Troy,
The point of drilling new holes in the drive arm, rather than
extending the horn on the tailwheel, was to minimize the spread of the
cables where they exit the rear of the fuselage. The change in angle is
already pretty large (greater than the FAA's recommended maximum for a
fairlead) with Graham's original horn, and it looked as if it would be worse
with a larger spread on the horn. (The appearance is somewhat nicer as
well.) If you could find the right spots to drill holes in the rear
fuselage to route the tailwheel drive cables straight from the drive arm,
this would not be a factor. After 6 years and 500 hours, the fairleads have
not worn through.
We drilled the new holes in the drive arm at about 2/3 of the
spacing of the original holes. This left plenty of clearance on the
starboard side for a shackle to connect the tailwheel cable, but a port-side
shackle would have interfered with the rudder pushrod (which was not
changed). Instead, we fastened a short strip of metal to the hole with a
clevis pin, and then secured the port-side tailwheel cable to the aft end of
the strip, bent downward (in the direction the cable goes) to clear the
rudder pushrod.
This change was made after the airplane was flying, by removing the
drive arm through the inspection hole, adding the holes and metal extension
strip, and reinstalling the arm. We had made quite a few flights off of
pavement with the original setup, keeping the springs lightly compressed per
Graham's recommendation. We felt that the springs were delaying the steering
response (which was quite sensitive as well), making it harder to get just
the right amount of rudder input without overshoot.
Dave DeFord
N135TD
> You said:
> <<Rather than extending the steering horn on the tailwheel, we
> moved the attachment points for the tailwheel cables closer to the pivot
> point on the control arm at the rear of the fuselage. Our steering
> sensitivity is now similar to the factory setup, about the same as what
> you
> would get with William's recommendation.>>
> What was the advantage of this over doing it outside where you can have
> better access? Did you just drill a couple holes and that was it? I too
> have Graham's mod and had forgotten this had been suggested a few years or
> months ago.
>
> Troy Maynor
>
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