Request for determination from log

[Not A Speck Of Cereal]

Hey all,

I lost my P3P in the sound (salt water) and am now trying to determine what the cause was for insurance purposes.

Here is the link to the log file. Please let me know if you need it in another form. (The text file from my tablet FlightRecords folder is also attached.)

Here's the basics:

• Cloudy but calm and dry day, not too windy, viability good
• Flying over water, no obstacles
• Maintained VLOS (except when glancing down at controller of course), had good signal, strong video feed
• Good props, properly mounted
• I was on my 3rd battery, so it flew a fair amount of time with no problems with props / motor / etc.
• Each flight took off with fully charged battery (as I always do that after years of horror stories on this site and others).

Result: It was suddenly gone, I lost signal, and by the time I looked down at the altitude in DJI GO, it was in the minus.

Given the lack of obstacles and the fact that it took, I'm thinking it was a bird strike. There were plenty of birds around and it's spring (getting near nesting time). I usually do a good job of escaping from an attacking bird (stick up!), the fact that there was a white background (clouds) and the birds are white gulls, there could have been one that I didn't see.

The controller app did have a "motor obstructed" message that stayed on the screen (while the RTH been sadly kept beeping), but not an motor overload or anything like that.

So what do you think? Can I tell the claims adjuster that it was likely a bird strike, or do you see any other possibilities in the logs?

Thanks for any help,
Chris

 

[Fly Dawg]

The controller app did have a "motor obstructed" message that stayed on the screen (while the RTH been sadly kept beeping), but not an motor overload or anything like that.

This could very well have been a bird strike AND a lost prop. It is difficult to differientiate between the two without the aircraft data file. However, I will say that I see no initiation of RTH in the log and the "motor obstructed" warning could be either the strike itself, or a combination of a lost prop from such.

 

[Not A Speck Of Cereal]

Cool. Well, the RTH was probably automatically started from the lost-signal time-out, which could have happened after the craft was below the surface of the water.

The prop possibility: as I said, this was the 3rd flight (changing batteries) without touching the props. To me, it sound unlikely that the props would have worked fine for the first two flights (including ventures out over the puget sound and back again each time), then failed the 3rd time. Note that these are the DJI (not 3rd party) Carbon fiber props, which I pre-balance myself.

Man, that pitch and roll is all over the place in those last few seconds.

Thanks for your time and reply!
Chris

 

[Fly Dawg]

To me, it sound unlikely that the props would have worked fine for the first two flights (including ventures out over the puget sound and back again each time), then failed the 3rd time.

Agreed, to the point there were no drastic measures that I could see in the RC data. My theory is both. Something hit the rear of the aircraft and cause the severe pitch up and then roll over. If this was a bird, you can speculate the bird hit the prop, which in turn unscrewed it from the hub and therefore the relatively immediate decent in to the water.

 

[Not A Speck Of Cereal]

Something hit the rear of the aircraft and cause the severe pitch up and then roll over. If this was a bird, you can speculate the bird hit the prop, which in turn unscrewed it from the hub and therefore the relatively immediate decent in to the water.

That sounds reasonable, thanks.

Chris

 

[WV. Rootman]

Sorry to hear about your loss. Even when you play by all the rules, things will happen. Fortunately prices are lower on P3's. Good luck on getting a new drone. Oh, pity the gull that a carbon prop hits. LOL

 

[With The Birds]

This could very well have been a bird strike AND a lost prop. It is difficult to differientiate between the two without the aircraft data file. However, I will say that I see no initiation of RTH in the log and the "motor obstructed" warning could be either the strike itself, or a combination of a lost prop from such.

View attachment 110676

How could a lost prob be reported as motor obstructed? Obstructed would be lower RPM than commanded with excessive current with lost prop being the opposite....

 

[Not A Speck Of Cereal]

Thanks. I didn't even get that mad, just sort of a "well, it's been a few years and the law of averages finally caught up to me." It really only hurt because I've learned to take such care, but down it goes anyways.

Part of me thought "maybe it's finally time to move on to the P4", but I have all of these batteries and other P3 accessories. I would probably just get another body, even though it's getting to be a pretty old model.

A couple of related questions for someone that doesn't mind helping:

1. Can my current controller work on another craft, so I don't have to buy the entire package (I think there are craft-only purchases available). I think that I can just re-link it, but I've never had to, so my memory is weak on this part.
   
   
2. I love to fly, but my main interest is photography (and it's nice to have an aerial platform): is the P4 camera tons better in quality? I think it's just the same 1" sensor, but it might still be better. I do video as well.

Yeah, I know there's something new on DJIs horizon too, but I can't afford to go there right now.

Thanks,
Chris

 

[With The Birds]

That sounds reasonable, thanks.

