Hi Avedin,

I would suggest making sure first thing that your Gear channel is nulled in AUX channel.
Next, do a Pmix with Throttle as Master, Gear as Slave, leave the stick assignment NULL and set your percentages at +100% both ways.
Now, do a 2nd mix with Throttle as Master, Aileron as Slave, again leaving the stick NULL and setting the percentages to +100% both ways.
(If you are wanting this mix to be activated by a switch, then in both setting select the same switch and on position.)
You may need to make these percentages, a negative amount if your are not getting the direction you want from your flaps.

This sounds as though it may be what you are looking for.

I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.

Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician