HI,

I have been flying a Ultra Stick 1.20 for a year and a half now (100+ flights) with no problems until yesterday. Yesterday while flying I had a sudden loss of control and the elevator servo twitched down for a split second, also the engine would momentarily go to idle. While flying I noticed that this happed only when the plane was pointed toward me. (EDIT this would put the receiver directly behind the ignition box and engine from the transmiter location) The engine going to idle I figured was from loss of signal and the fail safe setting kicking in??? Later the same day I did fly another plane with the same transimtter with no problems at all.
Last night I changed out the receiver with one that I have used many times with no problems. Today I flew one flight with no problems at all and about 10 minutes into the second flight the elevator servo twitched again and the plane was to low to recover.

Also every time I had the twitch the plane was at full throttle.

After the crash the servos and receiver all worked fine, I do not think the switch is bad.

Plane: Ultra STick 1.20
Engine: Zenoah G26 electronic Ignition
Ignition: CH ignitions
Transmiter: 10CG ( New about 2 months ago ) flown about 25 flights on various planes with no problems
Original receiver: R617FS bought new never crashed or damaged, Never had any problems until yesterday
Replacement receiver: R617FS bought new never crashed, used many times in various planes
RX battery: 2cell A123 fully charged checked out ok after the flight
Ignition battery: 4.8 NIMH no problems
Elevator and rudder servos: Futaba S3050
Aileron servos (4): Futaba 9001
Throttle servo: Futaba 3004


Please let me know what you think could be the problem. I am currently building my first 50cc plane and am very concerned about having the same problem in that.

Well, considering the fact that the A123 battery pack is not one of the types recommended by Futaba, we'd really not know what could have caused the glitching. Futaba recommends using 4-cell or 5-cell packs of NiCd or NiMH chemistry. They have no recommendations for other types of battery pack chemistry.

For most models, failsafe events or glitching is caused by voltage difficulties in the system. Something could be causing the system to have large voltage drops. Momentary loss of control could be caused by a variety of things. The only thing that's common is the airplane. The twitch happening at full throttle indicates a possible vibration difficulty. Vibration can affect nearly everything in the airplane, from the servos, to the battery, to the receiver, to any switch(es), connectors, and so forth. Isolating such a difficulty, especially after a crash, is not particularly easy.

We can check your equipment, but cannot predict costs if repairs are needed. We really cannot guess what the actual difficulty may be.