Drone crashed! Help me determine what went wrong...

[jacamp2222]

My DJI Phantom 3 Advanced crashed yesterday. I was flying about 100 ft above the treeline, when suddenly my drone began to spin out of control, crashing into the woods. I was able to retrieve the drone, and to my surprise, the damage did not seem too extensive.

I think the crash was caused due to a lost propeller; however, I made sure all four propellers were secured before taking off. Also, the crash occurred well within 10 minutes of liftoff, which makes me think something went wrong internally; perhaps one of the motors? Here is a link to the flight log, which I attempted to analyze, but I wanted to get other opinions before contacting DJI. I also uploaded the .txt file if needed.

DJI Phantom & Mavic Flight Log Viewer - PhantomHelp.com


Here is a link to a video of the crash

Drone Crash.mp4


Here are some photos of the damaged drone

Drone Crash - Google Drive



Any advice or suggestions for my best course of action would be greatly appreciated. Thanks!

 

[sar104]

It's pretty clear that a propeller (probably front right) comes off at 12' 5.4" into the flight at 360 ft, at which point the attitude numbers go berserk and the aircraft loses altitude fast. At 12' 6.5" the FC reports loose or missing prop. The only thing that puzzles me is why the flight log ends 4 seconds later at 12' 10.3" while it is still descending and spinning, and at a reported altitude of 160 ft (above takeoff point), since the video keeps going much longer than that.

 

[Numone]

Hi jacamp2222 and welcome to PhantomPilots.
Looking at the record, at 12m 6s you get the message "Motor Idling (Propeller Loose or Missing)". I guess that your thoughts as the cause of the crash was correct, especially given the flight footage too; that's a typical prop loss downing I'm afraid. I presume a prop was missing? At least it seems the AC isn't too bad which is great.

 

[jacamp2222]

Yes, when I recovered the drone it was missing a propeller. I'm just trying to figure out the cause of the lost propeller. Is there any way to tell if something internally failed? I tried attaching a new propeller to the specific thread where the old propeller slipped off with no issues. I don't see any signs of stripping of the thread.

 

[sar104]

The cause is generally failure to tighten them sufficiently when installing but it can also be caused, in some cases, by ESC failure. However, the FC message regarding a loose or missing prop I think rules out ESC failure. Did you try starting up the motors again?

 

[jacamp2222]

I have not tried to start it back up. I was going to give the drone time to dry out in case moisture was present because it took me two days to find it. I will try to fly it this evening with brand new propeller. If the propeller was tightened properly why did the drone fly so well for 10 or so minutes? Could there be something wrong with the actual propeller. I couldn't find the lost propeller, so I have no evidence of its condition.

 

[sar104]

I have not tried to start it back up. I was going to give the drone time to dry out in case moisture was present because it took me two days to find it. I will try to fly it this evening with brand new propeller. If the propeller was tightened properly why did the drone fly so well for 10 or so minutes? Could there be something wrong with the actual propeller. I couldn't find the lost propeller, so I have no evidence of its condition.

It's possible that the hub was cracked - that could cause it to fail. Can you describe your procedure for tightening the props? Spin on, hand tighten, tool tighten etc.? How old were the props?

 

[jacamp2222]

It's possible that the hub was cracked - that could cause it to fail. Can you describe your procedure for tightening the props? Spin on, hand tighten, tool tighten etc.? How old were the props?

I simply rotate the props in the direction of the lock symbol until they are fully threaded on, then slightly tug to make sure they are secure. I was under the impression that the props are self-tightening, and no tools are necessary to tighten.

 

[macoman]

I simply rotate the props in the direction of the lock symbol until they are fully threaded on, then slightly tug to make sure they are secure. I was under the impression that the props are self-tightening, and no tools are necessary to tighten.

I want to let you know something, in my phantom 3 standard... I noticed that if you tried to tight the prop in the direction of the lock symbol... sometimes if you pushed too fast, it will tied quickly... but then I realized it that it's not correctly tied at all, you need to do it again, until it is secured and correctly tied. I am not said that this may happened to you but I see it happened to me and realized that if folks are in the hurry doing this and they think that the props are correctly tied, they may end up with the same fate.

 

[sar104]

I simply rotate the props in the direction of the lock symbol until they are fully threaded on, then slightly tug to make sure they are secure. I was under the impression that the props are self-tightening, and no tools are necessary to tighten.

That should be good enough, and it always worked for me with the P2s, but I now think, having read of enough failures, that they should probably be tightened more than that to prevent motor decereration from spinning them off.

I'm glad I don't use threaded props anymore.