P3P suddenly fell from the sky

[jwmcgrath]

@hwortman, @sar104, @Jthomp, LOL! sar104 is right. It's not a bird. It's the edge of my iPad cover. This video was from my iPhone camera recording my laptop running the recovered video on VLC. (The video was truncated because the camera didn't shut down properly. I could only recover the video in h.264 format, which only VLC could play.) My phone was resting on my wife's iPad because it has a flexible stand (mine is fixed angle). But her iPad is white, so I tried to use my black iPad to cover the reflection. But it went into my iPhone's range.

I've since discovered how to record the screen directly. This is a version without reflections and iPad cases coming into view. ]

I can't even begin to describe the laughter and Wile E. Coyote setup this sounds like when you try to imagine the visual!! [emoji23]

 

[sar104]

That's better. I'm not sure about the P3, but on both the P2 and the P4 the camera, if it looks up, can see the propeller hub over the top of the motor housing. In the frame below there does not appear to be a hub visible. Further evidence, perhaps, that the front right propeller did fly off.

 

[42FrankZ]

Yep, read that after I posted... that's really what I mean when I say seizure, or motor failure, or some other contributing factor other than the propellor flying off because it wasn't tight enough.

Ive read of many who believe that's possible (simply flying off because it wasn't right enough). That's the one I have a hard time with.

I've posted that pulling your battery out causes two of the props that are rotating in the same direction to fly off. I have no verifiable proof but I'm certain that the sudden power loss contributed to motor behaviour in a way that made the propellers fly off, but I can't prove it.

Maybe the @stotr test replicates the same behaviour I'm trying to describe.

I pulled the battery once and two props flew off.

 

[KHobbs5]

No - if that happened, which would be difficult since they are oppositely threaded, it would not be able to take off and fly.

Here's another theory.

I was recently installing my propellers for a flight when I discovered that one of them would not tighten. I then figured out that the threads in the propeller were stripped, almost certainly from my overtightening them in the past.

If your propeller was nearly stripped, as mine was, then a quick increase in motor speed in flight might have finished stripping it and causing it to fail. The result would have been the same as if it had suddenly decreased speed and spun the propeller off.

 

[sar104]

Here's another theory.

I was recently installing my propellers for a flight when I discovered that one of them would not tighten. I then figured out that the threads in the propeller were stripped, almost certainly from my overtightening them in the past.

If your propeller was nearly stripped, as mine was, then a quick increase in motor speed in flight might have finished stripping it and causing it to fail. The result would have been the same as if it had suddenly decreased speed and spun the propeller off.

I've never encountered that. So the hub thread was stripped but the stud on the motor was fine?

 

[KHobbs5]

I've never encountered that. So the hub thread was stripped but the stud on the motor was fine?

I just got the propeller out of the trash and inspected it further. It wasn't stripped after all. The threads in it were buggered up enough that it wouldn't "start" onto the stud threads. I was able to work in onto a screw the same size and then later onto the motor stud.

 

[Buddy Moran]

I just got the propeller out of the trash and inspected it further. It wasn't stripped after all. The threads in it were buggered up enough that it wouldn't "start" onto the stud threads. I was able to work in onto a screw the same size and then later onto the motor stud.

The threads were fine. I can easily spin the props into the threads prior to tightening them, and spin them off after untightning. And I'm very sure they were tightened well. I wouldn't have thought the AC would have reached over 2 miles, or 11 minutes in the air otherwise (until I read earlier posts saying they tighten while spinning).

 

[Rob65]

Hi @Rob65. This was flown in Thailand, too. But at 6:00am, and about 28C. I don't notice any significant warmth in the props after flying here. In fact, the props seem tighter and require more effort to remove after flying 10-20 minutes. But thanks for the suggestion. I will consciously tighten more than finger tight next time. Do you think that will cause more wear on the prop thread, though?

Props are considered a consumable item for many reasons including accidental strikes, abbrasive wear and thread deformation in the hub. I have been "nipping up" my props every time since and the threads are still fine. I replace them after a minor strike with a bird or similar.

 

[itrocks4u]

Unfortunately, if the entire prop, including the hub, was missing then that is most likely the cause of the failure. The sudden rotating fall is exactly what losing one motor will produce. The front arm that drops first (front right, as seen in the video) would be the motor that I would expect to be missing its prop.

How/Why would the prop fall off? Aren't these self-tightening, at least that's what the instruction videos say?

 

[sar104]

How/Why would the prop fall off? Aren't these self-tightening, at least that's what the instruction videos say?

I'll take a wild guess that you have not read through this thread.

 

[itrocks4u]

I'll take a wild guess that you have not read through this thread.

Bang on!

got super excited.

 

[mdowney58]

How/Why would the prop fall off? Aren't these self-tightening, at least that's what the instruction videos say?

