DJI Drone Help Forum

Flipped over and crashed during landing

#1

Hi everyone,

Can you help me to diagnose this crash?

At first, I flew my aircraft for 10 minutes and landed successfully. Then, I took it off again and flew for another 4 minutes. I used return home button and it returned successfully and hovered on top of my head (40 meter height). Then I started to land it manually (I had one bad experience about auto landing so I always do it manually later on). When it was down to like 14 meters, it suddenly started flipping over and then I saw Warning-Motor idling (loose or missing propeller) on my app. It kept flipping over and crashed. (Notice that the warning was after it started to flip over)

I don’t believe I made mistake on installing propeller since I made sure each of them are tight before taking off and it had flew for 14 minutes.

here is my flight log:
https://www.phantomhelp.com/LogViewer/SPN4PJVPN1HTN8GG9Y48/

Any thought will be helpful! Thanks

0 Likes

#2

Where were all of the props when you retrieved your Phantom at the crash site?

0 Likes

#3

Must say it’s almost impossible not to fit the props correctly unless you get a crossed thread, which again is almost impossible to do from the attachment mechanism. Very strange scenario…

0 Likes

#4

We’ll have to wait for the OP to confirm, but it looks like a prop flew off mid-flight. In most cases, that has happened when the prop was not hand-tightened prior to takeoff, when using a damaged prop (like a prop with a cracked hub), or when using 3rd party props or props not specifically designed for the P3 (like a P2 prop with a metal hub).

0 Likes

#5

Yes, it looks to me like there was a propulsion issue with the left front prop/motor. Although it could have been the left back.


There was a CCW roll indicating the left side lost propulsion. The pitch down wasn’t pronounced enough to conclude that it was front prop. To know for sure it’s necessary to look at the .DAT which will have higher sampling rates, motor and gyro data. Look here to see how to retrieve the .DAT

1 Like

#6

Interesting comment there about the “metal hub” msinger. I just bought four spare props, advertised for the Advanced, and they have metal hubs?? Must admit having just tried to check balance them and the bore prior to the thread is slightly bigger than on the original plastic ones. Should I be worried??

0 Likes

#7

While OEM DJI props with metal hubs also fit P3 models (and some P3 owners use them), DJI does not recommend they be used with P3 models. The plastic hub creates more friction when turned since the hub isn’t made of smooth metal. I guess DJI’s idea is that it makes the props more secure (less chance of unwinding mid-flight).

0 Likes

#8

Actually, there was one missing.

0 Likes

#9

@cheddarman If this makes it clearer, generally speaking these props ( If not properly tightened ), will loosen upon a hard change in throttle, due to the motors slowing down very quickly upon release. The metal hub props do not secure as well as the OEM plastic hubs. In relation to this instance you can see the probable prop loss below:

0 Likes

#10

So, that explains what caused your crash. See my post above regarding things that can cause props to fly off mid-flight.

0 Likes

#11

But I definitely check all of them before taking off. Since I made a mistake two months ago when I didn’t install one prop in the right direction and thus it crashed just after taking off. But this time, it flew successfully for a long time and the crash happened during landing.

I am using the right version of props. So now, the only reason is that one prop cracked during landing? There was some wind during this flight and I don’t know if this hurts prop.

0 Likes

#12

Do the motors actually reverse when you descend quickly? If so I can see how a prop could come off in flight under this condition. While climbing/under load the threads are self tightening but when you take the power off, its possible for the prop to try to reverse thus unscrewing itself :face_with_raised_eyebrow:

0 Likes

#13

Correct, however the motors do not reverse, they simply slow down very quickly, which can cause loosening.

0 Likes

#14

So I actually finished one flight before this flight. I landed successfully and found that still have ~50% battery, so I didn’t do more checking and taking off again.

So is it possible that propeller got loose during my first landing and thus caused problem during my second landing?

Here is my first successful flight:
https://www.phantomhelp.com/LogViewer/IJ7HFCF2DU16E2ZTZROL/

0 Likes

#15

A little worrying to say the least! Must give Them a little extra tweak when installing in future!

Something to bear in mind before EVERY flight victorsun (and me)!

0 Likes

#16

Can you send me a link where you post things that can cause props to fly off mid-flight? Thanks!

0 Likes

#17

One small piece of advice here. When landing manually, ease the aircraft down. Don’t attempt to land too quickly ( Except in an emergency situation ). As noted in the graph above, going from full down throttle to zero can eject a prop.

2 Likes

#18

@victorsun This is from your good flight. Notice again the extreme’s in the full throttle down and zero ( Green line )…

0 Likes

#19

Where do these files hide, would like to look at mine to see I’m being a bit heavy-handed!

0 Likes

#20

These are on the device you fly with. You will need to upload the files for viewing. ( The aircraft has it’s own flight recorder as well, but that is for more in depth analysis.) You can upload them at the link below. Instructions are on the link:

Log Viewer

0 Likes