I had a crash yesterday from about 60m. The Y6 is not looking good. I can fix it up, but I can't figure out why it crashed.
I have dataflash logs and FPV video from the flight. The FPV camera has seen better days - the footage is blurry, but it's enough to give you an idea of what went on.
The flight lasted just over a minute. The craft ascends slowly in Alt Hold above some nearby trees. Things look a little shakey around 50s in, and there was no wind of which to speak at the time. I start flying it away from me while turning it away from a nearby river just to be safe (glad I did).
Then the craft suddenly loses all attitude control and does a spinning nosedive into a branch. The craft then tumbles the remaining 20m or so to the ground. The branch must have caught the battery cable, because I lost video and logs at that point, and the battery cable was disconnected when I got to the crash site.
When I picked it up, several of the motors felt quite hot to the touch. I often touch-check my motor temperatures after flight, and these were warmer than usual. Prior to this flight, I did an 8-minute hover test to see how these new props worked, and I noticed the craft was drawing ~40A at hover on a couple of 3S batteries. Last time I flew it was drawing ~25A-30A at hover on the same batteries. This was the only clue that something may have been amiss before the fatal flight, but I thought it was just the larger, cheap props. I thought I'd have a fly and see how they did.
Looking at the logs, it is clear that around row 1960 the ATT inputs and actual ATT values start to diverge. The Roll field is pretty neat as the craft spirals to its doom - the Roll graph looks like the sound wave of a struck bell.
There are no clear ERR logs in here that I can see, but I can't seem to figure out how to filter on columns in APM planner, so I can't be sure I didn't just miss one. There are a number of errors in the log itself - missing values in some rows, and row types that make no sense like "A8.94".
Originally I thought motor failure, but after a test here hours later all my motors spin. A couple are making bad noises, but that could be an effect of the crash, and not a cause. Is temporary motor failure a possibility, induced by temperature or something else?
Can someone with some experience tell me what went wrong, as well as how they diagnosed it? Any help is greatly appreciated.
Specs: 3DR Y6B, APM 2.6, ArduCopter 3.1.5, Gemfan plastic 12x4.5 props, Tiger 6000mah 4S battery from 3DR, 3DR telemetry and FPV, jDrones 880Kv motors.
Logs attached. FPV video here: http://youtu.be/SSrp0An6prs
(Originally posted in the wrong place - deleted the original)
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