A couple days ago, my 3DR Y6 suffered a failure mid-flight. I maintained altitude and some control for a few seconds, then, with the throttle at 100% is began losing altitude until it crashed pretty spectacularly into a tree and fell from about 20m.
Turns out one of the motors had died. I did a motors test with APM Planner and 5 motors turned but one did not. These are jDrones 880Kv.
I looked at the power system - PDB connection, ESC, connectors, wires into the motor, and everything looked fine. I looked closely at the motor with a flashlight, and noticed that there seemed to be a bit of a jumble of copper wire near the base of the motor, visible through the ovular openings in the black base.
I took the motor apart, and saw this:
The ring of wire bundles slid easily up from the base, which I don't think is supposed to happen, as this was not the case with a healthy motor I opened up. There appears to be some loose copper in there, and two copper wires appear cut - the ends stick out from some black rubber housing by a few mm, and go nowhere.
Can I fix this motor, or is it time to buy a new one? Seems a shame to throw it out if it's just some out-of-place copper.
Replies
Personally, I would replace the motor.
The cost of the new motor vs another crash with unknown $'s damage.
Depending on your soldering skills, the enamel coating on the wires will more than likely melt when you repair and you might end up with more shorted turns.
Thanks Scott. I will replace the motor, and order a second.
This failure happened at 30m or so after 20 minutes of normal flight. I'm assuming I did a bit of damage on a previous crash that didn't manifest as a failure until after some time had passed.
Is there a way to see this sort of failure coming? For example, I configured APM to spin the motors "very slowly" when armed, and when the drone was new, all motors spun slowly when armed. Now, however, some motors spin and some don't. As I slowly increase the throttle before takeoff each motor starts spinning at a slightly different point. Is this a sign that more of my motors are going to experience catastrophic failure?
After about 20 minutes of flight?
It would seem that your battery going flat was probably the cause of not holding altitude and crashing.
What battery are you running?
What voltage do you have fail safes set to?
Well, about 20 total, but I flew for a while on one battery, then swapped in a couple more. I was on two parallel 3300mah 3Ses when the crash occurred and the OSD said my wiltage was above 11.
You can also see a neat sudden pitch forward just before the crash in the FPV video that looked to me like a sudden change in thrust from different motors that APM reacted to shortly after. I'll post it tonight or tomorrow in case someone wants to have a look.
The numbers from the APM battery monitor look sensible, so I think it's correctly configured, but there's always the possibility that it's not.