Chris

Wouldn’t an obstructed prop cause it to tighten?

 

[With The Birds]

Thanks. I didn't even get that mad, just sort of a "well, it's been a few years and the law of averages finally caught up to me." It really only hurt because I've learned to take such care, but down it goes anyways.

Part of me thought "maybe it's finally time to move on to the P4", but I have all of these batteries and other P3 accessories. I would probably just get another body, even though it's getting to be a pretty old model.

A couple of related questions for someone that doesn't mind helping:

1. Can my current controller work on another craft, so I don't have to buy the entire package (I think there are craft-only purchases available). I think that I can just re-link it, but I've never had to, so my memory is weak on this part.
   
   
2. I love to fly, but my main interest is photography (and it's nice to have an aerial platform): is the P4 camera tons better in quality? I think it's just the same 1" sensor, but it might still be better. I do video as well.

Yeah, I know there's something new on DJIs horizon too, but I can't afford to go there right now.

Thanks,
Chris

You can fly a P4 standard or another P3 advanced or pro with your controller.

The P4 standard has the same image sensor as your P3P had (not 1”).

You will notice a significant image quality improvement if you move to P4 pro or advanced (1” sensor).

While it’s a great idea to go for the same AC to get the most from the accessories the batteries might be getting close to the end of their best performance.

Hopefully the insurance company will cover you for the loss and you can have some choice. How about a Mavic Pro or M2?

 

[Not A Speck Of Cereal]

While it’s a great idea to go for the same AC to get the most from the accessories the batteries might be getting close to the end of their best performance.

That's a good point. I have a lot of hours on this AC. In fact, there are some cracks (remember when these were showing up on older models?) that I've super-glued to keep from growing. I think the P4 had a new shell partly to fix that issue.

The batteries can only be charged so many times as well, so I should go do the battery check procedure mentioned in the manual to what life they have left.

How about a Mavic Pro or M2?

Do they have the newer / larger sensor?

I have to admit that with the P3P, I've had some dark shots (like sunsets or near-night city-scape shots) that were really noisy and required a noise-reduction in post-processing to fix up.

Chris

 

[sar104]

Agreed, to the point there were no drastic measures that I could see in the RC data. My theory is both. Something hit the rear of the aircraft and cause the severe pitch up and then roll over. If this was a bird, you can speculate the bird hit the prop, which in turn unscrewed it from the hub and therefore the relatively immediate decent in to the water.

Why do you think something hit the aircraft? The pitch/roll/yaw response is consistent with failure of the left rear ESC, transferring the CCW angular momentum of the left rear prop to the aircraft.

 

[Fly Dawg]

Why do you think something hit the aircraft?

Primarily going by the OP's description of "Lots of Gulls" in the area and the low altitude just above the water, ( Gulls will swarm just above the water ) and throwing in the "motor obstruction" and "not enough force" flag, along with the sudden pitch change. Yes, it could be an ESC failure, but taking the former in to consideration it seems more likely than an ESC issue.

 

[sar104]

Primarily going by the OP's description of "Lots of Gulls" in the area and the low altitude just above the water, ( Gulls will swarm just above the water ) and throwing in the "motor obstruction" and "not enough force" flag, along with the sudden pitch change. Yes, it could be an ESC failure, but taking the former in to consideration it seems more likely than an ESC issue.

I don't think it was a collision with a bird. The immediate response of the aircraft was the typical ~ 3 Hz spin and tumble. Even if a brief collision occurred (of which there seems to be no indication in the log), the motor would not have remained obstructed. The sudden pitch, roll and yaw excursions look exactly like every other single motor propulsion loss event that I've seen - they do not, themselves, indicate a collision.

 

[Fly Dawg]

Completely agreed that the sudden excursions could very well be an ESC failure. Also looking back at the 2 flags, the "motor obstruction" occurred after the " Not enough force" flag going true. The altitude at that point per the data was ~1.7 meters. Taking that with a "grain of salt" so to speak, the "motor obstruction" message could have possibly been ( and I am grasping here ) impact with the water. The time between the two was roughly 700ms. It's really hard to say definitively.

 

[sar104]

Completely agreed that the sudden excursions could very well be an ESC failure. Also looking back at the 2 flags, the "motor obstruction" occurred after the " Not enough force" flag going true. The altitude at that point per the data was ~1.7 meters. Taking that with a "grain of salt" so to speak, the "motor obstruction" message could have possibly been ( and I am grasping here ) impact with the water. The time between the two was roughly 700ms. It's really hard to say definitively.

View attachment 110690

If we ignore the motor obstruction message it looks much like a lost prop. But the motor obstruction notification precedes impact with the water, since the aircraft continues to descend and spin for another second, so I think that we have to assume it's real, and indicative of an ESC issue.