P3P Falls from Sky for No Reason

[Vertigo]

DJI marketing really makes this confusing. The "active braking" setting in the app, mostly does whats been said a few times: giving thrust in the opposite direction to stop faster. Its how aggressive position hold works.

That said, while I used to think the opposite, I have seen good evidence the phantom 3 does indeed have regenerative motor(/esc) braking too. Not as dramatic as on 3D quads, but the same idea. And there is even some correlation between motor braking and aggressive position hold: if you are moving forward at top speed, say -45 degree pitch and you want to stop quickly, you need to change your attitude to +45 pitch asap. You do that primarily by increasing thrust on the forward props, but it also helps ( a tiny bit) if you can simultaneously brake the rear props for a fraction of a second, during the pitch rotation.

All that said, I doubt this has anything to do with the OP's incident. Looks more like a ESC or motor failure to me, since it happened over a span of many seconds

 

[BudWalker]

@Erised I thought some more about your comment and I think you're right. IMHO the prop/motor/ESC issue started somewhere around 243, possibly as early as 241. It was about this time the P3 started flying erratically.

Here the GeoPlayer is zoomed in farther than it can get imagery. Up to this time (242.75) path was smooth. After this time the path became erratic.

I had originally thought there was enough control stick input to cause the relatively minor yawing, pitching and rolling at 242. I've changed my mind after making an improvement to CsvView to get a better look at the control inputs.

The elevator was pulled all the way back, but there was no other input except a small amount on the aileron. IMO there was no input that would cause the P3 to yaw.

The improvement to CsvView mentioned above will be in the next release. It can be obtained before then by installing a different txtPlayers.pml - it doesn't take a whole new install. PM me if you want this file.

 

[Erised]

@Erised I thought some more about your comment and I think you're right. IMHO the prop/motor/ESC issue started somewhere around 243, possibly as early as 241. It was about this time the P3 started flying erratically.
View attachment 65054
View attachment 65055
Here the GeoPlayer is zoomed in farther than it can get imagery. Up to this time (242.75) path was smooth. After this time the path became erratic.

I had originally thought there was enough control stick input to cause the relatively minor yawing, pitching and rolling at 242. I've changed my mind after making an improvement to CsvView to get a better look at the control inputs.
View attachment 65056
The elevator was pulled all the way back, but there was no other input except a small amount on the aileron. IMO there was no input that would cause the P3 to yaw.

The improvement to CsvView mentioned above will be in the next release. It can be obtained before then by installing a different txtPlayers.pml - it doesn't take a whole new install. PM me if you want this file.

What IF....Around 241 a motor bearing is starting to fail, as temperature rises in the bearing and the internal clearances are almost null, the ESC ramps up the amperage to maintain RPM, works for a few seconds and the slowing of the motor permit some temperature decrease and a bit less siezure, that works for about 4 seconds, then total bearing failure is beyond recovery and the AC tries to compensate but to no avail. Just a theory.

 

[BudWalker]

What IF....Around 241 a motor bearing is starting to fail, as temperature rises in the bearing and the internal clearances are almost null, the ESC ramps up the amperage to maintain RPM, works for a few seconds and the slowing of the motor permit some temperature decrease and a bit less siezure, that works for about 4 seconds, then total bearing failure is beyond recovery and the AC tries to compensate but to no avail. Just a theory.

That theory is as as good as any I suppose. I don't know much about motors so I can't add much here. Too bad we don't have the .DAT.

 

[Erised]

That theory is as as good as any I suppose. I don't know much about motors so I can't add much here. Too bad we don't have the .DAT.

Dat would be nice. The thing that really hits me is the sustained hight amp draw before 244. When bearings fail because of lack of lubrication the thermal expansion in the raceway causes the bearing to tighten up and seize, some so tight that the jammed bearings actually spin on their shafts or in the housing. The high amp draw could be to overcome the friction in the bearing, the bearing could have siezed or the high amp draw could have toasted something else.

