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Death Spiral
2115 27 2017-12-15
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fans4a4d3789
lvl.4
United States
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Hello fellow pilots.
I search through these forums on a regular basis in order to find posts similar to my experience today, so I thought I would share.

I just had an Inspire 1 pro, approximately 1 and a half years old with a little over 100 flights, fall out of the sky today as I was slowly raising the altitude. I am still unsure of exactly what happened but I have a couple thoughts on it. I am very careful about my pre-flight checks and everything was properly attached and the arms did not have any cause for concern.

Facts of the flight:
- Battery was initially at 97% on take-off, due to heating the battery prior to flight.
- Received a "Battery temperature is below 15 degrees celsius, Warm up the battery to above 25 degrees Celsius"
- Received a "Propulsion output is limited due to battery health"
- Saw the initial voltage drop to approximately 3.3V immediately after take-off
- The camera was still working and displaying as it was falling (Don't believe it was a battery issue)
- The aircraft yawed clockwise during fall

Inspection of the crashed drone:
- Right front motor was partially seized. It would still rotate, but was difficult to get it to turn. All other motors were properly rotating
- All quick-release propellar locks were in locked position at the time of inspecting the UAV.

I have a feeling that the right front motor may have seized during the flight, which caused the drone to fall. This motor partially being seized seems unlikely to be damage related due to no direct contact at the motor. There was, however, direct contact damage on that same motors landing gear, directly below the partially seized motor. The damage on this landing gear appears to be consistent with taking most of the impact with asphault. This also makes me think that a seized motor would induce a roll such that it would be the first contact point with the ground.

I will post updates on what DJI's analysis reveals.


2017-12-15
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Grumpysrb
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Flight distance : 11004 ft
United States
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I had a similar incident with my P3s a week ago.  I’m not sure but think it was a battery issue.  
2017-12-15
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DJI Mindy
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Hello Sir, we are sorry to read on the crash accident, let's wait for the result of data analysis, our team will try their best to find out the reason, if you need any assistance, please post the case number here, thank you.
2017-12-16
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DJI Mindy
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Grumpysrb Posted at 2017-12-15 20:12
I had a similar incident with my P3s a week ago.  I’m not sure but think it was a battery issue.

Grumpysrb, sorry for the accident, did you send in the drone for data analysis and repair service? Our repair team will help to take care of your drone.
2017-12-16
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Mark Guille
Captain
Flight distance : 2031818 ft
Jersey
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I'm sorry to hear about your unfortunate incident.

How long before this flight had the battery been charged?
Do you recall the air temperature that day?
How did you heat up the battery?
How long after takeoff did you get the warnings:-
     
    -Battery Temp is below 15 degrees?
    -Propulsion output is limited?

How long after takeoff did the voltage drop to 3.3V?
Which mobile device were you using?

Mark G.
2017-12-17
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Mrothart
lvl.4
United States
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Mark Guille Posted at 2017-12-17 01:47
I'm sorry to hear about your unfortunate incident.

How long before this flight had the battery been charged?


-I always charge my TB48 battery just prior to flight. So approximately 1 hour prior to flight.

-The air temperature at the time was approximately 60 degrees.

-I used the battery warmer that came with the Inspire 1 Pro package along with sitting it at the car heater for a while.

The warnings came just after taking off. Also, the battery voltage showed a normal voltage (approximately 4V, it was green) and then changed to red shortly after takeoff.

We just got the new ultra bright crystalsky
2017-12-17
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Mrothart
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Mark Guille Posted at 2017-12-17 01:47
I'm sorry to hear about your unfortunate incident.

How long before this flight had the battery been charged?


-I always charge my TB48 battery just prior to flight. So approximately 1 hour prior to flight.

-The air temperature at the time was approximately 60 degrees.

-I used the battery warmer that came with the Inspire 1 Pro package along with sitting it at the car heater for a while.

The warnings came just after taking off. Also, the battery voltage showed a normal voltage (approximately 4V, it was green) and then changed to red shortly after takeoff.

We just got the new ultra bright crystalsky
2017-12-17
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Mrothart
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United States
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Just an update. I received an email with a quote from DJI.

Dear Customer, Unfortunately, damage that is not caused by a product malfunction or is out of the warranty period is not covered by DJI aftersales policy. Your unit is out of its 1 year warranty coverage period We will either repair it or replace it with a product that's new or equivalent to new in both performance and reliability after payment has been received. For more information, please visit http://www.dji.com/service/policy DJI North America

I was told that they are unwilling to investigate the cause of this accident due to it being out of the 12 month warranty period.

So, "damage not caused by a product malfunction or out of the warranty period is not covered by DJI". That make sense to me. However, what does not make sense is how is "product malfunction" determined if they are unwilling to investigate a crash that has occurred outside of the 12 month period?

I find this response completely unacceptable. This type of issue makes me lose my trust in DJI as a company and in their products. How can I be willing to purchase another $10,000 drone that may just fall out of the sky at any moment? I  want to know exactly what caused this drone to fall from the sky.

