Recent inspection has revealed excessive play in our port tailplane. The
problem is play in the torque tube pin. We incorporated Mod 62 (larger
pins) during our build so that's not an option.
Our Tech Counselor suggested using AN386 taper pins. He said they are
commonly used for similar applications in certificated aircraft. AC
43-13 confirms that AN386 pins are used in joints where "the absence of
play is essential".
A search of this forum suggested that the inner tube (TP4) would crush
and bind in the bearing (TP11) if tapered pins were used. Our thoughts
are to Loctite a 12" length of 1.375" OD .093" wall 4130 steel tubing
centered inside of TP4. This would prevent the crushing of TP4 and 12"
allows it to span the TP11 bearings. We would use a machine shop to
accurately make the tapered holes for AN386-3 pins. The tapered pins
would be installed vertically since there is not much material left on
TP9 (the center bracket) from the installation of 3/8", Mod 62 pins.
In the original design, the pins also locate TP10 sleeves against TP11
bearings inside the fuselage to prevent left - right torque tube
movement. We would like to locate TP10 independently of the pins. Our
thoughts are to machine TP10 sleeves to fit outside the fuselage between
TP12 and TP11 to achieve the same purpose. Alternatively, we could split
or slot TP10 and secure them to TP12 inside the fuselage with hose
clamps (Oetiker style for 360 deg contact).
Comments?
Jim & Heather Butcher
N241BW XS, Mono, 914
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