I can't explain how the self locking props work, but on my P3 Standard the props are threaded.
They are self tightening, as the motor rotation is opposite the thread, so as the motor increases speed, the effect would be to tighten the prop.
They have been known to come off in some situations (not tight enough) when the motor brakes, or slows down rapidly, and momentum is causing the prop to want to continue turning as it was, which in relation to the braking motor, allows the prop to thread off.

 

[Super Dave]

(Sorry if this has been covered, but i skipped ahead)
How far from the crash was the missing prop found?
If it was found any distance from the crash, that is how far it fluttered down, while your aircraft took the direct route down.
Common FAA investigative technique may show your prop came off.

 

[msinger]

How far from the crash was the missing prop found?

If you watch the video above, you can see the prop fly off.

 

[Miltrez]

Can't be ruled out, but if you look at the video frame by frame it appears that the gimbal is simply trying to keep the camera pointed in the forward direction while the front right of the aircraft suddenly drops. Are you suggesting that a bird knocked the prop off? If not, the aircraft would have recovered, presumably, rather than crashing with a prop missing.

I also can't imagine how a bird could be so situationally unaware that it would collide with a noisy, slow-moving Phantom, but that's a different issue.

I only have 2 hours flight time. On 6 separate flights, I had to get tha hell outta dodge because of kamikaze finches and psychotic sparrows. They are in nesting season over here and go apeshit when a drone gets anywhere close to them...say like the next zip code...smh

 

[Buddy Moran]

(Sorry if this has been covered, but i skipped ahead)
How far from the crash was the missing prop found?
If it was found any distance from the crash, that is how far it fluttered down, while your aircraft took the direct route down.
Common FAA investigative technique may show your prop came off.

Super Dave, I never recovered the prop. The aircraft was recovered from a creek. After I recovered that and the detached camera, I didn't bother looking for the prop. But from the map trace of the route, it probably fell off about 20 meters away. (It suddenly veered to its right and moved in a crooked line for a short while.) I realize the prop probably came off. But after flying for 11 minutes, what would make the prop suddenly come off? Earlier responses experience prop tightening during flight. Another response showed an experiment where when the motor suddenly stopped (power removed) the prop shatters and flies off. In addition to this, I was sure I put the props on tightly. That's part of my pre-flight checklist.

 

[Haterade]

My P3S fell from the sky at 200 feet on an RTH about 15 minutes into a flight. Props were all tightened prior to flight. I couldn't find one of the props, so I assume it flew off. I have video, and it was well above any obstructions and the sky was as clear as glass. I thought there was something wrong with my P3, but I was too new to put my finger on it. One of the motors, the one that I think flew off, just spun on 'differently', even with different props.

DJI covered the 180 dollar repair under warranty, including shipping both ways. Got a new drone (Greggs drone, lol) and it's been rock solid with about 100 flights on it since. I have read several threads where they will flat out deny a warranty if it happens within a few min of taking off claiming it wasn't tightened. That's one of the reasons I always whip mine around at low level at let it hover a few min while I screw with camera settings. Figure if it happens again, I'll be good.

 

[macoman]

My P3S fell from the sky at 200 feet on an RTH about 15 minutes into a flight. Props were all tightened prior to flight. I couldn't find one of the props, so I assume it flew off. I have video, and it was well above any obstructions and the sky was as clear as glass. I thought there was something wrong with my P3, but I was too new to put my finger on it. One of the motors, the one that I think flew off, just spun on 'differently', even with different props.

DJI covered the 180 dollar repair under warranty, including shipping both ways. Got a new drone (Greggs drone, lol) and it's been rock solid with about 100 flights on it since. I have read several threads where they will flat out deny a warranty if it happens within a few min of taking off claiming it wasn't tightened. That's one of the reasons I always whip mine around at low level at let it hover a few min while I screw with camera settings. Figure if it happens again, I'll be good.

If you put the props properly and tight, no way they can go off unless one of the motor go off of the aircraft.

 

[Buddy Moran]

My P3S fell from the sky at 200 feet on an RTH about 15 minutes into a flight. Props were all tightened prior to flight. I couldn't find one of the props, so I assume it flew off. I have video, and it was well above any obstructions and the sky was as clear as glass. I thought there was something wrong with my P3, but I was too new to put my finger on it. One of the motors, the one that I think flew off, just spun on 'differently', even with different props.

DJI covered the 180 dollar repair under warranty, including shipping both ways. Got a new drone (Greggs drone, lol) and it's been rock solid with about 100 flights on it since. I have read several threads where they will flat out deny a warranty if it happens within a few min of taking off claiming it wasn't tightened. That's one of the reasons I always whip mine around at low level at let it hover a few min while I screw with camera settings. Figure if it happens again, I'll be good.

Haterade, thanks for sharing your experience. Mine seemed exactly like yours, although about 4 minutes shorter (11 minutes flying time). What was your new drone (Greggs drone? I don't get it)? How was the P3 after the repair? I'm worried after a repair the experience will just recur.