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Small crashed had motors smoking badly, stink badly but still work
1056 9 2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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Hi all, I had a horrible event recently with my Phantom 3 Adv. It was a nice day in the north east so i took it out to do a ltitle flying and I accidently backed in to a small branch (was hard to see with no leaves) The prop broke right away, it hit another branch, I throttled down as it was falling and it hit the deck on the wal down but before it even hit the ground I was sending the motor shut off command. On its way down it was making a horrible shrieking noise (high pitched) and when it hit the ground it landed upside down and the motors continued to make the shrieking noise. It would not accept the shut down command, tons of errors were coming up on the ipad. As I was taking out the battery to get it to stop, 2 or 3 of the motors started smoking bad.

I have flown home made quads and never quite seen something like this, not sure what exactly happened. First anyone any ideas what happened? I would say maybe from being upside down the motors were stuck and trying to go full throttle (but why did it not accept the shutdown command?) I also thought the phantom had "smart esc" that detect stuck motors and have them safe shutdown?

The motors smoked for a while (i thought the plastic was going to catch on fire for sure but it didnt). They were burning hot for like 30 minutes even though i left it in the cold outside.


The craziest part is today I wanted to evaluate how bad the drone is, if I need just motors or also speed controller board.  To my amazement all 4 motors worker properly in a test without a prop.  They spin at normal speed and seem fine.  2 of the motors still stink badly like burnt electronics though.


I am trying to understand why this happened, why the motors didnt stop when the drone detected they were blocked, why the drone didnt respond to the shutdown stick commands (it was clearly still connected as i could see the picture on the tablet and errors were coming up like crazy).  I am thinking I should replace all 4 motors regardless as they are clearly damaged even if they still work for the moment.  I wouldnt want to lose a motor or two in a flight and lose the drone all together.  


Thanks



2017-1-11
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Steve-76
Second Officer

United States
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replace  them! The motor windings have a coating over the wire to prevent it from shorting out once it gets overheated and starts to melt which is the smell and smoke even if it works it could take nothing to seize up the motor and dropped from the sky and you never know when it could happen

Think of having a live electrical wire in a puddle next to your feet and all it takes is a little bit of the water to drift before you're shocked
2017-1-11
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Steve-76
Second Officer

United States
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I've had other quadcopters in the motor hit the grass blade hit the grass rather quickly but it was enough to smoke the motor then it took out the ESC
2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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Steve-76 Posted at 2017-1-11 07:05
replace  them! The motor windings have a coating over the wire to prevent it from shorting out once it gets overheated and starts to melt which is the smell and smoke even if it works it could take nothing to seize up the motor and dropped from the sky and you never know when it could happen

Think of having a live electrical wire in a puddle next to your feet and all it takes is a little bit of the water to drift before you're shocked

I already ordered replacement motors.  What about the ESC's?  Should I be concerned?
2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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Steve-76 Posted at 2017-1-11 07:07
I've had other quadcopters in the motor hit the grass blade hit the grass rather quickly but it was enough to smoke the motor then it took out the ESC

Yeah I just dont understand why it wouldnt respond to the CSC (kill command)
2017-1-11
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endotherm
Captain
Flight distance : 503113 ft

Australia
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fanseaea4b06 Posted at 2017-1-11 08:43
Yeah I just dont understand why it wouldnt respond to the CSC (kill command)

There have been a couple of similar cases discussed on the forum recently.  In a nutshell, if the aircraft is upside down, it will spin up the two lowest motors into overdrive and try its hardest to right itself.  This move seems to have priority over everything else, you can't kill the motors while it is upside down or steer it etc.  This is probably a safety feature.    Once it has righted itself you get control back.  Unfortunately if it crashes and lands on its top, the aircraft doesn't know it is on the ground and thinks it is still flying.  The motors spin up in a vain attempt to right itself, which unfortunately gets the motors very hot, and starts to melt the lacquer on the copper motor windings.  As long as it doesn't burn off completely, the motors will still work, but they are weakened and damaged and should be replaced.  They are comparatively inexpensive.  If the motors still seem to work correctly and flight is still possible, the ESC should still be OK, they are more of a go/no-go deal.  Hopefully the arms haven't melted too much and distorted.  Be aware the motors are naturally canted and are not straight up and down, so you might get the impression they have melted and  are leaning over, this isn't the case.
2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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endotherm Posted at 2017-1-11 11:05
There have been a couple of similar cases discussed on the forum recently.  In a nutshell, if the aircraft is upside down, it will spin up the two lowest motors into overdrive and try its hardest to right itself.  This move seems to have priority over everything else, you can't kill the motors while it is upside down or steer it etc.  This is probably a safety feature.    Once it has righted itself you get control back.  Unfortunately if it crashes and lands on its top, the aircraft doesn't know it is on the ground and thinks it is still flying.  The motors spin up in a vain attempt to right itself, which unfortunately gets the motors very hot, and starts to melt the lacquer on the copper motor windings.  As long as it doesn't burn off completely, the motors will still work, but they are weakened and damaged and should be replaced.  They are comparatively inexpensive.  If the motors still seem to work correctly and flight is still possible, the ESC should still be OK, they are more of a go/no-go deal.  Hopefully the arms haven't melted too much and distorted.  Be aware the motors are naturally canted and are not straight up and down, so you might get the impression they have melted and  are leaning over, this isn't the case.

Thanks this makes a lot of sense.  Especially because I believe its 2 motors next to each other which are the ones that burned up, so it must have been those 2 trying to flip the drone over.  I am going to replace all 4 motors anyways to be on the safe side since they are cheap.
2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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fanseaea4b06 Posted at 2017-1-11 11:14
Thanks this makes a lot of sense.  Especially because I believe its 2 motors next to each other which are the ones that burned up, so it must have been those 2 trying to flip the drone over.  I am going to replace all 4 motors anyways to be on the safe side since they are cheap.

Regaring replacing the motors, I have watched some videos about taking apart the drone, however I am reading there is some kind of glue over the solder points?  What would be the best way to remove this?  With a knife a pick it off or burn it away with the soldering iron?
2017-1-11
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endotherm
Captain
Flight distance : 503113 ft

Australia
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fanseaea4b06 Posted at 2017-1-11 15:32
Regaring replacing the motors, I have watched some videos about taking apart the drone, however I am reading there is some kind of glue over the solder points?  What would be the best way to remove this?  With a knife a pick it off or burn it away with the soldering iron?

It is probably silicone caulk.  Picking away at it is probably the best way to remove it.
2017-1-11
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fanseaea4b06
lvl.2
Flight distance : 276986 ft
United States
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Unfortunately I didnt know  DJI changed the motors on these Phantom 3's.  My research said I needed part 7 and part 8, I ordered 2 of each and they arent the same as the motors I have.  It looks like i have the A models of the motors.  I dont get why DJI didnt change the part numbers?????  They are both part 7 and 8 even though they arent compatible?

Now I gotta try and return the motors I bought and get the correct ones.
2017-1-15
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