going from a warm hangar
to cold air (flying) =0Athe roll control stiffened up, due to the aluminum
contracting quickly and the =0Arest of the airframe slowly. After an hou
r the controls had loosened up again.=0AGraham=0A=0A=0A=0A=0A=0A___________
_____________________=0AFrom: Andrew Sarangan <asarangan@gmail.com>=0ATo: E
uropa List <europa-list@matronics.com>=0ASent: Sunday, 28 August, 2011 17:0
7:32=0ASubject: Europa-List: Tufnol bearings clearances=0A=0A--> Europa-Lis
t message posted by: Andrew Sarangan <asarangan@gmail.com>=0A=0ALooking thr
ough the email archives, the alignment of the front and=0Arear tufnol beari
ngs/bushings with the aileron torque tube appears to=0Abe a critical step i
n preventing control stiffness.=0A=0AThere are no specific guidelines about
this on the manual. I am mostly=0Aconcerned about thermal expansion since
the cockpit can see 70C=0Adifference from summer to winter. The torque tube
is about 24" long=0Aand looks like zinc plated steel. For 70C, the thermal
expansion will=0Abe about 22 mils. So I am thinking I need to insert 12mil
shims on=0Aeither side of the tufnol bearing before bonding the fork and t
he=0Abushing, and then removing it after cure.=0A=0AThen there is also the
question of tufnol expansion due to moisture.=0AThere is a chart on tufnol.
com on how much tolerance should be allowed=0Afor water absorption. This is
for prolonged immersion so it can be=0Aconsidered a worst case scenario. F
or the 1/2" bearing, this=0Atranslates to about 0.8mm, or about 32mils.=0A
=0ASo putting both factors together, I am thinking of inserting 25mil=0Ashi
ms on both side of the tufnol, for a total of 50mil play. Does this=0Asound
right?=0A=0AAll of this could turn out to be a moot point if the flex in t
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