In flight failure

[Steve Carr]

I called Yuneec to alert them to a flawed firmware update. They said it was impossible and that I pressed B1 which shut down the motors. They refused to look at the telemetry which clearly showed the problem. The failure occurred on final descent with yaw to the right at the same time. It dropped 180'.

So tonight I took the same controller and connected it to the flight simulator and did a quick test flight using the same control method. It did exactly the same thing every time I tried it.

Sooooo.........Yuneec........B1 was not pressed. Nope. I'm giving you a fail on CS for this one. And, oh, by the way, exactly the same thing just happened to another experience H pilot. And I confirmed it in his flight logs.

The ST16 firmware version number is V3.01.b30

To check your ST16 to see if it has a problem open Channel Settings. The opening screen should look like this:


If it looks like this then don't fly. You have a problem:

 

[Tuna]

So in the telemetry, are you seeing the thrust channel dropping to zero when you do that stick movement? I believe it's meant to stay above 180 or somewhere like that even when in full descent. Motor off is signalled to the Typhoon by that channel going to zero for a few seconds.

As far as I can tell this is either a rate issue (there's a point in the rate curve that inexplicably gives zero for certain non-zero input) or a mechanical issue (the stick is going to zero when it shouldn't).

 

[Steve Carr]

I believe it's meant to stay above 180

The minimum value for the throttle is around 660. On this controller it is 662. It drops to zero when B1 is pressed.
After the firmware update the yaw channel was added to the throttle channel. This forced the value to keep dropping below 662 until it was low enough to initiate shut down.

 

[Steve Carr]

I created a history for that controller before and after the update. Prior to the update the minimum was always 662. After the update there were occasions where it dropped below 662. On the final flight I was adding yaw while descending. I rarely do so. This was the fatal maneuver which lasted long enough to compete the shutdown.
This shows the values of the Throttle Channel during that descent. It should not have gone below 662.
747
624
549
584
522
476
411
397
371
338
278
209
180
144
89
73
92
88
0

 

[Steve Carr]

This is the landing sequence portion of the remote log for that controller. Remove the .txt to open with Excel.

 

[Mickeyboo]

Thanks very much for this post Steve. Just to clarify this only happens with latest firmware update? Trying to remember how and if you can load older firmware. Could someone please remind me if this is possible and how that is done? I still have older versions of the firmware.

 

[Steve Carr]

Thanks very much for this post Steve. Just to clarify this only happens with latest firmware update? Trying to remember how and if you can load older firmware. Could someone please remind me if this is possible and how that is done? I still have older versions of the firmware.

It has only happened to me on one ST16 with this firmware. I know of at least 2 others that experienced the same issue as well. So I believe this to be a rare anomaly with the firmware update.
It is a fairly easy issue to identify had I known of the potential. Simply having a background chart of the Channel Settings and doing a quick comparison would reveal the fault immediately. You only need to know what to look for.

 

[glider]

Oh my. I routinely yaw while coming in to land, surprised it hasn't crashed yet based on your information. This is an extreme point of failure and something Yuneec should immediately address, including publishing a PSA on their webpage. They'd better not pull a DJI.

 

[glider]

It has only happened to me on one ST16 with this firmware. I know of at least 2 others that experienced the same issue as well. So I believe this to be a rare anomaly with the firmware update.
It is a fairly easy issue to identify had I known of the potential. Simply having a background chart of the Channel Settings and doing a quick comparison would reveal the fault immediately. You only need to know what to look for.

Do you have an early model controller or newer? I wonder if it only affects certain ones.

 

[Tuna]

One check would be to see if reverting the firmware removes the problem. Another would be to take a new controller and see if you can accurately reproduce the problem on that one.

Excellent detective work though!

 

[Steve Carr]

I wonder if it only affects certain ones

The two from which I have been able to review the logs were bought 6/16. I am not aware of any changes that were made to the ST16.

 

[Steve Carr]

One check would be to see if reverting the firmware removes the problem. Another would be to take a new controller and see if you can accurately reproduce the problem on that one. Excellent detective work though!

I know how to revert the H but not the ST16. I believe a factory reset will correct the problem. I have not done so with this controller. I can manually fix the channel settings which I have done with later flights but when I create a new model the error is carried over.

