The accelerometer error can sure be a nasty problem. A little fuselage flex and pcb twist and the accelerometer tries to level something thats not there. It goes into auto level because it sees no flight commands when it initially does it and away it flies trying to correct a problem that does not exist. It almost always happens from a stable hover or going to a no TX output state. This happens with all flight controllers that are assembled improperly around the globe. The Blade 350 pcb has a larger through hole under the bottom of the acc/gyro to facilitate solder overlfow. What they should have done is solder masked this whole area and just used the 24 pinouts to secure the MPU-6050. The data sheet for this component explains this all but it appears manufacturers cant read. 

 Below is the data sheet link and start reading pages 42-43

 DJI still doesnt know why its happening. I read an blog post by one of the DJI repair centers they had resorted to smacking the PCB onto their bench to get them to initialize properly. This 10,000g load causes the internal mechanism in the gyro to possible tweek and center itself bending the fine conductive leads.

Why do they fly away?    What happened?

Here is what it should have looked like properly silk screened to prevent thermo electrical stresses. The component is removed in the picture.

This flight controller was abandoned before my services where offered and had fly away issues and has a clean through hole. The component is removed in the picture.

 Almost everyone experiences a flyaway. Its bound to happen, its a matter of probability. But why does it happen? There are too many reasons to list, but a few of the common reasons are.

1. The compass begins to fail before giving the user a fault signal and causes the flight controller to become disorientated because of conflicting info with the GPS. The Blade and the DJI series have this issue and its something that can be caught easier with Blades compass error detection.

2. ESC failure can be a nightmare without proper testing equipment. If you cannot induce load and examine the esc through thermal imagery you cannot diagnose a failing esc before it happens. The failing esc has higher resistance and begins to get hot and that motor receives less power, the flight controllers gyro begins to up power to keep a level flight while the failing esc's power output  stays the same causing the craft to tilt and off it goes into the horizon. Or the craft simply noze dives into the ground at high speed.


Here is what it looks like with the component back in place and the bottom heat pad cleaned of solder

Below is a plugged through hole that resulted in a  flyaway and Accelerometer error  but was recovered and sent to me for repair. The component is removed in the picture.

3. Oscillations and vibrations. Motor  vibrations can induce emf signals that the esc may interpret as brushless motor EMF signals and stall your motor and even make it run backwards or overheat. These vibrations traveling through the body make their way to the flight controller and just imagine what kind of influence that has on a gyro stabilizer built into the flight controller. The dreaded flip of death that has claimed so many aircraft.  Balance those props!!!!

4. EMI, electro magnetic interference. This can be caused by outside sources or by additional flight gear. FPV , or first person viewing transmitters can over whelm flight receivers. Compass errors can be induced by gimbals and brushless motors. Tracking units and cameras can operate on nearly the same band as GPS.  when you experience lock out there may be nothing you can do but watch it fly away.

 I test all completed drones/multicopters that I build for all of the above. I hope to save someone the grief of watching their money fly away.