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RC lost signal - crash in the mud

BeyonTV

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Hi there – I'm new here in hopes someone can help me. First of: I do not have DJI Care Refresh, I didn't know that this even existed before this happened.

An hour ago or so, my RC suddenly lost the signal to the drone while in ActiveTrack. First the image signal went down, then the whole RC signal. Managed to activate RTH before the whole signal dropped, but the drone never returned. Half an hour later I find the drone around the last GPS location in the mud. Everything is covered. I don't know why this happened, it was about 40 meters high and couldn't have crashed into anything. I'm seriously pissed at this drone right now to be honest.

However: As I said, everything is covered in mud. No other optical damage, the props are fine, the battery works. I didn't dare to turn this thing on yet.
So - what the heck do I do now? Clean it? How? The mud even got into the air intakes and everything. Some of the props are hard to spin. Where do I start?
 
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Post some pics please
 
Before you start taking things apart, you might consider filing a warranty claim with DJI if it's less than a year old. Mavic and mud dont mix, and you will have to strip the whole Mavic down which could take hours. Since it was apparently not your fault, you should try DJI.
 
Post some pics please
Imgur: The magic of the Internet
Here's a flight log by the way - the drone just straight turned off mid-air: DJI Flight Log Viewer - PhantomHelp.com

I do fear though that the warranty claim wouldn't be valid as there are power lines nearby where I started (I was aware of them though, therefore I always avoided them by several meters). But guess I'll try contacting support tomorrow.

edit: Just dared to try to turn it on. No life signal from the Mavic. The battery turns on, but the Mavic itself does nothing. In that case I'll actually try contacting support tomorrow in hope that the support is better than the experiences many of my friends had.
 
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Hi there – I'm new here in hopes someone can help me. First of: I do not have DJI Care Refresh, I didn't know that this even existed before this happened.

An hour ago or so, my RC suddenly lost the signal to the drone while in ActiveTrack. First the image signal went down, then the whole RC signal. Managed to activate RTH before the whole signal dropped, but the drone never returned. Half an hour later I find the drone around the last GPS location in the mud. Everything is covered. I don't know why this happened, it was about 40 meters high and couldn't have crashed into anything. I'm seriously pissed at this drone right now to be honest.

However: As I said, everything is covered in mud. No other optical damage, the props are fine, the battery works. I didn't dare to turn this thing on yet.
So - what the heck do I do now? Clean it? How? The mud even got into the air intakes and everything. Some of the props are hard to spin. Where do I start?
 
Hi there – I'm new here in hopes someone can help me. First of: I do not have DJI Care Refresh, I didn't know that this even existed before this happened.

An hour ago or so, my RC suddenly lost the signal to the drone while in ActiveTrack. First the image signal went down, then the whole RC signal. Managed to activate RTH before the whole signal dropped, but the drone never returned. Half an hour later I find the drone around the last GPS location in the mud. Everything is covered. I don't know why this happened, it was about 40 meters high and couldn't have crashed into anything. I'm seriously pissed at this drone right now to be honest.

However: As I said, everything is covered in mud. No other optical damage, the props are fine, the battery works. I didn't dare to turn this thing on yet.
So - what the heck do I do now? Clean it? How? The mud even got into the air intakes and everything. Some of the props are hard to spin. Where do I start?
 
Sounds like a nasty landing for sure. I’m with Thunderdrones, see if warranty. They can check the black box for equipment malfunctions.

If they do give you a new drone, opt for the refresh express... well worth the peace of mind; I’ve used it twice and it worked like a charm. I received brand new birds, not refirbished.

If the warranty doesn’t work out, then try flushing everything with electrical contact cleaner (warning very flammable) but first, check it on a small area to ensure it doesn’t melt any components or resolve the paint. It’s usually safe but never hurts to make sure.

Try to prevent the blades from turning while cleaning, as the sand content in the mud is harder than any metal; thus can and will cut into the precision components of the motors.

Flushing can be a waste of time if yo have fried circuitry but the cleaner is cheap. You can pick it up at most auto parts stores.

