Hi Arduplane Users,

Seeking some help if anyone has experienced this problem before with their APM.

We are currently using APM 2.5 on a Skywalker 1880. Its flashed with 2.40 firmware as we had some custom code changes to trigger camera and also log headings.

Th problem seems to happen randomly..we can fly the plane for like a total of 100km distance traveled in total at a crash will happen on the 101km..or it can happen on the very first mission. Initially we thought it was a mechanical failure but since most of the time we are like 2-3km away from where the crashed happened we couldnt really determine. But recently we are closer to where the plane is flying and this is what it will do:

1) As its banking or on a straight path..throttles up to almost full

2) Dives straight to the ground.

3)Any attempts to switch to stabilize and manual is not possible

All this happened only in Auto mode except one occasion in stabilize it dived but we had the airspeed sensor on for that incident so that may have caused it. Other than that the airspeed was not enabled.

I have some logs but im not sure it will be helpful as we only log certain parameters and at 4 secs apart.

Some of my setup info:

Plane: Skywalker 1880

APM: APM 2.5 with UBlox GPS Lea 6 & 3DR 433MHZ Telem Set

Motor: OS Motor OMA3820-1200/Turnigy G10 1200 KV

ESC : Tahmazo 60A/Turnigy 60 A (Red wire is disconnected as we use seperate BEC)

Servos: 4 X Emax ES08MA

Tx & RX: Futaba 12FG with 7 chn RX / JR 9303 with AR7000

UBEC: Hobbywing 5a, MAX 7.5A switching at 5V

Battery: 2 x 14.8v 3300mAH parralled to ESC and Balancer connected to BEC to supply 5v to APM

Others: PRISM IR Trigerring device, Airspeed Sensor(disabled after one of the crashes as we suspected it may have contributed)

We are migrating to the 2.67 code after successfully porting our custom codes as we felt that all the crashes exhibit the same behaviour and may be down to some bugs in the 2.4 firmware. But we just want to make sure that its not any of of the other electronics .

I could post the TLogs or onboard logs when i get the data from my work laptop tommorrow. These crashes are driving us nuts as we thought we solve the problem and happens again after a while.

Any comments and suggestions would be much appreciated.

Cheers and have a good weekend,


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That's very old and many bugs have been fixed since that version. Hard to say which of those was causing your issues but glad you're updating to 2.67, which is solid. 

Thanks Chris.. We are moving as soon as this week but we will test for at least 200km distance flown in total and hope that this issue doesn''t happen again.

Really perplexed.

1. remove any user code for test. user code may stop cpu

2. Use two separate supplies, one for the servo and other powerful transmitters, another for the autopilot. otherwise the voltage brownout due to congestion servo often leads to failure of autopilot. APM 2.5 requires a stabilized power supply 5volt + -5%

3.ardupilot take care of humidity, even mist condensed in some places (circuit quartz resonator) can lead to a shutdown of the processor.(I cover these areas protective paint)

I had a very similar problem but thought that it was either my Tx or Rx since I was only flying around LOS in manual mode.

I was flying a Skywalker with a 2.0 board and randomly it would throttle up, turn and dive!  It made it fairly scary walking up to the plane to disconnect the battery.

This all occurred a couple of months ago so I cannot even be sure that I was using 2.40 now.

To remedy this problem I sent my radio into Futaba to get checked out, replaced my Rx, and upgraded my code.  I decided to send my radio in because I had purchased it used and had no idea if the previous owner had taken care of it or if they had abused it in some way. :)

I have upgraded to the 2.67 firmware now and haven't experienced any problems with my flights.


Hi Khairul

I've had a very similar experience, it would crop up every now and then. See this vid: https://www.youtube.com/watch?v=17GaSx7UbJY

Thinking back, it could very well have been 2.4 as well.

It would happen mostly when the APM was on for a while, it would just go nuts, even in Stabilize - so maybe it's not exactly what you're seeing - I could switch modes while it's trying to kill itself.

I hope you're problems disappear with 2.67. I know all about celebrating solving a problem only to have it re-appear.

Can I go slightly off topic, how the heck do you get 200km on one flight with a Skywalker??

Thanks for the input Mike. 

It is the same characteristic as my crashes..randomly powering up and dive.

We had calibration issue with our Futaba 12FG so it was sent in..so we thought that was the cause. but even on my JR9303 the issues still happened after taking all the precautions we can and after the 5th crash we were quite sure it was not anything else other than the firmware.

We'll upgrade to 2,67 and will keep this updated. Hopefullly we cross 200km of flying without any issues.

Hi Hein,

Looks exactly the same as what i have experiened..hard bank left throttle and dive.

Well probably it did change mode but the speed at which it was diving was too much for me to save it in time.

About 200km, its not in one flight, what i meant is the total distance one airframe have flown. We do mapping so, our flights normally cover total of 20km on average. But linear distance is just about 2-3km .

Btw do you still experience this issues?

Thanks for the input!

Hi Alexey,

Thanks for the suggestions.

We will do all of those in the coming days.

For powering the APM separately im thinking of using another 3A 5v BEC and a 7.4v 1000mAH batt to it. Should be enough for 1.5 hrs flight?



Ah I see ! I only assumed, because my problem went away as soon as a recycle the APM.

I have a discussion on my exact problem here http://www.diydrones.com/forum/topics/arduplane-convinced-of-doing-...

You say that sometimes it would happen right after launch? Would that be after a cold start too? My problem appeared after landing, not turning off the APM, and taking off again after 10 minutes. I caught it once going nuts while on the ground still - the APM planner would show it do constant loops and the ailerons would react, except, it was level on the ground..

I haven't experienced the problem since and I've done many flights. I'm pretty sure, in my case, it's a bug that went away. Hope it's your experience as well.

Hi Hein,

Great to hear that you have not experienced it anymore. Some encouragement for us then.

Oh our problems didn't happen after launch  apologies if it seemed that i meant that. It would happen like halfway through an Auto mission, or while turning to a way point navigating to next way point or returning to home.

We'll be crossing our fingers for our next tests. :-)



To further troubleshoot my problems I removed my APM from my Skywalker and placed it in my Sky Surfer.  The SS is a cheaper airframe and isn't loaded down with the FPV equipment that I thought might have been producing some interference for the APM and, of course, I didn't want to crash my Sky Walker with all of my expensive electronics on it. :)

I'm still troubleshooting here but it appears as though the problem has gone away.  I'm still on my backup Tx, using my Sky Surfer, but on current firmware for my APM 2.0.  Yesterday I was messing around with my RTL settings and was pleased to see that it was working pretty well.  No throttle increases or dives for the ground that didn't quickly level out once the target altitude was reached.

I should mention that when I purchased my APM 2 that I bought it with the GPS onboard and not remote.  I don't know if that has anything to do with it though since I was pretty darn sure that I was flying around in manual.

Good luck with your tests! :)


I have exactly the same problem last week with APM2.5 on a Skywalker 1.8m (black).

Took off on manual, checked stabilise mode OK, then switched to Auto. The plane immediately powered up, banked and dived. I switched to manual mode but no responses to any controls. It went it vertical from 300ft and make a 6" hole in the ground. The recovered motor was very hot.

I have to say I flown this configuration for about 15 flights. This is the second time it did an uncontrollable dive. The first time was repairable because it dived into mud. This time the plane was totaled.



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