My HEX crashed from a FAILSAFE / DISARM event in mid flight!

I have been successfully flying Quads & Hex's with previous firmware versions of Arducopter using APM 2.5 boards until Saturday afternoon's unexpected crash. For a long time I have been using 2.8 and then successfully migrated to 2.9.1b, after having to tighten up more on eliminating vibrations.

All functions ran fine on my Hex under 2.8 and 2.9.1b.  It is an FPVPilot aluminum frame, using RCTimer 880kv motors/ 30a ESC's, minimosd, apm2.5, mavlink, and fpv cam/550watt 5.8 transmitter.  I use a turnight 9x with the Dragonlink for flight control.

On Friday, I upgraded the APM firmware (after factory reset, erase) to 3.0 rc5, after my friend Francis had good experiences with 3.0 rc5 with his tricopter.  The only issue he was having was the toilet bowl effect from which some recent posting, Randy was able to help him with the Compass MOTor configuration process.  In any case, I did some minimal testing on 3.0 rc5 after updating and all functions seemed fine... Stabalize, Alt Hold, Loiter, etc...  in some pretty windy conditions.

On Saturday, Francis and I went out to the field to test mission planner.  The only thing I changed from the day before was I turned on FAILSAFE for RSSI and Battery.  I tested this on the bench, as advised, by powering on/off the dragonlink and watched the mission planner radio values, etc.

At the field, I began by flying LOS at first as usual before flipping to FPV.  At this point I  flying our a little further (less than 1/2 mile max...   and a little higher  (no more than about 50 ft).

After a few minutes into the FPV portion of the flight, motors stopped and it dropped to the ground.

I've attached a number of screenshots and the log file.  As you may see from the attached logs, that after a long DISARM state, I ARMED, then flew all around for quite a bit and then at around the 868 time mark at about 30 feet up (we were on a top of a hill flying out over a valley producing negative Altitudes at points) it dropped like a rock!.

After locating the crashed HEX, the APM was still in a DISARM state.

After playing the logs at a slow rate, I saw that for some reason in flight, a FAILSAFE occurred with an immediate DISARM (as if my throttle was at 0).  The battery was still strong.  I looked at the graph for throttle af the time the FAILSAFE occurred, just to make sure that in my frantic, I didn't lower the throttle to 0, and as you would expect I acutually maxed it trying to recover in some way.

I've checked everthing on the HEX and it doesn't appear to be electrical.

Since the crash on last Saturday, and reading about others who have had disarms in mid flight, I decided to go back to 2.9.1b, test for a while with "NO FAILSAFE", and see if the problem occurs again.  So far, with only minor testing around the house (not at the field) it appears to be okay.

I am very afraid that this will happen again and hate to have to go through all the repairs again.  I also would like to migrate to 3.0 fater the final release.

Even though I have not seen anybody else posting this type of severe issue with 3.0, could you review my log and help me to determine where the real problem may reside.  I am a novice at reading the logs but eager to learn.

In the meantime, I'll try to do some more robost testing with 2.9.1b with no FAILSAFE, just to get a "good feeling" baseline again...  hopefully.

If I should have the same issue again, and if before I get your advice, I'll fall back to 2.8 (where I have flown with this same HEX successfuly quite a bit).







Thanks a lot,

Mike Governale

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  • Developer

    Do you have a dataflash log by any chance?  dataflash logs show the failsafe and errors info better.

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