Moderators, my case number is CAS-1310797-H5P1Q6. I really hope some further investigation can be done.
2017-12-19
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RichJ53
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Mrothart Posted at 2017-12-19 15:27
Just an update. I received an email with a quote from DJI.

Dear Customer, Unfortunately, damage that is not caused by a product malfunction or is out of the warranty period is not covered by DJI aftersales policy. Your unit is out of its 1 year warranty coverage period We will either repair it or replace it with a product that's new or equivalent to new in both performance and reliability after payment has been received. For more information, please visit http://www.dji.com/service/policy DJI North America


Sorry for your loss and report of the DJI summary. In your first post you stated it was one and half years old which would tell us it was out of warranty. It really sounds like a bad battery based on your post to Mark to me. The fact that the battery voltage dropped so soon after take off would indicate something wrong with the power IMO.... 60*F is not really that cold either. But  the seized up motor could have been caused by the crash  and it is always really hard to say based on your description...  How many charge cycles did you have on this TB 47 battery? even my battery at 68 cycles show 100% when charged up all the way up, but the capacity is only about 4010 mAh

Lots of parts that can potentially fail in these aircraft at anytime. really sorry for your loss

Rich
2017-12-19
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Mrothart
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RichJ53 Posted at 2017-12-19 16:08
Sorry for your loss and report of the DJI summary. In your first post you stated it was one and half years old which would tell us it was out of warranty. It really sounds like a bad battery based on your post to Mark to me. The fact that the battery voltage dropped so soon after take off would indicate something wrong with the power IMO.... 60*F is not really that cold either. But  the seized up motor could have been caused by the crash  and it is always really hard to say based on your description...  How many charge cycles did you have on this TB 47 battery? even my battery at 68 cycles show 100% when charged up all the way up, but the capacity is only about 4010 mAh

Lots of parts that can potentially fail in these aircraft at anytime. really sorry for your loss

I had ~30 cycles on that battery. Probably a little less than that. I was watching the voltage, it initially dropped to that low voltage, then rose back to around 3.5 V after 20 seconds. I was watching the voltage as I was raising the altitude. It initially seemed to be a battery issue to me as well, but it seems to make more sense to me that more than the one motor would have turned off with a low voltage and that the camera would not be transmitting a signal either.

Just my thoughts. Appreciate the responses.
2017-12-19
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RichJ53
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Mrothart Posted at 2017-12-19 16:18
I had ~30 cycles on that battery. Probably a little less than that. I was watching the voltage, it initially dropped to that low voltage, then rose back to around 3.5 V after 20 seconds. I was watching the voltage as I was raising the altitude. It initially seemed to be a battery issue to me as well, but it seems to make more sense to me that more than the one motor would have turned off with a low voltage and that the camera would not be transmitting a signal either.

Just my thoughts. Appreciate the responses.


Appreciate your thoughts and additional information. 30 cycles is not many, but I had a problem with a TB 47 battery that only had had 1 cycle on it.  I guess anything is possible, but I am more incline to think something in your battery was not up to par. With less than  minutes of flight time the battery voltage should not have dropped below 4 volts per cell (IMO). Again we could speculate all day about what it might be.... maybe your Blackbox records would tell the rest of the story. To bad we will not know.

All the best and please keep us posted if you are able to get DJI to investigate this further.
Rich
2017-12-19
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Mrothart
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I am looking forward to hearing back from a moderator in order to see what can be done about a data analysis.
2017-12-20
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Mark Guille
Captain
Flight distance : 2031818 ft
Jersey
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Mrothart Posted at 2017-12-20 09:59
I am looking forward to hearing back from a moderator in order to see what can be done about a data analysis.

Is there any chance of you sharing the data for that flight here?

Mark G.
2017-12-20
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Mrothart
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United States
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I was unable to recover the .DAT files. All I have is the flight log via the DJI GO app.

I have paid the bill for the drone and am hoping they repair do not replace it so I can recover the .DAT files.
2017-12-20
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RJ934
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Sorry for your problems! I have lost all confidence in DJI due to their continuous software issues. With that said, sixty degrees is not really cold so that should not be the issue. The fact that it was flying and climbing me think that motor failure, while possible, was not the issue. The obvious problem from your discription is the battery. Why did you continue the flight with battery irregularities being reported? The clockwise rotation could be consistent with a right front failure. Did itjust. Drop out of the sky or did it spiral down as if the other motors were trying to spoolup in response resulting in a slower descent than a straight fall? I can understand why they don’t want to dig into it. There is a direct cost to investigate it in man hours and a possibility of liability issues driven by the findings. They have backlogs of repair servicesand the tech time is valuable. Good luch with the replacement but I think the data file is history anyway it goes.
2017-12-21
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Mark Guille
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Mrothart Posted at 2017-12-20 12:35
I was unable to recover the .DAT files. All I have is the flight log via the DJI GO app.

I have paid the bill for the drone and am hoping they repair do not replace it so I can recover the .DAT files.

The data file is normally on your mobile device, I wonder how you get it from your CS?