 

[Hao Nguyen]

Hi,

I went on vacation to Norway a few weeks back and had a traumatic experience... I chose Norway because I wanted to film its beautiful fjords with my P3P, and 3 minutes into my first flight in Norway, my P3P fell from the sky for no reason. There wasn't any wind, any obstacles, and it was flying fine for 3 minutes until it just started to spin around and fell into the lake... I am assuming it was some sort of engine malfunction for one of the engines. As you will be able to see in the attached video, it was a huge lake and I was not able to retrieve my P3P. I've flown my P3P for over a year in various situations and never had an incident like this. I have a video of the entire flight as well as the flight log retrieved from my phone, so I am hoping to prove that it's not my fault and possibly get DJI to give me a new phantom or some sort of compensation.

Could any experts out there help me prove it is not my fault? I have no idea how to read the flight log and would love to get some advice on how to proceed with DJI.

Thank you in advance.

Hi achoe, looks like your prop has flown off, your accident video just like mine when I was hovering above the sea.
Dropbox - 2016_06_26_10_10_26.mp4

If your P3 is still in warranty period. You can claim for a replacement. I've just received mine as DJI staffs stated on their forum.

Wish you luck.

Screen Shot 2016-09-07 At 17.26.38

• Hao Nguyen
• Sep 19, 2016

 

[C-Mare Pro]

Hi,

I went on vacation to Norway a few weeks back and had a traumatic experience... I chose Norway because I wanted to film its beautiful fjords with my P3P, and 3 minutes into my first flight in Norway, my P3P fell from the sky for no reason. There wasn't any wind, any obstacles, and it was flying fine for 3 minutes until it just started to spin around and fell into the lake... I am assuming it was some sort of engine malfunction for one of the engines. As you will be able to see in the attached video, it was a huge lake and I was not able to retrieve my P3P. I've flown my P3P for over a year in various situations and never had an incident like this. I have a video of the entire flight as well as the flight log retrieved from my phone, so I am hoping to prove that it's not my fault and possibly get DJI to give me a new phantom or some sort of compensation.

Could any experts out there help me prove it is not my fault? I have no idea how to read the flight log and would love to get some advice on how to proceed with DJI.

Thank you in advance.

[Edit 1]: i tried uploading an excel version of the flight log for your convenience (both csv and xls), but the website won't let me upload. Please let me know if anyone needs an excel version, and I'd be happy to send it over!

 

[C-Mare Pro]

According your flight log there was a voltage drop in one of the batteries cells. I noticed in your video there was some low level fog. The moisture may have penetrated the drone, caused the voltage drop which would have affected the speed controller as well as the compass. As we all know ...the phantoms aren't water proof. Hopefully, that will be next for DJI drones.

 

[Jeiel Shamblee]

I had the exact same kind of crash on a P3P over land. Mine spun out of control with the same kind of spinning wobble. It was less than 3 months old.
DJI never told me what the malfunction was. I don't think they knew from the flight logs. Keep your video and flight logs. It's going to be very difficult to prove much, but they should do something about it. I doubt they'll replace it without the recovered unit, but keep trying. DJI does care, their communication is just bad.

 

[Distantfire]

It' hard to say, even though others have provided some good possibilities. I noted shortly after taking off you descended 100' or so, presumably to get a better camera angle over the fjord. Did you notice the white structure to the right of your display shortly before descending. This is the last structure seen prior to the malfunction. You had circled the fjord and were heading back in the opposite direction. Again the white building, almost looks like a house trailer, this time you are closer in the horizontal aspect. There appears to be someone standing near the back corner of the building. As you pass over the figure appears to move behind the building. Less than a minute later your P3P jolts and then begins it's fatal tumble. I don't know Norway's postion on firearms but it is possible that someone took offense and did the unthinkable. I live in rural part of the South. During hunting season I take off and climb to 400' before horizontal rotation.

 

[kphantom]

If you have a voltage spike, most likely it was from the esc pulling less power and like a motor stopped working and pulling current. But most likely an ESC failed or a wire came loose. So instead of the battery trying to power four motors of it only needed to power three. So a voltage spike happened.

Sent from my HTC6535LVW using PhantomPilots mobile app

So if an ESC failed (essentially burned open, and quit drawing current from the battery), the load on the battery would basically be decreased. When the load on a battery decreases, the voltage will go up. So I think this was an ESC failure.