Once sufficiently flushed, you’ll want to use compressed air to remove any lodged grit but be aware of things like shaft seals. Blowing directly into them can introduce foreign objects into the clean environment inside the motor. Only use compressed air when absolutely necessary.

The bottom of the drone will most likely need to be removed before cleaning can begin. There are sensors in the bottom along with cooling fans, that may have sucked in some moisture. Removing the bottom will give you assurance it’s clean and dry before introducing power.

Once all the motors have been flushed, check each one to ensure that they turn freely and no resistance is felt. This will require that you turn very slowly in both directions, feeling for the slightest resistance. You should only feel the slight jerking of the brushless motor magnets.

Once clear, see that all four blades spin the equal amount of turns under the same applied force. For example, close the blades together. Holding the drone nose up with blades facing you, turn the blades to the 12:00 position. Then gently move then clockwise until they fall under their own weight. Unobstructed, they should rest at about the 7:00 position.

I hope this helps some. I’ve ripped off my camera and broken off the front legs, and it keeps on flying. Your main concern is moisture and grit (fine sand particles). If you take your time, you can be up and flying again.
 
It appears that you were flying at around 30 m AGL at the point of disconnect, and that the disconnect location coincided precisely with one of two large sets of transmission lines crossing the flight path. Are you quite sure the aircraft didn't simply collide with them?

screenshot89.jpg
 
It appears that you were flying at around 30 m AGL at the point of disconnect, and that the disconnect location coincided precisely with one of two large sets of transmission lines crossing the flight path. Are you quite sure the aircraft didn't simply collide with them?

View attachment 29124
I managed to recover the video from the SD card (which was corrupt) up to the spot where it turned off.
Seems like I actually did get quite near to the power lines, but did not crash into them. If I had to guess, I'd say about 6-8 inches away from them. The video then suddenly stops.
Could it be that the electrical field around there fried something? I could understand if the RC signal simply went down and the drone went into ATTI mode or something because of the power lines, but an instant shutdown and crash?
 
I managed to recover the video from the SD card (which was corrupt) up to the spot where it turned off.
Seems like I actually did get quite near to the power lines, but did not crash into them. If I had to guess, I'd say about 6-8 inches away from them. The video then suddenly stops.
Could it be that the electrical field around there fried something? I could understand if the RC signal simply went down and the drone went into ATTI mode or something because of the power lines, but an instant shutdown and crash?

The video file is saved to the card with a slight delay, so if a collision kills the power to the aircraft then the actual collision is typically not recorded. That's one possibility. The other is that if the aircraft was very close to one of the lines then possibly the local electric field (∝1/d²) was strong enough to induce fatal effects in the aircraft electronics.

In any case, it looks highly likely that the cause was either hitting or coming too close to a high-voltage conductor, and so I think you are going to have an uphill battle getting DJI to accept this as a warranty issue. They are going to tell you it was pilot error.
 
The video file is saved to the card with a slight delay, so if a collision kills the power to the aircraft then the actual collision is typically not recorded. That's one possibility. The other is that if the aircraft was very close to one of the lines then possibly the local electric field (∝1/d²) was strong enough to induce fatal effects in the aircraft electronics.

In any case, it looks highly likely that the cause was either hitting or coming too close to a high-voltage conductor, and so I think you are going to have an uphill battle getting DJI to accept this as a warranty issue. They are going to tell you it was pilot error.
By '6-8 inches away from them' I meant 6-8 inches away upwards. So the power lines were some inches below me. As seen in the flight log, the drone did not descend in its last seconds but kept its height, so I guess I can exclude the possibility of an actual collision. If anything, the electrical field burned it.
So I guess I'll have no luck with the warranty case but can throw that thing away basically.
 
By '6-8 inches away from them' I meant 6-8 inches away upwards. So the power lines were some inches below me. As seen in the flight log, the drone did not descend in its last seconds but kept its height, so I guess I can exclude the possibility of an actual collision. If anything, the electrical field burned it.
So I guess I'll have no luck with the warranty case but can throw that thing away basically.

