"Arild,     Great that you found the cause.  I saw another user here in Japan yesterday who had some bad behaviour that was related to a faulty receiver.  Replaced the receiver and it was all fine.     …"

"Hi - I know the thread i old, but I thought I cold give a final note on what the problem was. I am sorry I did not write this earlier but I saw some posts about twitching in another thread and so I remembered to update this old thread. By powering…"

"It's always been a little dodgy. I blamed the first crashes on loose propeller adapters and poor motor connectors, but it may have been the same problem since day 1. "

"@Jahn Otto I am still wondering why this APM needs a second battery while others can run from the BEC in one of the ESCs.... Did the quad flip over surprisingly when it was new, or was this behavior something that developed over time? Arild"

"I know ;-)"

"Just joking -- I'm busy with my new helicopter ;-) "

"There was one other thing I forgot to mention in my update.... I do not know if it matters. But I discovered that one of the components on the GPS-adapter was missing. So I removed the GPS before the indoor session yesterday. New adapter-board is…"

"No, I have to use a BEC, because if I use one of the BEC in one of the ESC, I power the APM from the same battery as the motors. I wanted to power the motors and the APM from two separate batteries. ....hmmmm..... I am not sure you want it back…"

"My personal view is, 'yes' for heli users.  I can't remember what version of the ppm hardware is going out from 3drobotics in the current boards but i'll double check.  For me, I never saw the problem on my quad..I…"

"So should we all change the PPM firmware? "

"Excellent news that the problem is fixed!  I delayed a long time before updating my ppm software..it always seemed like it was too core to change...but I'm also very glad I did."

"So you got it working? Cool! Can I buy it back, please? ;-) You don't need a separate BEC. You can use the internal BEC in one of the ESCs. The reason I have a separate BEC was that I wanted to test whether it solved the problem. "

"Hi! Just an update to everyone find this thread with the same symptoms. I bought the quad from OP as spares to my ArduCopter Hexa, but before I took it apart I did some tests. The quad behaved very strange - it was rock solid stable in stabilized…"

"maybe you should update your ppm encoder firmware on your APM1 or APM2.   I can't guarantee it'll solve your problem but it might."

"http://youtu.be/pDcoh-uH83M this is the vid before crash"

"I will give it one last chance. The new carbon frame is coming, hope everything goes well. If it crashes again, I go for a DJI."