XAircraft Strange crash diagnosis ...very odd

VIQuad

VIQuad

Member
I was flying around the other day, stopped to hoover 3 ft off the ground and all of a sudden the quad just flipped over to the right and crashed in the grass. Broke the #1 arm on the inside of the quad where it connects to the frame.

See the Blackbox log here - http://log.xaircraft.com/#2014_05_18_112855.750_186.1.02.51

See the video here(happens at 2:50) - https://www.youtube.com/watch?v=LlySBPxGMdc

If you note on the black box file, right before the crash I was just hoovering there and not giving any inputs. I was about 3ft off the ground and all of a sudden it rolled over and slammed into the ground - OUCH! Very odd to say the least. I was shocked. I have no clue what would cause it to do this.

I'm curious to learn what caused this before rebuilding to try and make sure it doesn't happen again. I have sent all this info to XA people and have not heard anything...

In the blackbox file - I see the voltage seems fine throughout the flight, I see that motor #4 goes to 99% all of a sudden. Everything on the quad was tuned up great, motors balanced, props, new stock ESC's and motors. Motor power looks good throughout the flight.

Also note the VERY low vibrations even with all the fast aggressive flying. So everything was working great. Well apparently not...haha!

Only thing I can think of is maybe that the #1 arm had "weakened" over time, and just got to its limit and snapped under pressure?... But that seems odd seeing it wasn't under load at the time of the crash. It was just hoovering there. Granted both of the 2 flights in the black box log were fast and had some aggressive maneuvers ie. hard stops, full forward flight, rocking back and forth, high speeds(see fastest speed).

Very strange.....
 
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VIQuad

VIQuad

Member
Yeah you may be right about the ESC.

XA seems to think that motor #4 died and caused it to crash. Seeing it shot up to 99%.

Good thing it happened 3ft off the ground and not 100ft high, over over someone's property.

I think I'll replace the ESC and motor #4 then rebuild.
 


VIQuad

VIQuad

Member
I'll check but its just the stock T-Motor for the X650 Pro . It doesnt have much fly time on it, maybe an hour, so if it was the motor that's even more surprising.
 

Z

Zirt57

Member
What I meant was any of the wire connectors to the ESC/motor etc that have anything to do with #4 motor. Being new, it is still man made and even the factory could create a bad solder joint. A sudden drop like that usually means something shut down. Now all you have to do is find out why. At least you know, because of the blackbox, which motor/esc combination to check.

Jeff
 


D

Dhardjono

Member
Well let me put my experience with crashes, I did have 1 of the bullet connector just came of while i was flying and went down it was cruising at 10 mile an hour after the crash i saw the bullet with the wire came loose. Not sure if that your problem but i solder all my motor to the esc direct ly now no more bullet connector they get loose too after couple of flights. But that looks more like super x having an issue but no one here in this forum will blame super x for any fault usually it's the motor or the esc or pilot error super x is not super perfect that just my opinion. I had an experience with 1 esc going bad it would woble or will not work at all this was on my arris 650.
 
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VIQuad

VIQuad

Member
XA looked at it and told me they think that motor #4 died.

I know that stuff happens, but just seemed odd to me seeing that the motor was very new and the ESC as well was new, maybe both had been flown on a total of 10 packs.

I plan to replace motor 4 and the #4 ESC, then rebuild and test. Might test all my other motors and ESC's as well before the rebuild.

But quite frankly I think I might try a QAV400 with a gimbal build next instead of keep pouring money into the 650 Pro.

I don't know we'll see.
 

D

Dhardjono

Member
VIQuad said:
XA looked at it and told me they think that motor #4 died.

I know that stuff happens, but just seemed odd to me seeing that the motor was very new and the ESC as well was new, maybe both had been flown on a total of 10 packs.

I plan to replace motor 4 and the #4 ESC, then rebuild and test. Might test all my other motors and ESC's as well before the rebuild.

So you test the motor and did not power up? with the esc.
Click to expand...
 


VIQuad

VIQuad

Member
Ok just tested all the motors and ESC's like showed in the video posted above. And all of them seem to be fine. Spin fine start up and stop fine, no weird noises or stops. All "beep" correctly as well when powered up.

So what are the signs of a bad ESC? what should it do or not do, any tell tell signs?....

