T960 Hexa engine #4(C) failure

joosttromp · May 2, 2025, 7:13am

Hi all,
I’m new on the forum after a couple of months of lurking around. I’ve built a hexacopter on a Tarot T960 frame with details below.

After a quick hover test, and a small flight test i went on to do the autotune, which took a couple of batteries because i was constantly repositioning due to the wind in AltHold mode, but eventually completed successfully. Right after that flight I was seeing how the the autotune performed.

That was where I was hearing rattling noises and soon after my engine #4 (C) failed. The motor came loose in flight! when I looked up Ardupilot had already switched the motor off and the craft started spinning.

The damage is all-in-all not too bad. The reason for flipping over upon landing is mainly because I was trying to avoid the water.

In short, the reason for the engine failure is according to my investigation a combination of:

Foldable props vibrate heavily (when not fully extended)
The latest Tarot motor mounts have damped/floating carbon plates
Lack of loctite & incorrect screw length

I will address these issues by going to a 17x5.8 fixed CF prop, remove the damping in the Tarot motor mounts and re-assembling all with loctite and checking screws.

Now, I have tried to be meticulous setting the aircraft up, but I haven’t used the methodic ardupilot configurator yet, which I intent to fully perform before the next flight. I only discovered it about a couple of days before this flight.

My main takeaway is that I want to learn as much as possible in general but in particular from this event. Thank you all in advance for your tips & tricks!

Logs: 2025-04-30 18-35-27.bin - Google Drive
Video: https://www.youtube.com/watch?v=F3cGFyyDKvw

Details:
Frame: Tarot T960 Hexa X
Motors: T-Motor MN5009 400kv
Props: T-Motor 16.2x5.3 foldable
ESCs: Sequre 2670, AM32 v2.18 BLv14
C/G is around 1-2cm aft of the center of the frame.
Battery: CNHL 6S 10,000mah
Autopilot: CUAV Pixhawk v6X
Firmware: Ardupilot v4.6.0 beta5 -bdshot
AUW: +/- 5kg (w/ battery - w/o payload)
GPS: Holybro Mosaic-H Dual Antenna
FPV: Caddx WS Avatar GT + GM3 gimbal.

backup_30-04-2025.param (23.6 KB)

dkemxr · May 2, 2025, 6:24pm

Shit hit the fan when ESC errors occurred after you hit Stabilize as you can see here vs the Yaw spin (or graph Motor 4 output). The ESC Instance numbers don’t match up with Outputs but I believe ESC11 is Motor output 4 and it’s at 90%.
Try Dshot600 and reduce the SERVO_DSHOT_RATE from the quadruple loop rate you have configured. Someone else may be able to suggest the best configuration for those ESC’s on AM32.

As an aside you should have set the vertical acceleration controller gains and configured the notch filter before running Auto Tune.

joosttromp · May 2, 2025, 6:44pm

Thanks Dave that is some really valuable feedback! I was running Dshot300 but indeed quadruple rate, I’ll turn that down. Thanks! I’ll also look into the notch filter and vertical acceleration control gains.

I’m sorry I hadn’t pointed out in my first post that the motor came off in flight.. It was only hanging by the last screw. Testing full throttle punches in Stab was the nail in the coffin I guess.