I've been using a Pixhawk for a while and I've never had this happen:
We calibrated the accel/compass and gyro when we arrived at the field
All sensors looked good after calibration.
On the ground all of the servos worked (tested throttle as well)
We performed 6 throttle run-ups, and sustained for 2x10sec runs. All surfaces works and the system was armed before takeoff.
We launched the plane from our catapult (~2.5G's) and right after launch we lost all servo control. After the crash, we somehow regained servo control (we tested right after crashing without arming).
On approaching the plane, there were blue/red lights flashing, however the logs don't show a reboot.
We've had this happen twice on the aircraft - once before upgrading to 3.5 and once after.
In addition, after looking at the logs, it says that the plane pretty much started spinning right after launch (IMU went total haywire - just straight up spinning) however, would this cause an autopilot reset?
I can upload the log files if people want, but they're pretty long (we go through a ton of tests before takeoff, so the logs are since then).
I'm stumped - anyone have any ideas?
Edit: I've added the logs and google earth KMZ if people want to see them:
Edit: We've flown this plane multiple times before, with this autopilot (and the same setup, transmitter...etc).
Ok - so we'll switch to the external power module then. However, some things are stil left unexplained that I'm concerned about.
a) Why didn't we need to re-arm if the Pixhawk restarted?
b) If we have dips in power, do you think that would be enough to effect our PPM receiver? We've never had issues like this before our last two flights (we've had 5+ flights with this setup).
If you are not using a Power Module, you should use a zener diode as per the instructions on the ArduPilot Wiki.
For what its worth I would add the Zener and the cap as seen in Wiki. I have seen pixhawk shut down and reboot using digital servos. Remember to power the rail with good clean reliable power because the power that is plunged into the rail is powering your servos. The power module only powers Pixhawk and will not power servos.