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Camera lens cracked as a result of mist/fog causing infrared sensor failure

ChristoffB

Well-Known Member
Join
Jan 14, 2019
Messages
64
Age
36
Loc
South Africa
Good day all,

So yesterday the unfortunate happened...

I was flying on a mountain pass, taking photos of the mist as it was coming in from the ocean. I was caught off guard a bit by die speed in which the mist suddenly descended on me. Knowing that mist/fog and the spark don't mix, I immediately started to decent in order to land. On the way I got the message "Infra red sensors failure, land as immediately". I continued to throttle down. Drone went into RTH, so I let it do it's thing. Then I noticed that it is coming in a bit hot, so I hit the pause button - no reaction. Came in hot, clipped the fence by the side of the road and fell to the ground. Results were some damaged props, but worst of all -a cracked camera lens.

Now I have 3 questions -
- Was this normal behavior of the spark? I must add that as the drone descended it had cleared the mist/fog completely (at least by 20m height) before hitting the ground.
- Will a repair center be able to replace the lens, or does the whole gimbal need replacing?
- Can this be a warranty claim?

Flight record here:
here
 
Last edited:
Good day all,

So yesterday the unfortunate happened...

I was flying on a mountain pass, taking photos of the mist as it was coming in from the ocean. I was caught off guard a bit by die speed in which the mist suddenly descended on me. Knowing that mist/fog and the spark don't mix, I immediately started to decent in order to land. On the way I got the message "Infra red sensors failure, land as immediately". I continued to throttle down. Drone went into RTH, so I let it do it's thing. Then I noticed that it is coming in a bit hot, so I hit the pause button - no reaction. Came in hot, clipped the fence by the side of the road and fell to the ground. Results were some damaged props, but worst of all -a cracked camera lens.

Now I have 3 questions -
- Was this normal behavior of the spark? I must add that as the drone descended it had cleared the mist/fog completely (at least by 20m height) before hitting the ground.
- Will a repair center be able to replace the lens, or does the whole gimbal need replacing?
- Can this be a warranty claim?

Flight record here:
here

Saw your flight record. The drone never went into RTH mode. It went into landing mode once the infra-red sensors failed. That's why the pause button didn't work for you. You must have had very little time to react but in hindsight you should have used the right stick to maneuver the drone and prevent it from hitting the fence while it was still coming down. Now whether the mist/fog caused the infra-red sensors to fail is something I guess only DJI will be able to tell. The DJI website lists the price of different components related to camera and gimbal. So if it is just a lens crack, I don't think the whole unit needs to be replaced. You can check the link below.

 

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Saw your flight record. The drone never went into RTH mode. It went into landing mode once the infra-red sensors failed. That's why the pause button didn't work for you. You must have had very little time to react but in hindsight you should have used the right stick to maneuver the drone and prevent it from hitting the fence while it was still coming down. Now whether the mist/fog caused the infra-red sensors to fail is something I guess only DJI will be able to tell. The DJI website lists the price of different components related to camera and gimbal. So if it is just a lens crack, I don't think the whole unit needs to be replaced. You can check the link below.

Thank you for the reply.

You are quite correct - Spark went into landing mode and not RTH as I've stated. Because of it coming down so fast by the time I saw that it will hit the fence it was too late... Why did it descent at such a fast rate? Even without hitting the fence I am almost certain there would have been damage as a result of it hitting the gravel surface. I would have thought that the infrared sensors would start working again once it was able to 'see' the ground below.

I have spoken to a authorized repair company and they indicated that one can replace just the cover.

Whatever the outcome is, I am quite sadden by the whole event.
 
Thank you for the reply.

You are quite correct - Spark went into landing mode and not RTH as I've stated. Because of it coming down so fast by the time I saw that it will hit the fence it was too late... Why did it descent at such a fast rate? Even without hitting the fence I am almost certain there would have been damage as a result of it hitting the gravel surface. I would have thought that the infrared sensors would start working again once it was able to 'see' the ground below.

Well I am no expert to tell you for sure what really happened but it seems since the bottom sensors failed, you didn't get the landing protection or cushioning effect when the drone was coming down. Btw, when I checked your flight record in phantom log viewer, I saw that the increase in speed was only after 3:14.5 and from the attitude indicator it looks like the drone had hit something at that point.

