Need a little help with IRISH crash log

This has happened 3 times randomly. All other flights are perfect. All 3 times I was only a few feet off the ground.

Just taking off.

Mode = Stabilize

Voltage = >12vdc

GPS Status - poor ( unusual) but in stabilize mode. in and out of GSP lock errors as reported by Mission Planner and buzzer.

After liftoff when copter is about 3 feet off the ground the left rear dips hard (like that motor quits) and it hits the ground like a rock falling.

Telemetry quits working.

Copter won’t arm.

Had to cycle power to pixhawk to get comm going again.

Noticed after reboot and arm that rear left motor is slow. Can’t take off cuz rear left motor is slow.

Execute ESC cal and all works well after that on same battery. Did 2 more flights with no issues.

Flash log is attached. I’m not an expert at the logs yet but the data seems to be dicey.

Would appreciate a log analysis from a better log reader.

Log attached.



Looks like you have a motor failure.
Please contact help@3DRobotics for an RMA

By the way, I like the name IRISH. I think that could be a good name for the next version :slight_smile:

Oops. IRISH…

I’ll contact support shortly. Thanx for the quick reply.

Could you share with me how you spotted the motor failure in the logs? I suspected it (or ESC)but couldn’t quantify it through the log. It’s intermittent. About every 4th or 5th flight. Is that normal for motors to have intermittent failures?

It seems to drive the Pixhawk nuts or is that normal once a crash error is detected?

I don’t mind changing the motor but I’ll probably order a couple more.

Thanx again,


Look at Desired roll vs roll and desired pitch vs (actual) pitch

when they diverge is when the motor failure happens

I went back and looked at some tlogs and noticed something else strange when this happens.

From the time I powered up the Pixhawk I had bad GPS performance and low signal strength on the telemetry. It was only reading 73% when they were only 20 feet apart. GPS fail intermittently. Noticed I needed more throttle to keep it up and then BAM.

When I have good telem signal and no GPS failures there are not issues. This applies to stab mode.

Could a faulty motor be causing these other symptoms?