Mark G.
2017-12-21
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Mrothart
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RJ934 Posted at 2017-12-21 07:26
Sorry for your problems! I have lost all confidence in DJI due to their continuous software issues. With that said, sixty degrees is not really cold so that should not be the issue. The fact that it was flying and climbing me think that motor failure, while possible, was not the issue. The obvious problem from your discription is the battery. Why did you continue the flight with battery irregularities being reported? The clockwise rotation could be consistent with a right front failure. Did itjust. Drop out of the sky or did it spiral down as if the other motors were trying to spoolup in response resulting in a slower descent than a straight fall? I can understand why they don’t want to dig into it. There is a direct cost to investigate it in man hours and a possibility of liability issues driven by the findings. They have backlogs of repair servicesand the tech time is valuable. Good luch with the replacement but I think the data file is history anyway it goes.

Appreciate all the responses. The aircraft spiraled down and did not just drop. I could also hear the aircraft motors still trying to respond. The aircraft also traveled a good distance ( I think around 70 feet) horizontally. According to the log, the aircraft crashed at around 51 mph from a height of 180 feet. This also would be an indication that the aircraft was still causing some lift, as 73 mph (assuming no drag) would be an expected speed from that height.

As for the voltage, it didn't appear to be an immediate concern after the voltage has gone back up after a few seconds and I proceeded to increase the altitude.
2017-12-21
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Mrothart
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Mark Guille Posted at 2017-12-21 08:10
The data file is normally on your mobile device, I wonder how you get it from your CS?

Mark G.

I will look into a way to retrieve the flight log.
2017-12-21
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Mark Guille
Captain
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Mrothart Posted at 2017-12-21 08:43
I will look into a way to retrieve the flight log.

Cool, I really would like to get to the bottom of this.
2017-12-21
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Mrothart
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Found it.
Hopefully this works.

http://app.airdata.com/main?flig ... &amptype=minmax
2017-12-21
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Mike9129
First Officer
Flight distance : 4112812 ft
Ireland
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would i be right in saying you gave it full throttle upwards as soon as you took off?
2017-12-21
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Mrothart
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No. I never like to give it full throttle. I did give it ~60-65% throttle for for the first 10 seconds and then I dropped to about 30% throttle for the remainder of the flight. This is according to my logs.
2017-12-21
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Grumpysrb
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Flight distance : 11004 ft
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DJI Mindy Posted at 2017-12-16 23:41
Grumpysrb, sorry for the accident, did you send in the drone for data analysis and repair service? Our repair team will help to take care of your drone.

No I haven’t.  I’ve decided to leave flying drones for some time.  This last crash, although not my fault, is my third and most damaging.  The hobby has become too unpredictable and unreliable equipmen5 has made it too risk6 for my wallet.
2017-12-25
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Grumpysrb
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Flight distance : 11004 ft
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I think my problem, and probably yours, is a bad cell in the battery.  My crash happened at the end of the flight while landing. I believe the last cell was bad and had no charge. As the drone used the third and went into using the last cell it died.
2017-12-25
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DJI Mindy
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Grumpysrb Posted at 2017-12-25 01:04
No I haven’t.  I’ve decided to leave flying drones for some time.  This last crash, although not my fault, is my third and most damaging.  The hobby has become too unpredictable and unreliable equipmen5 has made it too risk6 for my wallet.

If the drone is still in warranty period, we still recommend to send it in at your most convenience for data analysis and repair service, if you keep flying, the data may be overwritten and it would be hard to find out the accident reason.
2017-12-25
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Mrothart
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Update-

The "repaired" drone was just received. I had specifically requested that if a refurbished drone was going to be sent, or if the .DAT files were going to be compromised, then I did not want anything done on the drone and to have it returned immediately. They confirmed that none of the damaged parts on the repair list would compromise the files.

The model drone sent out was a T601. I received a model T600. I looked at the serial number sticker to see if it matched what I sent in. Sure enough, it was the same sticker. Still hopeful that the .DAT files would be there, I plug in the aircraft, and they were not there. The only logs recorded are from the test flights.

A further examination of the serial number shows that the sticker was actually removed from the old drone and placed onto this "repaired" drone. I noticed this because I took many photos of my drone before I sent it out, and the sticker was not in the same place. This was also evident because the sticker on the "repaired" drone had been tampered with and it did not stick well to the body.

Is this really the type of business DJI supports? And I still have no idea why our drone decided to fall from the sky. If it was user error, then I'm willing to accept that. I want to know what happened so it does not happen again. This whole experience ruins my faith in this company.
2018-1-4
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Mrothart
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And to add salt to the wound. The sent the X5 back with no lens.
2018-1-4
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DTK
Second Officer
Flight distance : 1943159 ft
Australia
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Mrothart Posted at 2018-1-4 08:53
And to add salt to the wound. The sent the X5 back with not lens.

I am really sorry about hearing your ordeal with DJI. What you have experienced is not new, we have seen here before. The reason why you specifically ask DJI to return it with the original drone shows your knowledge about others experience. A thing that now comes to mind is that DJI is run by Chinese although they have foreigners allover the company organization. We in the civilized western world would never accept their way of logical and customer services. But they do only if they can continue to get away with it. This is only my own view please don't take it as an offence to anyone.
2018-1-4
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