APM 2.6 Brownout

Yesterday, I updated my apm 2.6 and calibrated the board. When I was flying, it seemed to work well in stabilize, so i switched to althold then to poshold and all was well. Then I went to test rtl ( I had a GPS lock) that’s when all hell broke loose, it seemed to climb like normal then it just lost power and started to fall, luckily I was able to recover it and land safely. I believe the problem is that the board experienced a brownout. I have the apm powered via a power module, and I was wondering if someone could look at my log (which I have uploaded) and give me some more details on what happened, because I don’t quite understand the log very well. Any help is appreciated and thank you in advance!!

2016-07-30 19-57-15.bin (230.0 KB)

Your Vcc is between 4.8v and 5v which is not a good fluctuation but should be fine and indicates no brownout.
You triggered RTL with channel 8 but it did not immediately respond, is this correct?
You have an un-commanded roll and pitch at about 4700 in the log, could there be a hardware issue?
Have a look at ATT/Roll and ATT/DesRoll and also ATT/Pitch and ATT/DesPitch.
You also seem to have pitch oscillation between 5500 and 6000, again, is there a hardware issue?
Also I see no battery monitoring. Do you have a battery monitor installed?
Have you logged your IMU data to check vibrations? Just asking.

The RTL function seemed to respond when I flicked the switch and that’s when it went crazy. I do have the fence setup and it appeared that the fail safe was triggered.

I don’t think there is a hardware problem, all of my hardware is new. The motors pull around 15amps at full throttle my pdb is rated for 120amp, 30amp ESC’s, and the battery is a 2450mah 4s lipo 30-40c so it should be able to handle the load, and it was by no means depleted when I got it back. As for the battery monitor I have one I just forgot to set it up again.

Is it possible that this was caused by vibration? The mount I have the board on doesn’t seem to cancel them very well, I’m waiting on a new one. However there shouldn’t be to much vibration all of the props are balanced. Thank you!!

A hardware problem could be anything from a loose prop to intermittent bullet connectors.
The uncommanded roll and pitch is indication that something happened, hit by a bird?? dunno, something happened though to produce it and it was followed up with oscillations shortly after. My best guess would be a slipping prop.

I doubt whether it would be caused by vibration as you would immediately notice erratic height variations as soon as you switched to AltHold mode. Simplest way to tell is log IMU data for one flight and look at it.

Did you take off before you had a GPS lock?

Thank you, I’ll make sure to check all the props and connections. I have enabled IMU logging and am now just waiting for my batteries to charge then will go take a flight. Once again thank you!!