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P3A crash, any ideas?

Discussion in 'Pro/Adv Discussion' started by Pete44, Jul 4, 2015.

  1. Pete44

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    Hi Guys,

    Wondering if anyone might be able to shed some light on the below?



    Was descending slowly and rotating to double check the area when it continued to rotate and fall from the sky...

    I noticed it was rotating quite quickly and when i tried to back it off it seemed to continue doing so. I found the P3A missing a rotor when i recovered it

    using 1.28 firmware on a Android phone.Checked the logs for any signs of abnormality but all looked reasonable.

    The footage was originally unreadable but i was able to salvage most of it, including the final few moments using 'Video Repair Tool' if anyone needs to do the same.

    Any help/ideas appreciated.

    Thanks,
     
  2. bobmyers

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    Looks like the missing prop may be the issue. Did you have genuine Phantom 3 Props with the composite center threads?
     
  3. Pete44

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    Yeah, originals from the box it came in.
     
  4. bobmyers

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    It would be very unusual for that P3 prop to unscrew since they actually become tighter after the engines start. Did you have any error messages or signal losses?
     
  5. Pete44

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    That's what i thought too, unless it was a motor failure and coincidentally one of the props came off when it hit the ground? i haven't tried starting the P3A again as the battery was ruptured.

    Nope no errors or signal loss, was out in the country with perfect LOS, it was probably 400ft away from me when it went down.
     
  6. bobmyers

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    A prop could well come off on a ground impact-- was this the second prop or the missing one? a thorough check of the motors when you get a battery would be in order. Could have been an ESC failure to one of the motors -- that fast yaw rotation tells you right a away that the motors are not operating at the right speed. Im not really sure what the speed relationship should be on all four motors when the aircraft is yawing-- but one the quad experts on the forum may chime in with that info.
     
  7. Pete44

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    Only one prop came off, the others were still on. No chance of getting another battery (pretty remote area) and as it hit the ground pretty hard 2 of the motors are full of dirt and don't spin freely anymore, camera was ripped off and substantial body damage etc.

    Had plenty of battery left at the time and the logs show a steady voltage readout.

    https://drive.google.com/file/d/0BzARuKItAJGhVHM4eXhFdHBmb00/view?usp=sharing

    See above for the full log.

    Yeh i don't know if that motor data is stored on board the P3A at all or if it will be assessed when i send it to them, anyone know?

    Thanks for your help so far bobmyers
     
  8. FRM

    FRM

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    It looks to me like your propeller stripped out and fell off






    QUOTE="Pete44, post: 438226, member: 29666"]Hi Guys,

    Wondering if anyone might be able to shed some light on the below?



    Was descending slowly and rotating to double check the area when it continued to rotate and fall from the sky...

    I noticed it was rotating quite quickly and when i tried to back it off it seemed to continue doing so. I found the P3A missing a rotor when i recovered it

    using 1.28 firmware on a Android phone.Checked the logs for any signs of abnormality but all looked reasonable.

    The footage was originally unreadable but i was able to salvage most of it, including the final few moments using 'Video Repair Tool' if anyone needs to do the same.

    Any help/ideas appreciated.

    Thanks,[/QUOTE]
    It looks
     
  9. Pete44

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    what would cause this 'stripping out' ? it has done probably less than 5 hours flight time from new
     
  10. robinb

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    Did you find the missing prop ?

    Its condition could be the key.
     
  11. Pete44

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    yeh all props are still in one piece with obvious chips taken out of them from the impact. Should i be looking for something in particular?
     
  12. robinb

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    The one that came off, what is the thread like, does it lock when fitted ?

    Do you give the props a nip with the spanner when you put them on ?
     
  13. Woods

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  14. Pete44

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    CSC?

    ok so the prop that came off doesn't tighten to the motor anymore, spins fairly freely, the inside does look like the threading has gone.

    Yeh i always double check the props with the spanner when going from transport>>operation. They were all tight.
     
  15. DrJoe

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    Pretty sure your descent was straight down, then your rotation begins (controlled). I'd bet the farm that you induced VRS (vortex ring state). The prop was just impact damage.
     
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  16. robinb

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    Sounds though from his reply above that the prop might have detached in flight ?

    Certainly something happened in the last few seconds as it tumbles out of control.
    The spinning before had maybe the prop was starting to strip its thread and not going as fast as it should.
     
    Skip holden likes this.
  17. Pete44

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    Yeh, not sold on the VRS idea, by memory it was maybe a 50% descent speed maybe a tad more but certainly not 100% even though its done many 90+% speed descents before.

    The more i watch the footage, as soon as it starts to rotate it looks too quick to be normal to me. I cant remember my exact stick inputs at the time and Android doesn't report them unfortunately.... and the way it suddenly jolts looks more motor/prop related i would of thought.

    dodgy rotor threading perhaps?
     
  18. robinb

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    I am pretty certain its a bird strike.

    If you slow the video down on your computer and watch at around the 11 second mark you can see a bird wing/tail
    I can't catch the exact frame on youtube. its just before this one at the top right corner.

    Screen Shot 2015-07-04 at 14.42.53.png
     
  19. dysan911

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    Or ^^^^^^^^^^^ the prop flying off.
     
  20. robinb

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    just before. Screen Shot 2015-07-04 at 14.51.38.png