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PA-12 Flap Bracket Placement


Registered User
Esbjerg, Denmark
We are in the process of installing the flap kit that Univair sells, in the PA-12 project that we are building. We are having trouble with finding out how to place the flap bellcrank bracket without it interfering with the aileron cables.
Please could someone who has a PA-12 with flaps tell us how high on the spar to place the bellcrank or - even better - e-mail a photograph of the installed bracket (the whole flap actuating mechanism) in relation to the aileron cables?

Thank you.

Sorry, I don't have time to post a photo or get measurements.

However, I can say that the bracket will be very close to the aileron cable, and that I have, in some instances, installed a simple plastic block for the cable to ride on instead of letting it ride on the bracket. I have done this on -12's and -14's both. Same issue.

Good Luck. DAVE
Thanks Dave,

We have been messing around with it all day and I guess we won in the end. Nice of you to give us the idea that we might build in a new fairlead.


I am also in the process of installing -18 flaps on my -12. Have heard stories that blueprint in the day/night STC is incorrect. After looking at it and thinking about this for several weeks, I have decided to put the wing back on the airplane and make sure everything is correct before I drill any holes.

Just eyeballing it, it seems that the bracket for the flap bellcrank should go somewhere about 3/4s of the way up on the spar or as high up as you can without interfering with the aileron cables. Also, the aileron turnbuckles need to be moved from rib bay #2 to rib bay #3. On my aircraft, this means I will have to make new cables from control stick. I think the aileron control cables in the wing can be shortened easily enough.

The #1 flap hinge is also shown in the wrong position on the blueprint. I think it needs to go in the same vertical spacing on the spar as the rest of the hinges on the wing. If you dont, the flap will be crooked when it retracts.

PM me if you want.


I'm in the home stretch for installing flaps & a whole lot of other mods on my PA-12. The interferences between flap & aileron cables was resolved by installing a fairlead above the flap push-rod bracket & a pulley inboard from the flap bellcrank.

There should be some search result available on this. As said, its a close fit when its right. Although we got away without doing it, I think it was Ron Sullivan who recommended (like KJC said) temporarily hanging the wings back on your fuselage w/cable strung to see what the best locations are for bell crank and also the positioning of the pulley that welds on to the upper fuselage longeron too. As I recall that can affect some of the aileron/flap clearance issues.

We found that having the wings on the fuselage was essential in manufacturing and installing plates with fairleads to route the aileron cable underneath the flap bellcrank and over the flap brackets.
We found that the Univair ribs we had installed when we rebuilt the wings needed to be cut and modified much more than was the case with the original Piper ribs. This is partly due to the pulleys on my new fuselage not being in the optimum position. They really should have been placed .5" further aft.
It was a tight fit, but all is in there now, looking good and working fine.
Can't wait to put the fabric on.....


I would very much like to see pictures of this if you get a chance. To my understanding and according to the STC, the aileron cables run over the flap bellcrank. Did you do something different?

Hi Kevin,

Sorry for being so long in answering. I have put a few photos of the installation in the gallery:


You will notice how the aileron cable is routed below the flap bellcrank but over the flap bracket. We made some new fairleads for the aileron cable to slightly reroute it.
I am aware that much of the hardware in the photos need to be changed and that the bellcrank must be swapped for that on the other side.

PM me is you have questions or need more photos.