There is nothing to lose in submitting the case to DJI - they sometimes surprise with what they are willing to cover. They might at least offer a discount. But in the end you may have to chalk this up to a lesson in flight planning.
 
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Hi there – I'm new here in hopes someone can help me. First of: I do not have DJI Care Refresh, I didn't know that this even existed before this happened.

An hour ago or so, my RC suddenly lost the signal to the drone while in ActiveTrack. First the image signal went down, then the whole RC signal. Managed to activate RTH before the whole signal dropped, but the drone never returned. Half an hour later I find the drone around the last GPS location in the mud. Everything is covered. I don't know why this happened, it was about 40 meters high and couldn't have crashed into anything. I'm seriously pissed at this drone right now to be honest.

However: As I said, everything is covered in mud. No other optical damage, the props are fine, the battery works. I didn't dare to turn this thing on yet.
So - what the heck do I do now? Clean it? How? The mud even got into the air intakes and everything. Some of the props are hard to spin. Where do I start?

hmm active track at. 30m so presumably it was following whilst you were on a bike? So you didn’t see it hit anything and would not have even thought about RTH before it hit the deck! Is that right?

Deffo looks like the power lines were contributing due to pilot error!
 
hmm active track at. 30m so presumably it was following whilst you were on a bike? So you didn’t see it hit anything and would not have even thought about RTH before it hit the deck! Is that right?

Deffo looks like the power lines were contributing due to pilot error!
Nope, was following the car of my friend. Had my eyes on the display the whole time and regularly checked it in direct view. Once the image signal went down, immediately hit RTH as I always do in such cases. No luck.
And as the aircraft fails to turn on now, I suppose that the board actually was fried and it never received the RTH command as it was already dead.
 
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Btw how do you know it cleared the power lines by 6-8 inches?
 
Btw how do you know it cleared the power lines by 6-8 inches?
Because I repaired the video file and can clearly see it flew several inches above them. The video stops at the very last of the four power lines, so the other three were no problem, too. If it was at the same height as the power lines, it would have crashed at the first one already.
The aircraft therefore was above the power lines and the only real solution to this is that it was fried.

DJI 0001 - Youtube On Repeat
If you switch to 4K, you should see the power lines under the Mavic and that the last one is under the aircrafts height, too.
 
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Because I repaired the video file and can clearly see it flew several inches above them. The video stops at the very last of the four power lines, so the other three were no problem, too. If it was at the same height as the power lines, it would have crashed at the first one already.
The aircraft therefore was above the power lines and the only real solution to this is that it was fried.

DJI 0001 - Youtube On Repeat
If you switch to 4K, you should see the power lines under the Mavic and that the last one is under the aircrafts height, too.

Two comments. Firstly - that transmission set has at least 7 lines, not 4. Secondly, the gimbal was angled down so you would not have seen a line at the same height as the aircraft.
 
Two comments. Firstly - that transmission set has at least 7 lines, not 4. Secondly, the gimbal was angled down so you would not have seen a line at the same height as the aircraft.
True for the first one, I guessed the number while writing that comment tbh.
For the second one, I did saw all of the other power lines in the video though, so I know for a fact that the one seen in the video is the very last one.

Not complaining at all, in the end it was my fault, just wanted to note that it definitely wasn't a direct collision.
 
On those tower lines there is an earth wire above the conductors, this protects against lightning, you may have clipped the earth wire.
 
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True for the first one, I guessed the number while writing that comment tbh.
For the second one, I did saw all of the other power lines in the video though, so I know for a fact that the one seen in the video is the very last one.

Not complaining at all, in the end it was my fault, just wanted to note that it definitely wasn't a direct collision.

Are you quite sure that you saw all the lines? The reason for wanting to pin this down definitively is that it would be the first case that I've seen where the alternating electric field from a transmission line took out the aircraft electronics. Theoretically it doesn't surprise me, but it would be nice to know for certain.
 
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