Bizarre Phantom 2 crash

[wntofly]

Has anyone ever had all 4 props spin off in mid flight? Went for a late afternoon flight today and after reaching my 1900 M distance limit I rotated 90 degrees to the right and then began the trip home flying sideways to film a new subdivision. After about 50 meters or so my FPV video went to all snow instantly and after a short minute I flipped to F/S to try and initiate the RTH. A few long minutes passed and after no sign of the Phantom returning, I decided to get in the truck and go track it down. I drove to a point where I knew I was close to when I lost FPV video and within a few minutes located the Phantom on the ground. When I picked the phantom up I discovered one of the motor housings was missing as well as all four props. Not even broken pieces of a prop anywhere. After a quick search of the area I found all 4 props in perfect condition and all 4 relatively close to each other....... but 35 meters or so away of where the phantom came to rest. Not sure if the motor housing came off in flight or came off due to the impact with the ground. I may go back in the morning to see if I can locate it. It appears that all 4 props departed the quad in flight at the same time and landed fairly close to each other.
I am thinking that maybe a sudden loss in power shut off the video tx and maybe stopped the motors abruptly causing the inertia of the spinning props to spin themselves right off the motors. Can that even happen? The Battery showed 11.4v or 70% at the time of FPV video loss and after getting back home still had 2 bars or half charge left. I was not ascending or descending at the time only flying sideways to the right. At 50 meters high there was no collision with anything on the ground (buildings, trees, or power lines) and no sign of hitting a large bird of any kind.

Can someone with more smarts and experience than me shed some light on what might have happened? I want to learn from this to hopefully prevent it from happening again, and to help others avoid it as well.

[youtube]http://youtu.be/O-B1n12wAr0 [/youtube]

HELP!!!!!

 

[4wd]

If a motor stops abruptly the momentum can spin them off, hard to explain how all the motors could lock up simultaneously though.
In any case a dead motor will result in crashing to the ground whether or not props stayed on.

If they are put on correctly it's almost impossible for them to come off in normal flight.

 

[ianwood]

Most likely your battery pooped itself and shut down. There's no sign of life in the video after the motors quit. LEDs off, vTX off. There are a few incidents like this. Contact DJI with the video. They should repair/replace everything without question. Make sure they get the battery so they can possibly figure out why it failed.

My guess is that there is some sort of fusing / short circuit protection in the battery that tripped due to a transient power load. Bad design. Likely the cut off threshold is too close to possible regular use output limits.

The props coming off is possible if the motors all shut down as they did in this case.

 

[wntofly]

Thanks 4wd and ianwood for the responses. Barely slept a wink last night trying to figure out what happened. That does make sense that if the battery self ejected or shut down all the motors would have stopped at the same time launching the props simultaneously. It is hard to visualize how the battery could slip out when the little buggers are so hard to pull out when on the ground!

What's the most productive way to contact DJI, phone, email, letter,......All three????? I think I remember reading somewhere DJI being not very easy to communicate with. Wish me luck!

Jim

 

[ianwood]

It is very unlikely your battery slipped out. I'd bet a safety circuit kicked in.

Not sure of the best way to contact DJI. Maybe someone else can answer that.

 

[wntofly]

Update: I started taking pictures of the damage from all angles and then slowly removed the top of the shell so I could carefully work the battery out to store in an ammo box to be on the safe side. After successfully getting the battery out I started to check all the connectors and wiring looking for anything that might have caused the power failure. I inspected the spades that the battery slides onto when inserted into the phantom and then followed the black and red wires back to where they are soldered to the main circuit board. The black ground wire checked secure but when I checked the red wire it was noticeably loose (wiggled) where it attached to the board. I went and got my other battery, inserted it and powered it on. While the phantom was on I was going to wiggle the connection to see if it lost power and as I made the first two little tugs the red wire came right off shutting down power to the Phantom. I took some pictures and if I can figure out how to attach one to this post it should be plain as day as to what might have happened. Only thing is did this loose connection cause the crash or did the crash cause this loose connection?????????

 

[Pacific Barbarian]

Thats a good question.

 

[Noël]

I've had something similar a long time ago (never crashed!).

The only reason that it was still making contact was because of the pressure of the other cables and the white cable tie (zip tie).

[youtube]https://www.youtube.com/watch?v=LkQX4vULlZ0[/youtube]

More info about this subject here: viewtopic.php?f=7&t=6148

 

[wntofly]

My Oh My, does that look familiar!!

