I used the Nyrod system from cockpit to the elevator trim tab on my KR-2.
This system is a type of plastic Bowden cable. Both ends of the sheath must
be firmly anchored to the fixed structure of the aircraft or the trim tab
will not function properly. The anchor point on the sheath at the
horizontal stabilizer broke loose from its epoxy flox bond some time prior
to rolling on first flight. The slightest stick movement would cause the
trim tab to move to full down deflection and stay there, resulting in max
nose full up movement of the elevator. That happened right at lift off on
first flight. The aircraft would have done an inside loop had I not caught
it and forced the elevator down against the approximate 10 pounds back stick
pressure. Trim control was useless. I made two circuits of the field in
this condition, pushing more or less on the stick, to determine the control
I needed for an emergency landing.
Back in the hangar the condition could be duplicated over and over until the
broken sheath connection was found. The fix was to clamp the sheath firmly
with 2 Adel clamps. Subsequent flights had smooth trim control; I could
easily fly pitch maneuvers with just the pitch trim control.
Sid Wood
ex-Tri-gear KR-2 N6242
California, MD, USA
---------------------------------------------------------------------
Hey guys; this weekend if the weather cooperates I am going to try to
correct an issue that I?ve had for quite some time now.
It seems that my elevator trim is not doing its job properly. Whenever I am
flying by myself, the plane will nose over slightly when I release the
stick, even with full up elevator trim. When I have a passenger, and am
approaching gross weight, the issue is still there but not nearly as bad due
to the CG being further aft.
I took a look at my trim last time I was up at the hangar, and even with
full up trim, the trim tab moves a lot. I understand it is supposed to move
slightly as the elevator travels down and up, but this feels way more
?loose? than anything; I can basically move the trim tab full deflection up
and down at all times, even with full up trim.
I was curious if anybody has had this same issue, and if so, is there an
easy fix for it? I?ve essentially just ran out of elevator ?up? trim.
Would this just be a matter of tightening the trim tab cable so the trim tab
is more sturdy, or is this something aerodynamic related to the Stock KR2S
that would require major modifications?
I do not mind having my hand on the stick the whole time, but my fear is if
the elevator cables were to ever fail in flight, I would have zero
redundancy for the flight controls. If my trim tab was adjusted correctly,
and the cables were to fail, I could (in theory) use the trim tab to give me
some influence of pitch and at least make an effort to get to a runway.
Any help would be greatly appreciated.
For reference;
-Stock KR2S; RAF48 airfoil.
~650 lbs empty
-Revmaster 2100D; battery forward of firewall
-CG is near the forward limit when completely empty.
V/R
Sam Spanovich
N6399U
74S, Anacortes WA
------------------------------
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