FredG Posted January 8, 2017 Report Share Posted January 8, 2017 2006 CTsw, experimental registration. About 900 hrs TTAF. Lots of time in the pattern, with about 2700 landings. About a month ago, the plane developed an intermittent flap control failure. Specifically, when the flaps switch was rotated to extend the flaps, nothing happened. This typically happen when going from 0 to 15 degrees and from 15 to 30 degrees. It could be resolved by quickly switching to retract the flaps (which worked every time) and then back to extend the flaps. It never happened on the ground and it didn't happen early in a flight. It also didn't seem to affect the operations manual side of the switch (up or down). I checked all connections and none appeared to be poor. Based on prior reports of problems with relay board (the board on the firewall), I put my hand on the board and operated the flaps (on the ground). I could feel the relays operating, but, with only light finger pressure on the board, I could stop the flaps from operating. Releasing the pressure and the flaps would run. The stoppage occurred both on extension and retraction of the flaps. I removed the relay board. Removing the board is not fun. First, the two screws holding the board in place were screwed into rivnuts in the firewall. FD (I believe) used a thread locker on the screws and one of the rivnuts spun in place. In addition, the seven connectors on the board are held in place with very secure screw terminals. But, FD (I believe) put a sealer on the screw heads that had to be removed before the connectors could be removed (the sealer fully loaded the slots in the screw terminals). All of this was done with the board in place against the firewall. Once the board came out I could see on the back of the board that one of the soldered connections had failed. See attached photo. I cleaned the lacquer from the failed connection and re-soldered it. Note that it is important to not bridge the solder to a nearby circuit board conductor. I then applied paint to the newly soldered connection and re-installed the board. It worked on the ground, but it worked on the ground previously. A test flight yesterday showed no in-flight failures after five landings (and some air work). I will test again today. This problem has been reported by others on this forum. Still, given this failure, I thought it might be worth mentioning again. Fred Link to comment Share on other sites More sharing options...
Roger Lee Posted January 8, 2017 Report Share Posted January 8, 2017 Some boards have developed cracks in solder joints over time. Some people have been able to find and fix these while others have had to replace the boards. Vibration is a killer. Link to comment Share on other sites More sharing options...
Runtoeat Posted January 8, 2017 Report Share Posted January 8, 2017 Fred, good info to repeat for those of us who might not have remembered a previous reported failure of this component. How did you finally get the fasteners loosened which held the board to the firewall. Did you use some heat from a hair dryer to soften the loctite? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 9, 2017 Report Share Posted January 9, 2017 It seems FD could have mounted this board to some rubber isolators and kept vibration from being so deadly to this board. Or at least done it to new airplanes after they had seen a few failures. Might be worth doing on ELSA airplanes, especially if you have a failed one and are there anyway. Link to comment Share on other sites More sharing options...
Mike Koerner Posted January 10, 2017 Report Share Posted January 10, 2017 Actually, a circuit board like this belongs in an enclosure - it's own little plastic box with strain relief on the external wires, or better yet a fixed connector (I had one of the wires break off mine). Mike Koerner Link to comment Share on other sites More sharing options...
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