Hi All,

I've been doing lots of research on here and other sites trying to find out what might of happened to cause crash a week ago.


Bit of background,

  • APM2.5 running v2.70 arduplane. 
  • Power to APM via 3DR power module, and Turnigy UBEC 3A powering servos.
  • Ubloc GPS, 3DR telemetry 433mhz radio link.
  • TX/RX Hitex Aurora 9. 
  • FPV 12v camera and 5.8ghz video tx
  • Plane EPP FPV , 4S 5000mah Zippy flight battery, powering everything on board.

The day in question I had been flying around in manual, stablize and FBW-A all perfectly fine, probably could do some work on the PIDs, but flys perfectly ok.

Had used RTL, Loiter, Auto successfully, 

Landed, recharged batteries and went again with a different mission, slightly different positions on the misson and slightly higher altitude. 

Went round the mission fine, so whilst in loiter I sent a "restart mission" command and set it off again. Had a little trouble hitting home position so "nudged" it over home. and away it went to wp1 as shown on the HUD on laptop. 

Every thing was going fine until almost reaching a wp at which point the plane entered a spiral dive and had no control over the plane from the remote, Can confirm that the position the plane was in and where i was standing has never entered fail safe on any flight (prob 50-60 flights), so I do not believe i was out of range although I don't have rssi signal from tx/rx..

Now i've been looking at the logs, both downloaded from APM and the tlog saved during the flight and from what I can tell the tlog stopped just before the plane went into its death dive. 

Would this indicate there was a problem and APM was trying a reboot?

FPV continued transmitting all the way until impact point, at which point battery was ejected and disconnected. It seems the tlog stops about 5-6 seconds before impact point.

Now not sure what to check next, or really what the tlog data is showing me, consider myself still a noob, even after few months of reading as much as i can and reading the code to try and get a grip on how its working. Programmed several ardunio projects so know the basics.

If anyone can take a look and give any advice I would be grateful. The one thing I did notice on this tlog compared to others is the Vcc, which looks strange. On all other logs i can see steady voltage +/- 0.1 volt from around 5.2 to 5.1v.

Thanks, as the plane has now been repaired and almost ready to go back in the air, I want to make sure  this wasnt stupid user error or a fault that could happen again. 

Thanks in advance.....

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Also the plane orientation a few seconds before the problem seems to be way off , almost looks like the plane is flying backwards.....

But no idea what is happening there?

-Sorry, i can't open your flight logs, but a spin sounds a lot like lack of forward airspeed, versus groundspeed, and recovery at the crucial moment that it's required needs lots of power with opposite rudder then elevator once the spin becomes a circular dive, Unless you have tested the FC ability to recover a deep stall (with plenty of altitude to take back control if it fails) it may have been a gust of wind from the rear, if you enter a turn at that time, a stall becomes even more feasible, Your normal safe airspeed envelope between cruise and stalled in certain situations can also be narrowed with a change in wind direction, influenced by terrain etc, your headwind can become a tailwind with a 90 degree turn at the wrong place, and plus 15kph breeze becoming minus 15kph breeze subtracts 30kph from your cruise speed and a wing can drop in a second. The other thing with autopilots in a stall situation is, they usually only try to maintain heading, again during a spin, this will not hold rudder against the rotation. I will only allow autopilot to maintain airspeed (pitot) during missions, not GPS (groundspeed) for this reason. Sorry to hear about your loss though.

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