HEXA almost crash

ArduCopter Copter 4.2
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1

Today will go down in my flight history. One of the six motors burnt out while flying over a residential area. I only avoided the crash because I am flying an X6 drone. If it were a quad, it would definitely crash into the ground, or worse, it would do property damage.

I am asking for help in finding the cause of the engine burning out during the flight. I have never faced a similar situation.

Motors: 6x Gartt ML5008 400KV
Propellers: 6x Tarot 17 "TL100D10
ESC: 6x Hobbywing XRotor Pro 40A
Battery: 1x LiPo Tattu 16000mAh 6s 15C
Drone weight: 7.3 kg

I post the log:
https://drive.google.com/file/d/1Z98WaQ6otl4bX30iCRuoT7tgKkzqFMbi/view?usp=sharing

PID:

perfect tuning
perfect tuning1267×712 223 KB

Photos:

burned gartt
burned gartt1920×1920 289 KB

x6
x61920×1920 1010 KB

2

It was going well but that bad motor (or ESC) got worse and worse during the flight, losing thrust over time.
The output of the opposite motor is reduced to compensate.

image
image1449×714 24.3 KB

I would use MissionPlanner motor test to run some tests and see if the motor or the ESC get hot.Without temperature data it’s hard to tell whether it was the motor or ESC. It could even be an ESC fault that has now ruined the motor - or the other way around :frowning:
Could be as simple as bearings in the motor - if so replace all bearings in all motors.

1 Like
3

I dismantled the burnt motor, the bearings rotate smoothly, but I’m not sure if they will behave the same at high speed. This is a guessing game.

4

Motor coils not shorted? It happened to me with an Octo, the motor burned, the coils closed short and consequently the entire power system collapsed, completely shutting down the equipment.

5

This is what the coils of a burnt engine look like:

gartt
gartt2494×2494 324 KB

6

Oh yeah! In your original picture you can see that in the motor coils, I missed it earlier.
You’ll still need to test if that ESC is OK, or dont take the chance and just replace it.

1 Like
7

I did a test of the motor temperature with a pyrometer in a home condition 27° C. I used the motor test in Mission Planner for this. During 2 minutes at 50% throttle consumes 11A and heats up to 78 ° C. I made measurements in the area of bearings.

8

It’s getting really hot, usually no more than 70ºC with payload.

9

Scorpion motors need regular oiling of the bearings. I wonder if other brands should recommend the same.

10

Bearings are usually shielded and should not be lubricated. When they reach their useful life, they must be completely replaced.

11

Well known brand Scorpion thinks differently. Specifically for their Rc Helicopter motors.

12

How many flight hours? I replace bearings and sometime motors every 1000h

13

STAT_FLTTIME= 46927s
STAT_RUNTIME= 573337s

14

Good question!
I have never used my drones or Helis commercially. I do not know the hours of each aircraft. I gave the motors usually a drop of Scorpion Motor Bearing Lubricant after about 6 flights. On the 30 ml Scorpion Bottle it says: Mil-C-81309E, Type II. Lubricant Made in USA.
I am flying as a hobby since 2010 and never replaced a bearing for heavy use. I have mainly replaced motors after a crash or started fresh with a newer or better aircraft.
I believe your practice will work but only with best quality gear.

15

Not todo much. Maybe this motor worked blocked once

16

Yes, using quality motors. In any case, in each maintenance cycle, the temperature and vibration must be checked. And if these increase find out the cause.