Same goes for a bad motor?...would it not spin up? would it shutter? what are the symptoms?....

I now doubt I need a new motor or ESC, these seem fine.

Testing motor#4 and ESC video -

 
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D

Dhardjono

Member
VIQUAD you smell any burnt smell let me tell you my tiger motor with naza went into fail safe i had to walk to get it took me 3 mins and it was spinning full throttle upside down chopping the grass at the same time that motor got hot red hot smell burnt and still running using it on my qav 400 now. Your video esc look good and motor it some time the superx i know people will hang me on this site. Today i just came back from flying my 650 it sudenly lurch forward when i gave 50 percent throttle and flip over , Than i started again it was fine. Like this one
this one went back there was no recorded on black box .After this i recalibrate compass.
 
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VIQuad

VIQuad

Member
Yeah sounds really strange.

I think my motors and ESC's are fine. I'm going to rebuild it and test it, I'd be willing to bet its fine.
I'm thinking the arm was just weak and snapped under load and caused the crash. Everything else seems fine, to me anyways...

But I still would like to know what to look or listen for on a bad ESC or motor.
 

D

Dhardjono

Member
well it would wobble on the side of the bad esc or not work at all i wonder if i have some footage on vimeo with my arris 650 that had a bad esc let me look
 


VIQuad

VIQuad

Member
Yeah that's what I was thinking too.

I guess it if the ESC was bad it would work at all? ....and same for the motor.
 

Old Man

Old Man

Active Member
Regarding solder joints.

In full scale aviation solder joints are forbidden for flight critical control functions. So are electrical zip ties since they are noted for cutting wire over time, especially when applied too tight. Everything electrical is connected using mechanical and crimp fasteners. Solder joints are subject to vibration cracking. Soldered wires introduce a failure point that weakens every time a wire is deflected from its neutral position. Our power distribution boards are little more than disasters waiting for the time and place to come apart and fail. Bullet connectors are no salvation since they use a solder joint. Flat soldered wire connections on PDB's should scare you every time you make one up or look at one.

If there's any reasonably talented and creative EE/ME out there reading this I'm sure a vastly superior electrical system could be created for our aircraft with little effort.
 

Av8Chuck

Av8Chuck

Member
Old Man said:
Regarding solder joints.

In full scale aviation solder joints are forbidden for flight critical control functions. So are electrical zip ties since they are noted for cutting wire over time, especially when applied too tight. Everything electrical is connected using mechanical and crimp fasteners. Solder joints are subject to vibration cracking. Soldered wires introduce a failure point that weakens every time a wire is deflected from its neutral position. Our power distribution boards are little more than disasters waiting for the time and place to come apart and fail. Bullet connectors are no salvation since they use a solder joint. Flat soldered wire connections on PDB's should scare you every time you make one up or look at one.

If there's any reasonably talented and creative EE/ME out there reading this I'm sure a vastly superior electrical system could be created for our aircraft with little effort.
Click to expand...

Wouldn't that be nice.

VIQuad said:
Yeah sounds really strange.

I think my motors and ESC's are fine. I'm going to rebuild it and test it, I'd be willing to bet its fine.
I'm thinking the arm was just weak and snapped under load and caused the crash. Everything else seems fine, to me anyways...

But I still would like to know what to look or listen for on a bad ESC or motor.
Click to expand...

It seems odd to me that the arm would break while it was hovering, didn't seem to be much of a load on it to cause it to break. Something you need to be careful with is that sometimes a solder joint can fail or short for a very short amount of time, when it does the controller compensates so an increased amount of current starts running through the ESC on its way to the motor. After plugging everything back in to test it, it might appear to be OK but the only sure way to know is to open up both the ESC and the motor to visually check to see if anything inside the ESC is burnt or any of the insulation on any of the winding is melted. It might not look burnt, just a little milky looking, if it is then you need to measure the inductance to make sure the windings are OK.
 

VIQuad

VIQuad

Member
Yes, I agree.

Only reason I was saying the arm might have snapped is because, the day before this flight I had the props on wrong. And tried to take off and the quad flipped over to that side, and landed, what I thought was sorta hard. Perhaps that flip on that arm might have weakened it or it might have cracked it...? And hince the next day this happened?...maybe it was the straw that broke the camels back. :)
 

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