Unexplained fall from the sky.

[_milo_]

If you were just hovering, that some really high amp draw, was it crazy windy?

I'd check your motors, power off, spin them listen/feel for resistance, griding, etc.

If its all good, if your mavic still works to power up, power up with props off, arm and throttle up slowly, listen, feel for vibrations.

Then arm, and as fast as possible, throttle to full position, try this couple times, then throttle back to low, ESCs can loose sync when the power is raised suddenly, causing a crash like yours, although I've not heard this happening to any Mavic, ever, but its worth a check.

 

[MisterMavic]

Hey I appreciate all the info and insight.

 

[MisterMavic]

No I don't even think I ever got a wind warning. I was just cruising over the neighborhood when it all went south. All my props were in A+ condition as I check them preflight. If one failed It would be hard to say as 3 of the 4 were broken when it crashed. I took the drone out and tested it again today keeping it to just a few feet off the ground but I pushed it pretty hard to test it. All seems normal and fine. I never crashed the drone in the month or so I've had it and I don't push it real hard, but I am not going to push it all from now on. Easy does it is the word. Gotta say I'll never feel completely safe until I have some sort of answer though. I may end up sending it off to be looked at and tested.

 

[_milo_]

Upload your test flights to airdata, and click the side, where it says power, then click the top tab under voltas, and amps. You can click on "flight specific full range amp map" that will give you more detailed current draw.

I've looked at my flights, and I've not had one flight where I went over the green (10 amps), now granted I don't fly my Mavic much in sport mode, but even flights where I hit over 40 mph, my amp draw is all in the green, below 10A, maybe someone who flies there Mavic more aggressively, can chime in. I have other quads for that sort of thing.

Please check that data, its really easy to see in airdata, if your hovering in stable wind and its pulling big amps, something is not right, and I would be contacting DJI.

 

[HFMan]

He was flying in Sport mode, his amp draw in sports mode is not unusual at all. This was not a battery problem, I am certain of that. Nor was it a temperature problem... it simply experienced some kind of flight disruption, and failed trying to arrest the anomaly. I guess you could consider it a semi-controlled crash at best.

 

[HFMan]

Prop or motor is what I was thinking, looking above is that the power of each motor, RFront 80, LFront 9.9, LBack 8,563 and RBack 9892? Do the values of the RFront compared to the LFront look right?

That was simply the motor power at the cursor position. As I said, it was chaotic and the motors were all over the place (but it all was preceded by some kind of external disturbance like a bird, pole, powerline, or broken prop).

 

[MisterMavic]

That was simply the motor power at the cursor position. As I said, it was chaotic and the motors were all over the place (but it all was preceded by some kind of external disturbance like a bird, pole, powerline, or broken prop).

I would have to go with bird strike or broken prop since I was probably 100' over the highest object.

 

[Sencorp]

I didn't look at the DAT file, that will narrow it down a lot more, but I did note, that you were pulling some much higher amps, then I've ever seen on my flights, and your battery temp was higher than I've ever noticed on my flights.

You started with less than full battery, were you flying aggressive in sport mode? If not I'd check the motors are spinning freely, no grinding, or binding.

Looks like battery pushed past its limits, but the Cyber should have more from the DAT file.

I'm on this as well. That bat temp skyrockets just before the fail. I suspect it was a bat overheat protect. Not sure but I will come have a better look at the data tomorrow.

 

[BudWalker]

This incident was not caused by a battery issue. There were no battery warnings. The battery temp had been climbing gradually and had reached 46C, not that unusual. The flight started with the battery at 92% and was at 36%. The current had been peaking at 22 amps, normal for Sport mode.

As @HFMan noted there was a gyro and accelerometer incident followed by erratic flight. It is different though from the usual broken prop incident. Sampling the data at 200 HZ (instead of the 30 HZ default) it can be seen that the gyro gets very noisy at 546.427 and then stays noisy. MotorCommanded starts being chaotic 0.05 secs later because it is derived from the noisy gyro data.



This is much different from the usual lost or broken prop incident. Looking at the other motor data there is no indication that a single motor/prop has lost propulsion. There is no spinning that would have been caused by single motor/prop losing propulsion. I can think of three possibilities. 1) A gyro sensor problem. 2) One of the props breaking just enough to cause the gyro noise, but still has some propulsion. 3) I don't know.

 

[BudWalker]

This incident is almost exactly like another incident that I just now looked at.

Drone crashed-- not sure what happened

I had previously pooh-poohed the idea that a battery issue was involved. But, that incident occurred after the battery temp had reached 56C, maybe a bit high. I think that's just a coincidence, but needs to be mentioned. Probably has more to do with a long flight which results in the higher battery temps.

@HFMan

 

[_milo_]

Did a flight and maxed pitch and WOT in sport, pulled DAT and the OP (current bat temp data) is normal,

The problem, I was looking at Airdata (healthydrones), and it is not capturing current, or battery temp data, even though it displays as if it does, on my logs, always shows below 10A, and batt temp is not correct either.

 

[MisterMavic]

Well I did take the Mavic up for about 20 minutes both yesterday and today, **** excitement of my Goggles was too much to handle. All went well but I will never push the Mavic near what I have in the past. This will not sit well with me without an answer. The thought that this could happen again is not a good one. A 5 pound object falling from 300' in the sky usually won't end well for someone or some thing. Would DJI even give this issue half the attention that you all have been so gracious to provide if I sent them the DAT file? If I sent them the drone what would they do besides charge me and send it back in a few weeks? I'm serious when I say the Mavic crashed from over 200' without a single scratch. Very lucky even though I don't feel lucky. Yes the Mavic came away without a scratch and flys like the day I received it but........

 

[MisterMavic]

Came across a message posted on DJI's forum about Mavics falling from the sky happening with Mavics produced in March. It had a link to enter your serial number which gave you your production date, mine was March 13th. I opened a ticket today.

 

[MisterMavic]

My post was "Unexplained Fall From the Sky" in Mavic Pro Discussions.

 

[Dyso_70]

I had a similar issue although my MP was destroyed. I sent it to be repaired and DJI claimed it was a motor malfunction and replaced it free of charge.