 

[shartlza]

That is probably the cause, that looks like it was a bad soldering joint. It should have not been that easy for it to come off the board. With enough vibration it could easily loose contact with the board, shutting everything down. If you are going to contact DJI the best way is to call because they will not do any sort of tech assistance or issue a RMA to return it to them through email, only over the phone. Trust me i have done this alot in the past few months. Also expect a 4-6 week turn around.

 

[wntofly]

That is probably the cause, that looks like it was a bad soldering joint. It should have not been that easy for it to come off the board. With enough vibration it could easily loose contact with the board, shutting everything down. If you are going to contact DJI the best way is to call because they will not do any sort of tech assistance or issue a RMA to return it to them through email, only over the phone. Trust me i have done this alot in the past few months. Also expect a 4-6 week turn around.

Thanks for your input, I think I have to agree with you. Nothing else I could find appears to be wrong that would cause total loss of power. I have tried to make contact with the original dealer as DJI requests.... So far no response from them so I guess I will take the next step and give DJI a call today. I hate the thought of being grounded for 4-6 weeks, I almost feel sorta naked not being able to go fly. Is that weird??? :lol:

 

[SteveMann]

The props were definitely off before the crash. Here's two frame grabs from your video.

 

[Bluegrass]

I agree with shartiza but what about your video. Even losing power, the battery on the GoPro should have been charged enough to continue recording after the Phantom lost power and fell from the sky. That should be some interesting video to see.

Append: I'm confused Steve. Are you wintofly?

 

[wntofly]

Not only that Steve, but both those frames show the LED's were off.

Bluegrass: Those frame shots were from the GoPro video that "Did" continue to record and the window on the lower right was from the FPV video Tx that died when it lost power due to the alleged bad solder joint. I tried to post a link to the You tube video in my original post but must have done it wrong. (Newbie to the forum)

[youtube]http://youtu.be/O-B1n12wAr0[/youtube]

 

[Noël]

I wonder if some kind of "ESC FET drag" occurs when the red wire (+) touches the black wire (-) when spinning full speed.
If so, than this most probably caused the props to spin off in mid-air due to the motors drastically slowing down!

 

[ianwood]

if the V+ and GND wires actually touched, you would likely see some arc burns and/or melting of the wire insulation. The battery would have dumped a huge amount of current until the battery's overload circuit kicked in.

 

[Noël]

You are correct. I wasn't thinking straight.

 

[ussvertigo]

Hey my first thought was some one shot the dam thing down, but the pictures of the battery leads solder to the main board show heat stress on the insulation, possible heat build up from high resistance from poor solder connection. But the prop mystery, only if the motors stopped like a brake was applied I could see the props spinning them selves off, maybe at the break of current the motors split second reversed, that would do it. But there is usually no mystery in most of our crashes, but I like this one.

 

[wntofly]

Hi All,
I wanted to pass along an update as to the status of my Phantom 2.

The DJI repair team I feel did an amazing job in the repair of the Phantom and in record time. They received it on a Thursday and I just got it back the following Friday. An 8 day turn around time when I was expecting 4-6 weeks!!!!!!!!! Wow was I surprised. Thank you DJI!!!!!

Too windy on Friday to give it a test run so I had to wait until this morning to take it out for a flight. The Phantom itself seems to be back to normal although I was very conservative staying very close in and relatively low. I think it's going to take some time to slowly re-establish the trust I once had in it but so far so good on the Phantom itself.

The Gimbal however is not back to normal. Not sure if it was replaced or repaired but I immediately noticed some strange behavior the minute it was turned on. Strange noises coming from the motors I have not heard before and I noticed the tilt function control is opposite of what it was before. (Can that be reversed in the settings somewhere? I looked but was unsuccessful in my hunt.)

In flight I can visibly see the gimbal showing erratic behavior and it is not stabilizing like it should. The Horizon is tilted and as I flew side to side with the Phantom you could see the horizon tilt back and forth which I never had before. The tilt function also shows jerky erratic behavior that is opposite from before when it was silky smooth.

So to the experts out there: Is this something that can be corrected in the settings somewhere or is this showing symptoms of a defective gimbal? I will give DJI a call on Monday but wanted to throw this out for comment in case I can remedy it here without sending it back in. I did check and everything has had firmware updates already and I recalibrated the controller before taking to the air.

Anyway I wanted everyone to know how fast DJI got the Phantom back to flying condition and back to me way sooner than I expected!!!! Thank you once again DJI repair team.

Jim E.

 

[smallman28]

My gimbal operation was reversed in the last update I did.
Go into software and set it as reverse and opposed to normal.