 

[Steve Carr]

I routinely yaw while coming in to land, surprised it hasn't crashed yet

If your controller had this glitch you probably would have already crashed. The other flight log I reviewed had J3 mixed with J1 so his crashed while flying forward.

 

[glider]

If your controller had this glitch you probably would have already crashed. The other flight log I reviewed had J3 mixed with J1 so his crashed while flying forward.

Either that or I just haven't replicated the combination; there may be several. Yuneec's attitude is unacceptable. They should have thanked you and said they'd look into it post haste, then go public if they could replicate the error. This is not just a firmware glitch, but a safety issue as well, not to mention loss of $$$. This is why I like open source so much more than closed systems. Nothing can be hidden or blown off.

 

[PatR]

This is not good and I agree with Glider, this should be openly acknowledged and corrected immediately. Failure to acknowledge would imply intent to deceive. You've certainly done your homework Steve. I don't believe discussing this with any of their C.S. techs will take it anywhere as some of them really don't understand the system all that well. It needs to be elevated to a management level.

From a slightly different perspective, the greatest personal injury liability/risk to the public with this would come from the recreational sector where people might operate by flying over people when flying from here to there. Lord help anyone that would experience an event involving another person. The personal injury and product liability attorneys would be on this like flies on stink. Commercial operators doings things the right way won't be flying over people but a sudden shut down of their aircraft will cost them work, client base, their aircraft, along with the potential of property damage claims. Those that carry hull insurance will file claims for loss of aircraft. With the description of how the failures occur and info in the logs I could see insurance companies going after Yuneec to recover their claim losses. Good idea to address this quickly.

 

[Steve Carr]

Once you know what to look for the problem is easy to spot.
The opening screen in Channel Settings should look like this;


If it looks like either of these, you are in big trouble:

 

[Steve Carr]

This is not good and I agree with Glider, this should be openly acknowledged and corrected immediately. Failure to acknowledge would imply intent to deceive. You've certainly done your homework Steve. I don't believe discussing this with any of their C.S. techs will take it anywhere as some of them really don't understand the system all that well. It needs to be elevated to a management level.

From a slightly different perspective, the greatest personal injury liability/risk to the public with this would come from the recreational sector where people might operate by flying over people when flying from here to there. Lord help anyone that would experience an event involving another person. The personal injury and product liability attorneys would be on this like flies on stink. Commercial operators doings things the right way won't be flying over people but a sudden shut down of their aircraft will cost them work, client base, their aircraft, along with the potential of property damage claims. Those that carry hull insurance will file claims for loss of aircraft. With the description of how the failures occur and info in the logs I could see insurance companies going after Yuneec to recover their claim losses. Good idea to address this quickly.

That was precisely why I called Yuneec when I found the problem. I told them up front my intent was to alert them to the problem and not to make a claim. Sadly I was not only completely blown off but met with a condescending attitude and repeated told I pressed B1. Perhaps 25 times during the conversations. I am aware of other experienced pilots who had the same thing happen, but they were unable to provide their logs. I was able to get one other last week. Just reviewing the remote log the cause was immediately obvious. I asked him to take a pic of the Channel Settings and that is the second picture above.

 

[AH-1G]

That was precisely why I called Yuneec when I found the problem. I told them up front my intent was to alert them to the problem and not to make a claim. Sadly I was not only completely blown off but met with a condescending attitude and repeated told I pressed B1. Perhaps 25 times during the conversations. I am aware of other experienced pilots who had the same thing happen, but they were unable to provide their logs. I was able to get one other last week. Just reviewing the remote log the cause was immediately obvious. I asked him to take a pic of the Channel Settings and that is the second picture above.

Excellent job Steve! If Yuneec decides to lift their noses in the air and not take responsibility, I would think all of us on this Forum could send messages to Yuneec or sign a petition in protest. I agree they MUST resolve this issue. Somebody needs to fix their PR people.

 

[BobW55]

will have to check mine out next time.
I had noticed some strange behavior when landing. I often will use some yaw to line up better before touch down, and have notice some very slight increase in decent at the same time. Will pay more attention next flight. Hope to get out this Saturday to maiden my Volantex Ranger.

 

[PatR]

Looks like an unwanted channel mix has been introduced.