P3S's prop flies off mid flight

[buford]

Props can and do come off in flight. That's why DJI added prop locks to the Inspire props and changed to the composite hubs on P3 props. DJI claimed that active braking could make a prop come off. The other possibility is a glitch in the ESC. If one of the three motor wires is disconnected the motor will lock up and the prop will fly off unless it was really tight.
Here is a video of trying to make a prop fly off by manually stopping the motor. It was difficult but possible. At the end, you can see what happens if you disconnect a motor wire.

This video proves that if you jack with it enough, and grab at the motor and stop it dead enough, and loosen the prop enough, you can get it to come off. It proves very little to me. Its like saying a gun will go off by itself if you drop it on concrete. It may, and it may not. But you have to drop it on concrete for days before it might happen.

 

[telescott]

How can a prop come off if it was tightened completely? Did you use the tool to hold the motor or just spin them on by hand?

I never tighten them without the tool to hold the motor, I did at one time but I am worried that with the braking system I have heard that they can spin off if not properly tightened.

 

[TheRealNick]

This video proves that if you jack with it enough, and grab at the motor and stop it dead enough, and loosen the prop enough, you can get it to come off. It proves very little to me. Its like saying a gun will go off by itself if you drop it on concrete. It may, and it may not. But you have to drop it on concrete for days before it might happen.

There are at least 3 .dat files I looked at that had a prop come off mid flight. It is listed on the DJI forum in in the top 10 reasons.... There is another recent post where a guy would just spin them on until one came off an now he tightens them. If you just spin them on I think it is just a matter of time until you loose one during a flight...

 

[buford]

There are at least 3 .dat files I looked at that had a prop come off mid flight. It is listed on the DJI forum in in the top 10 reasons.... There is another recent post where a guy would just spin them on until one came off an now he tightens them. If you just spin them on I think it is just a matter of time until you loose one during a flight...

I spin them on, then tighten them 1/8 turn. I've never had, nor do I expect to have one come off. The video you posted didn't convince me that one could come off under normal circumstances.

 

[TheRealNick]

I spin them on, then tighten them 1/8 turn. I've never had, nor do I expect to have one come off. The video you posted didn't convince me that one could come off under normal circumstances.

Your procedure is very similar to mine and I think you are all set. I think you mean someone else's video. But here is one of a crashes I investigated, the upper chart shows motor speed and load, you can see speed goes up and loads goes down when the prop is lost....the chart below that one is altitude.

The full video was posted in the original thread, it is here: DJI_0074 Crash.MOV

 

[buford]

Your procedure is very similar to mine and I think you are all set. I think you mean someone else's video. But here is one of a crashes I investigated, the upper chart shows motor speed and load, you can see speed goes up and loads goes down when the prop is lost....the chart below that one is altitude.

The full video was posted in the original thread, it is here: DJI_0074 Crash.MOV

I saw that video when it was posted. It doesn't show without a doubt that a prop came off. It just shows the crash. It might have been a bird hit, it might have been some other anomaly, it could have been that one of his motors shelled out in mid air. But, it still stands that any failure, no matter what it is, is more than likely due to something other than the prop just spinning off. Yes it could be the threads are worn and let go, or that a previous crash did something to the hub, but I for one will not worry about props coming off. I change them if there is any defect in them, and install them like I said before.

 

[TheRealNick]

I for one will not worry about props coming off

I wouldn't worry because you tighten your props on. If you just spun them on then I would worry, that is all I am trying to say. Hand tighter your props 1/10 - 1/8 of a turn....

 

[buford]

I wouldn't worry because you tighten your props on. If you just spun them on then I would worry, that is all I am trying to say. Hand tighter your props 1/10 - 1/8 of a turn....

I do 1/8, cause I cant imagine breaking it down any further. I built houses for 25 yrs and didn't work with computers or tiny screws or the like.

 

[syotr]

This video proves that if you jack with it enough, and grab at the motor and stop it dead enough, and loosen the prop enough, you can get it to come off. It proves very little to me. Its like saying a gun will go off by itself if you drop it on concrete. It may, and it may not. But you have to drop it on concrete for days before it might happen.

As I said, it was difficult to make it happen manually. I believe in most cases when a prop come off in flight, it is caused by a problem with the ESC. I could make it happen every time by disconnecting a motor wire, even when the props were snugged up pretty tight.

 

[buford]

As I said, it was difficult to make it happen manually. I believe in most cases when a prop come off in flight, it is caused by a problem with the ESC. I could make it happen every time by disconnecting a motor wire, even when the props were snugged up pretty tight.

It doesn't haunt me at night so I cant sleep is all I'm saying.

 

[Sean808080]

Yes, i believe one of my props came off and of course crashed. Yes, it was the standard self-tighting props and unmodified phantom 3 pro. I had something like 50 flights under my belt and have been flying RC units for years.

This is what I wrote to DJI:
I was flying my Phantom 3 Pro (1/9/2016) something over 100' above ground (estimate) when suddenly the aircraft turned upside down and crash. I believe this was due to losing a propeller in flight. I say this because: 1) The remains of the phantom after the crash showed 1 missing prop, 1 broken prop and two other props and landing gear unharmed; 2) The video recovered verifies that the aircraft did flip over and crashed; and 3) research shows that others have suffered the same fate from a missing prop or bad motor.

The phantom seems to have a design flaw or software limitation that does not allow the aircraft to fly with 3 motors. It seems inevitable that the aircraft will lose a prop or a motor will stop working but it is impossible for a pilot to know when this event will happen and take action. I find this not only to be an expensive flaw but a very dangerous flaw that could kill someone. Not only am I requesting a new Phantom 3 Pro but a solution to this safety hazard. I do not want to be victim of such an event or someone responsible.

and what was the response? Did DJI cover it for you?

 

[erlik-khan]

this is an inherent defect in the design (among many others), compounded by you probably not tightening them enough as just mentioned.
That is why the P4 has quick snap on props that can't spin off. Props that spin off and on is such a dumb idea.