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Estate RV-12 flaperon issue.

Greg Bradley

I'm New Here
Hello all,

I need some advice or help...

My good friend, RV-12 builder, Doc Ireland passed this winter and left his RV-12 in his estate. I have flown it and found that with flaps down the right flaperon is deflected more like 5 degrees with the 2nd notch of flaps. Aircraft banks right when flaps are lowered.

I have read some historical comments here and considered all cures to this problem but want to eliminate the easiest first and continue until fixed by an A and P mechanic.

This aircraft has the servo'd autopilot and was first wondering if any linkages from the servos to the control could need adjusting?

I noticed too, that statically, when I put in one or two notches or flaps with stick centered, as flaps are engaged, the control stick moves a unit to the left for each detent. Is that normal?

Thank you.
 
Some experience with these issues - -

I would start with taking the rear floor tunnel covers off. ( yes, may be lots of work if tank has to be removed ). I worked on one that had been set up completely wrong. If you have the builder manual, lock the controls as instructed, and go from there. The flaperons should be equal at that point. If not, follow the instructions in the build manual.

ALSO - check the AP servo linkages. They may be off also. Off, as in dangerous.
 
Everything John said + remove the seats and the seat inspection panels and measure all he rods that are built in section 32 - flight controls
 
I agree with John as well.

I suspect that if you first look at the control horn arms on the inboard end of the flaperons, you will find that they are not exactly aligned with each other when the ailerons are neutral.
 
It does sound as though there may be an assembly and/or rigging issue. I'd follow the advice given. Pull the floor panels and inspect. Lock the controls per the assembly instructions, and see if the pushrods are the correct length and the flaperon torque arms and torque tubes are installed and drilled correctly. It's in section 32 of the assembly manual.

On the one I bought, they are not. The plane flies straight and everything works, but one pushrod bumps against the fuel pump at full aileron deflection. Just enough to feel the "bump". We'll be fixing that.
 
The distance between the left and right stick grips does slightly change with flap position.
 
Due to the geometry of the aileron/flaperon mixer the sticks move somewhat during flap extension/retraction. From what I remember the sticks come together when you pull flaps (you don't notice during actual flight). So if you hold the left stick in a fixed position during flap extension the right flaperon will drop more than the left. If you hold the right stick the left flaperon will drop more.
 
Due to the geometry of the aileron/flaperon mixer the sticks move somewhat during flap extension/retraction. From what I remember the sticks come together when you pull flaps (you don't notice during actual flight). So if you hold the left stick in a fixed position during flap extension the right flaperon will drop more than the left. If you hold the right stick the left flaperon will drop more.

Is your description of flaperon function normal then? I am not a builder. but have noticed similar differences, and don't want to fix something that doesn't need fixin... Sounds as though the difference in individual flaperon positions are offset by in-flight aerodynamics or something to be anticipated and trained on WRT stick and rudder techniques??
 
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