Before you install that rudder trim tab - STOP

[Wayne G. O'Shea]

Reading another forum on broken rudder pedal return springs on Super
Cubs......

...... got me to thinking about the numerous Rebels and Elites that I've had
thru the hangar/shop over the years, that have arrived here sporting a trim
tab on the rudder.

Before you make this ugly, forehead cutting mistake, that you'll regret next
time you bend down and pick up the tail by the tail spring..

Lift the tail up and set it on a sawhorse, milk stool or what ever you have
handy. Now grab the rudder in your hand and push it fully left... fully
right.. back to center.. did the cables stay tight or did they go slack??
Every airplane I've had come in here sporting a trim tab has had one rudder
cable that goes slack (or a tail wheel friction issue). Improper spring
geometry or excess friction somewhere in the system that doesn't allow the
rudder pedal (and it's spring) to maintain cable tension. This is the
generally the cause for the need of a rudder trim tab.. not an issue of the
control surface itself, but one rudder pedal return spring pulling the cable
tight and the other one not doing so.

So before you rivet that mess on the tail... check out the cause. Also
remember when you have the cables running smoothly you can also trim for any
minor issues by tightening the spring on one side. Better there than the
drag (or cut forehead) of a trim tab.

When you go to floats/amphibs..... if you find you need a bit of rudder trim
just adjust a water rudder slightly in the opposite direction and it will
move your air rudder for you, for feet off "ball in the center" flight!

Wayne





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[ray.mason]

Anyadvice on adjusting aileron trim?

On 3/15/2011 6:08 PM, oifa@irishfield.on.ca wrote to rebel-builders:

-> Reading another forum on broken rudder pedal return springs on Super
-> Cubs......
->
-> ...... got me to thinking about the numerous Rebels and Elites that I've
had
-> thru the hangar/shop over the years, that have arrived here sporting a
trim
-> tab on the rudder.
->
-> Before you make this ugly, forehead cutting mistake, that you'll regret
next
-> time you bend down and pick up the tail by the tail spring..
->
-> Lift the tail up and set it on a sawhorse, milk stool or what ever you have
-> handy. Now grab the rudder in your hand and push it fully left... fully
-> right.. back to center.. did the cables stay tight or did they go slack??
-> Every airplane I've had come in here sporting a trim tab has had one
rudder
-> cable that goes slack (or a tail wheel friction issue). Improper spring
-> geometry or excess friction somewhere in the system that doesn't allow
the
-> rudder pedal (and it's spring) to maintain cable tension. This is the
-> generally the cause for the need of a rudder trim tab.. not an issue of the
-> control surface itself, but one rudder pedal return spring pulling the cable
-> tight and the other one not doing so.
->
-> So before you rivet that mess on the tail... check out the cause. Also
-> remember when you have the cables running smoothly you can also trim
for any
-> minor issues by tightening the spring on one side. Better there than the
-> drag (or cut forehead) of a trim tab.
->
-> When you go to floats/amphibs..... if you find you need a bit of rudder trim
-> just adjust a water rudder slightly in the opposite direction and it will
-> move your air rudder for you, for feet off "ball in the center" flight!
->
-> Wayne
->
->




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