Help me with forensics

[moodman]

I just crashed my TH. 3 broken arms, broken leg, and broken camera. Body still works. Wanna buy it?
Anyway, I have no idea why it crashed. It suddenly started doing weird stuff as it was hovering, then made a beeline for the ground at high speed. I have the video footage from my st16 up to the moment of impact and can't see anything that would clue me in on what happened.
I do have flight logs on the st16, but don't know how I can interpret them to determine the cause of the crash. I need to know if it was something I did, or a fault in electronic.
Does anyone here have experience in forensically determining what might have happened? I don't want to repeat this on my other two remaining TH's. I haven't decided whether to repair it, sell it for parts, cut my losses, and/or buy another one.
I'm open for advice. Thanks.

 

[Mrgs1]

Best to post them on here, you will get a constructive reply.

How to Download Telemetry and Video from ST16?

Hello...I would like to download the Telemetry and the Video Recording from the ST16. Some know how to do this?

yuneecpilots.com

 

[moodman]

I would, but don't know which files to post!

 

[DoomMeister]

I would, but don't know which files to post!

Give me a few minutes and I’ll send instructions. The old ones only give the telemetry and we really need all of the flight data so we can see the controller inputs.

 

[DoomMeister]

Retrieving flight data from the ST-16.

Insert an SD card in the ST-16.

Power up and enter Pad mode and tap OK.

Enter menu by pressing circle with six dots.

Select File Manager and scroll to the FlightLog folder, then tap arrow at the right of FlightLog folder.

Now select Compress and add the date to the file name suggested.

Scroll to bottom and find the zip file you just created, tap the arrow at the right and select Copy.

At top left tap the icon that looks like two SD cards to swap to the SD card inserted in the first step.

You will then see the file structure on the SD card, select Paste at the bottom to add the file you just copied.

Now press the ‘Back arrow’ at bottom right of the screen to exit File Manager and select Settings.

Tap on Storage, scroll down to SD CARD and select Unmount. Press the Home icon and power off the ST-16.

Remove the SD card and use your PC to upload the zip file here by using the Attach files button below the Reply box.

 

[moodman]

Retrieving flight data from the ST-16.

Insert an SD card in the ST-16.

Power up and enter Pad mode and tap OK.

Enter menu by pressing circle with six dots.

Select File Manager and scroll to the FlightLog folder, then tap arrow at the right of FlightLog folder.

Now select Compress and add the date to the file name suggested.

Scroll to bottom and find the zip file you just created, tap the arrow at the right and select Copy.

At top left tap the icon that looks like two SD cards to swap to the SD card inserted in the first step.

You will then see the file structure on the SD card, select Paste at the bottom to add the file you just copied.

Now press the ‘Back arrow’ at bottom right of the screen to exit File Manager and select Settings.

Tap on Storage, scroll down to SD CARD and select Unmount. Press the Home icon and power off the ST-16.

Remove the SD card and use your PC to upload the zip file here by using the Attach files button below the Reply box.

Thank you Eagle's Eye. I have done as you instructed and the zip file is attached. The flight took place on Mar 27 and lasted for 3:03 minutes. There is a video in my gallery, but the video is corrupted on the drone itself because...it crashed!
Anyway, if you can make sense of these log files, I would appreciate some help in figuring out what might have gone wrong. I think everyone here can perhaps benefit from my misfortune.
Can't wait to hear what you might find!

 

[Ty Pilot]

I just took a quick look at the flight from the 27th of March. The first thing I noticed is that you went from 16.6 volts at start up to first battery warning (14.3) in a little over two and a half minutes so, either it was very cold or you have a failing battery or both. However, this was not the cause of the crash.

For the first couple of minutes everything was fine then, as you neared the first battery warning, you began getting compass errors while over the center of the field at around 60 feet. About seven seconds after the first low voltage warning the telemetry shows motor #3 off (five rotor mode engaged) and a split second later you hit RTH and this is when the craft was descending rapidly to the ground.

Hopefully others can take a look at this and see what they think. I do not know if perhaps you encountered a flying object such as a small bird that knocked out a motor perhaps and this all at a time when you are very low on power. But being in five rotor mode with no power reserves did not help. Perhaps it was truly a motor failure or something else - very strange.

 

[moodman]

Thank you Ty Pilot. This wasn't a particularly long flight. I have watched the video that my ST16 stored, and it seems glitchy, as though there is some kind of telemetry dropouts. The drone wasn't that far away from me. I could hear its motors beginning to act up. It was as though the motors were trying to compensate for something. Did it stay in 5 motor mode after it began, or was that just a short duration mode change? I don't remember getting that warning message on my drone.

I tried to bring it in with RTH, but it just went its own way at a 45 degree angle to the ground at high speed. Maybe I should have stayed in angle mode...

Its possible a blade broke in flight, as I tried to recover all the bits and pieces, but never found all the prop parts. Could have been that one part of a blade broke off in flight making it unbalanced.

Would compass errors account for this kind of behavior? Also strange that the battery would give out after such a short flight. But, I will check the LiPo balances and see if there is any bad battery indication. I just need reliability and predictability.

Thank you again. This at least makes me feel better that it wasn't anything I did as a pilot.

 

[Ty Pilot]

Other than the rapid battery drop, the flight appears 'normal' for the first two and a half minutes, but as I mentioned the battery was quickly arriving at the 'Get on the ground' point for most H Owners. At the end of the flight things happened very quickly and here is a breakdown:

15:16:00 ................Take off and normal flight

---------------------------------------------------------------------------------------------------------------------

15:19:00.................First Compass Warning - 14.6 Volts - 60 Feet Altitude

15:19:03.................Low Battery Warning #1 - 14.3 Volts

15:19:07.................Low Battery + Compass Warning #1

15:19:09.................Low Battery + Compass Warning #2 - 14.2 Volts

15:19:10................Motor Status 251 - (5 Rotor Mode) - Motor 3 out

15:19:11................RTH Selected with resultant crash

So in the last 11 seconds everything happened one right after the other. If I am reading this right, I am guessing you had a prop separation for an unknown reason, upon seeing this and after holding a vibrating controller for nearly eleven seconds you switched into RTH which may have throttled up in an attempt to obtain the RTH Height but with the battery dangerously low the craft lost control and crashed.

In a normal flight you want to be on the ground; at or before 14.6 volts for just this type of situation. Not saying this was your fault but it maybe could have been avoided IF the voltage had been noted as dropping as rapidly as it did. This doesn't account for the compass warnings at altitude nor does it tell us why the number three motor was cut, both of which may have been factors. We know five rotor mode works, but couple with the low battery I don't think it had a chance.

 

[moodman]

Well, at least I THINK I didn't do anything wrong. I do monitor battery, but normally that battery warning should not have happened so early in the flight. Motor #3 might have been the motor that lost the prop.

You should work for NTSB

THanks so much.

 

[Ty Pilot]

You're welcome, and I hope you didn't take what I said wrong, just pointing out all that I saw. Like a lot of accidents this may be the classic type that has a bunch of little things happening in a series and all it took was one little link (like the motor or prop failure) to complete the chain. Sorry for your loss hope you get it fixed up and back in the air.

 

[moodman]

NO offense taken at all. As a matter of fact, I welcomed your analysis.