[onecooler]

Hi folks!

Last weekend I got my 250 quad flown away at about a full throttle. My feeling is that CC3D got some problem and frozen at full throttle for a couple of minutes. The most stressful part of this incident is that I was flying FPV and could observe my quad flying high until it crashed a couple of kilometers away. 
I had fallsafe setup on CC3D to cut throttle off on signal loss. My transmitter fallsafe was set up the same. Previously at signal loss the quad would just fall down right after signal loss, but this time it took a lot before it shut down the motors. I got a DVR recording of this incident:

Turn sound off since there is only static. Fly away starts at about 1:30. Motors cut off occurred ~ 1 minute after.
I found preliminary area where it has "landed", have gone there spoken to people living there but they have not noticed anything falling from the sky. I left my cell in case they find anything that is left from drone or if they discover any damage related to its crash.
And a usual rhetorical question that is asked in such cases: how can I avoid such flyaways? What may cause it?

Thanks in advance,
-K.

[nitromethane]

Sorry for your loss

First, a tester or a developer would try to reproduce a flyaway condition in a safe manner on the ground with a quad tied to a heavy brick or something like that.
Another great step would be to try to document the conditions (setup, settings, log files...) at which a flyaway condition occurred, so other people my try to reproduce it.

Next steps would be to try and narrow down a list of possible causes and create bug reports if needed, so code wizards can keep track of it and eventually fix it.

[onecooler]

I will definitely try to reproduce this flyaway if I ever find my drone 

[Mateusz]

Did it happen only with this copter or any other ? Do you have another build that behaved like this? Really strange.

[onecooler]

Only this one. Strange is a wrong word, I would say mystical. I would understand if it would fly until it drained battery to 0, but it did turn motors off... too late but it did...

[Mateusz]

Fail-safe kicked in when you lost radio signal. There are two fail-safe one by receiver in frsky and one on flight controller afaik.

[onecooler]

There are two fail-safe one by receiver in frsky and one on flight controller afaik.

I use spektrum and my receiver fail-safe is also setup for 0 throttle.
I only hope that my revo setup will not do the same. 

[Mateusz]

There are people including me that fly regularly no issues like that AFAIK. If no one can reproduce this, then it's hard to fix especially if it's not obvious which part failed and why.

[onecooler]

There are people including me that fly regularly no issues like that AFAIK. If no one can reproduce this, then it's hard to fix especially if it's not obvious which part failed and why.

Sure, I clearly understand that! Moreover, I believe this may be a hardware issue as well. We can only hope that I finally find this drone and do the testing.

[nitromethane]

I read, you use spektrum, is that a full on receiver connected via PWM/PPM or a satellite receiver conected via serial?

It seems to me that FC kept doing its job and something got messed up on the receiver side and kept sending rubbish commands to the FC.

[onecooler]

I read, you use spektrum, is that a full on receiver connected via PWM/PPM or a satellite receiver conected via serial?

Hi! It was pwm reciever not a satellite. However it was not an original spectrum receiver.

It seems to me that FC kept doing its job and something got messed up on the receiver side and kept sending rubbish commands to the FC.

It does make sense. On the dvr recording it was moving around yaw axis but keeping the same angle. It may happen that controller was receiving some rudder signal. But there is still question why motors got suddenly shuted down?

[nitromethane]

Could it be possible that something got f***ed between the Tx and Rx or maybe even at Tx and the Rx kept outputting whatever it taught was the command from the Tx until the signal dropped due to distance and failsafe properly kicked in?

[Mateusz]

But there is still question why motors got suddenly shuted down?

Motors shut-down when fail-safe kicks in, due to lost of radio signal. This is normal in most cases under default settings, when you are out of range copter should fall.

[TheOtherCliff]

old thread, but a comment:

It's very important to understand that there are two failsafes.

For the RC system, that is the receiver putting out servo positions that are previously setup somehow (when it goes out of range).  This can be set e.g. to reduce the throttle to bottom to shut the motors off and fall.

If the RC system is designed or set up to simply put out the last set of servo positions that it received when out of range, then it is a fly away waiting to happen and no other amount of configuration will help it.  The best you can do is hold the transmitter up over your head to try to get a better signal to fly it back into range.

If the RC system is designed or set up to stop sending servo pulses when it goes out of range, then the FC failsafe runs and the default for that is shut the motors off and fall out of the air.  This default can be changed using the System page in 15.09 but there is a GUI setup in the next release (16.06).

It is very important that you understand what your RC system is capable of and how it is set up and to set it up the best way you can given it's capabilities.

[onecooler]

Folks,

It appears that this flyaway was completely my fault. The receiver I used in that build was spectrum compatible S603 and today I was setting up the same one on a new 210 frame. Failsafe on this receiver must to be set in a bit different way then on genuine spectrum ones. If you bind it with a bind plug inserted it will be sending last known signal when signal is lost. I was 100% confident that I have checked failsafe before flying, but now it appears that I have not. 
Do not repeat my mistakes - always check failsafe on the ground with props removed, and read receiver manual carefully!

-K.