Flight.JPG
 
Well I am no expert to tell you for sure what really happened but it seems since the bottom sensors failed, you didn't get the landing protection or cushioning effect when the drone was coming down. Btw, when I checked your flight record in phantom log viewer, I saw that the increase in speed was only after 3:14.5 and from the attitude indicator it looks like the drone had hit something at that point.

View attachment 9752
Thank you for the link to the Phantom log viewer. I can assure you the only thing it hit was the fence which is probably about 1.2m high of the ground. So it actually increased it's "forced landing" descending speed from 0.2mph to +-3/4mph before hitting the fence. Surely this can't be normal? What is the fastest the spark can even descend?

Is it worth trying to log a ticket at DJI? I am based in South Africa where we don't even have an official DJI service center, only "recommended service centers".

I get that by me flying the drone in mist/fog it is user error, but the acceleration in descending speed does not seem right to me. I am worried that the impact might have caused damage that I cannot see on the outside. Test flights seemed to be OK, even gimbal is operating as expected. Should I be worried?
 
Thank you for the link to the Phantom log viewer. I can assure you the only thing it hit was the fence which is probably about 1.2m high of the ground. So it actually increased it's "forced landing" descending speed from 0.2mph to +-3/4mph before hitting the fence. Surely this can't be normal? What is the fastest the spark can even descend?

Is it worth trying to log a ticket at DJI? I am based in South Africa where we don't even have an official DJI service center, only "recommended service centers".

I get that by me flying the drone in mist/fog it is user error, but the acceleration in descending speed does not seem right to me. I am worried that the impact might have caused damage that I cannot see on the outside. Test flights seemed to be OK, even gimbal is operating as expected. Should I be worried?

OK. That doesn't explain the abrupt change in AC attitude but if you see the screenshot I had shared above, before 3:14.5, the VPS sensors are detecting something below, hence the speed is less. Beyond 3:14.5, they detect nothing and your AC's speed start increasing. The manual states that max. descent speed is 3m/s (~11km/hr) while auto landing, which your Spark was doing. The only way to get cushioning or reduced speed while the Spark is auto-landing is by having fully functional bottom sensors, which obviously wasn't true in your case. So what you saw as fast rate of descent was the AC's normal rate of descent when the bottom sensors don't detect any obstacle below. Regarding your question about internal damage, even DJI would ask you to send the drone to them if they have to ascertain if there are any. I think you should get the bottom sensor checked if you do not want similar incidents in the future.

spec.JPG
 
OK. That doesn't explain the abrupt change in AC attitude but if you see the screenshot I had shared above, before 3:14.5, the VPS sensors are detecting something below, hence the speed is less. Beyond 3:14.5, they detect nothing and your AC's speed start increasing. The manual states that max. descent speed is 3m/s (~11km/hr) while auto landing, which your Spark was doing. The only way to get cushioning or reduced speed while the Spark is auto-landing is by having fully functional bottom sensors, which obviously wasn't true in your case. So what you saw as fast rate of descent was the AC's normal rate of descent when the bottom sensors don't detect any obstacle below. Regarding your question about internal damage, even DJI would ask you to send the drone to them if they have to ascertain if there are any. I think you should get the bottom sensor checked if you do not want similar incidents in the future.

View attachment 9754
Thank you for taking the time to analyze my incident, I really appreciate it! My theory would then be that the moisture content of the fog/mist resulted in some condensation on the bottom sensors which resulted in the error not being cleared as it closed in on the ground.

I think the fence (it was a wire fence) actually cushioned the impact. The cracked lens was probably because of the spark falling face down on some sharp chip-stone. The aircraft flipped over and in the process scuffed the propellers as it rotated on the gravel until the aircraft shut off. There are literally no other signs of impact on the rest of the drone.

A very expensive lesson learned nevertheless... ?
 
Thank you for taking the time to analyze my incident, I really appreciate it! My theory would then be that the moisture content of the fog/mist resulted in some condensation on the bottom sensors which resulted in the error not being cleared as it closed in on the ground.

I think the fence (it was a wire fence) actually cushioned the impact. The cracked lens was probably because of the spark falling face down on some sharp chip-stone. The aircraft flipped over and in the process scuffed the propellers as it rotated on the gravel until the aircraft shut off. There are literally no other signs of impact on the rest of the drone.

A very expensive lesson learned nevertheless... ?

Everyone in this forum should rather thank you for documenting the incident in so much detail here. It is a good lesson to learn for all - never fly in the fog. I can only hope that there was no serious internal damage due to the crash and repairs won't burn a big hole in your pocket. Good luck.
 

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