Recently I have been having an intermittent issue that I cannot figure out.

This has happened twice now and each time it results in a severe crash.

My heli is suddenly taking a left turn in flight and pyro's to the ground. First time it happened it was immediately after doing a full throttle/pitch punch out to about 50/75ft. It didn't start until I leveled of and was very sudden (no prior indication). It was so fast that after the fact it was hard to determine what direction it spun but I am pretty sure it was nose left. The second time it happened I had been flying for about 5 min and had done several punch outs been flying around in forward flight and even fast backward without any indication of anything wrong. Again it was fairly sudden and If I remember correctly it spun to the left again from a fairly level position (high hover).

After picking up the heli, the first time, I notice the rudder servo had been stuck where the servo horn was in the aft position (left turn). As soon as I unplugged the battery and freed up the servo with the power off and then reconnecting the battery everything seemed to work fine. After the second time it happened I couldn't find anything wrong and all servos seemed to work fine.

Sorry for you Align guys but its and EXI. I am using the xmhelicopter 401B gyro, AirTronics RDS8000 TX/RX and JR servos (DS825/DS3400 combo). One item to note, the bearings are starting to go on the main drive motor but I do not think this is the issue.

My belt tension is good and no missing teeth. All of the gear train is in perfect working order so I am ruling out a mechanical issue.

I am thinking I got a defective 401B gyro and it intermittently decides to do its own thing.

Has anybody had anything like this come up and did you ever figure out what the issue was?