This saturday I was about to make the first flight of the day on the F-15I and when I checked the commands while taxiing for takeoff I found something strange .. while the elevator throw seemed fine, the aleiron movements looked like 1/3 of the usual travel!

Ok, I aborted the flight, shut off the engine, and checked for the dual rates, atv´s, mixes looking for something that could made this happening.. nothing was found, and after doing this the elevons travel returned to normal! of course I packed everything and didn´t flew that day (it was a spectacular sunny saturday here.. a real pity).

Later at home, as the problem was happening in a elevon setup, I discarded a problem in the airplane.. so I disassembled the radio (a Futaba 9C) and found this killer detail: The yellow wire (signal) from the aleiron stick potentiometer was almost broken!!! (sorry for the cell phone crappy pic, but you can see a spot in the wire, as the broken part). This broken wire was messing up the voltage reading from the potentiometer, and almost cost me a plane.. fortunately I was lucky again and didn´t crashed the F-15. A interesting thing is that this radio is not old at all (bought it in 2005) and it was not heavily used.

So, I have a suggestion for everyone reading this:

1) Check the flying surfaces carefully before every flight. (not just moving them.. watch very carefully if something didn´t look right)

2) Check for the TX potentiometer wires if you have a Futaba radio bought earlier than this or about this same year.. of course, sending the radio for a checkup could be a
good idea. I also suppose that this applies for any brand...



Hope that this may help someone,
Enrique

you're right - it is a crappy pic!!

Good thing you decided to pack up and check it out at home...

You have been living right! Your karma is excelent to still have that plane!

Enrique, could you tell how/where the wear (abrasion?) happened?

I have been impressed with the workmanship of Futaba radios, so I am suprised it had this abrasion.

absolutely... It was disappointing at the moment, but it was the right thing to do.. much better than posting here a crappy picture of a meteor crater instead..

Good call Enrique, crappy picture for sure but, now I will have to take mine apart to check the wires in my 9C, I have seen this before in Futaba radios.

Matt, I guess that I had lot´s of luck until this moment.. there is a billion things that can go wrong in a r/c plane and more than once I had enough luck to find the problem before it happened. Hope this continues!

About the broken wire I think that it is not abrasion that caused this. There is a connector in the potentiometer board wich pulls the three wires real tight from a plastic support wich guides the wires away from the stick mechanism .. seems that this support crunched the yellow and red wire and after some up/down cycling of the throttle stick the wire suffered fatigue and started to break.

This problem seems to happen with the aleiron if you are using mode I or rudder in case of a mode II transmitter.. I suppose that it didn´t happens so much with the elevator stick as it is often more around it´s center compared with the throttle stick, but even so it is worth checking it too.



Carlos: this same thing happened to me with a old Futaba 8UHP radio, (and it costed me some helicopter parts, LOL) but I didn´t took it as a serious issue because it happened in a very, very used radio mostly with helicopters in wich I actually abused all the sticks with crazy movements.

I learned the hard way (several times, most recently my F-18 at Fresno Jet Rally in 2004) to check for full throw, proper direction, etc.. before start up and again before pulling the taxi tank.... looks like you dodged a bullet this time! Glad you found it before takeoff...

Barry

I can't help it....lol.....Futaba....[:'(] jk I know it could happen to any type.

This hobby is merciless as full scale aviation... sorry to hear that happened with you in the hard way, but at least we have fun flying this things with both feet firmly planted on ground, and when they crash we are still able to resume the learning..


By the way, I just fixed the radio with some spare wire and shrink tube.. the problem was solved. The wires where donated from a JR servo , so I will not have any problem with this radio again!