Engine shut down mid air!

[wings]

Thank you.

 

[Steve Carr]

From what I can see B1(red button - motor start/stop) was activated at 14:36:45 for about 3 seconds which initiated the descent. I can only assume this was accidental or a mechanical/electrical fault, as the owner has been flying for more than a year.
About a second later the intentional press of B1 occurs trying to restart the motors that lasts for about 8.5 seconds.

Later this afternoon I took another look and compared the files again. I overlooked comparing the final descent to the throttle channel. It is obvious the H started the descent on it's own with no stick command to do so. This is very definitely a fault in the H, most likely the flight controller.

Bottom line here......there is no pilot error and there is nothing the pilot could have done to save the flight.

 

[DoomMeister]

Later this afternoon I took another look and compared the files again. I overlooked comparing the final descent to the throttle channel. It is obvious the H started the descent on it's own with no stick command to do so. This is very definitely a fault in the H, most likely the flight controller.

Bottom line here......there is no pilot error and there is nothing the pilot could have done to save the flight.

Did the descent start before the first drop to zero on the throttle channel? I was suspecting a fault in the start/stop switch on the ST-16, but you are definitely way more qualified than myself in these manners. I do agree that there was most likely an equipment failure of some sort.

It has to be gut wrenching to see your craft making an uncontrolled descent or flying off on its own. I feel for @Arclat

 

[Steve Carr]

Did the descent start before the first drop to zero on the throttle channel?

Yes. The descent started a full 3 seconds before the motors completely shut down while the stick was centered.

Oddly, I just reviewed a similar crash a few days ago. The motors did not shut down, they went to idle and, again with the throttle at center stick.

 

[wings]

Considering how many of these (H) have been made how rare is this type of event? Or is it happening more often now?

 

[h-elsner]

Sorry to say, but for me it looks like the red button was pressed for a long time (too long). It is normal, that the copter starts to descent once the button was pressed because Throttle and B1 is mixed. B1 means go down to the copter, via SW additionally this will detected as motor cut if longer than 3s. Some guys land the copter by tipping frequently on the red button (shorter than 3s of course). This is no bug but a "feature".

I don't believe that channel settings have influence here. No other channel has changed at the time the signal comes from B1.

Overview:

Cutted to see the time line better:

br He

 

[wings]

So what do you think caused the bird to fall from the sky?

 

[h-elsner]

B1 was pressed longer that 3s. Looks like a pilot error from FlightLog p.o.v.
2-3m/s is the normal descent rate, after 3s it goes faster.

br HE

 

[Steve Carr]

B1 was pressed longer that 3s. Looks like a pilot error from FlightLog p.o.v.
2-3m/s is the normal descent rate, after 3s it goes faster.
br HE

That was my initial determination, but when I went back and looked more closely, the H started it's descent well before the mode changed from 3 to 16 while the throttle was untouched. The OP indicates he tried to restart the motors as it fell which is verified by both files.
"During the free fall I pushed the start/stop button to recover...but :-(."

 

[h-elsner]

It starts to descent shortly after the B1 button was pressed and this is normal. You can control the H with the B1 button (due to mixed channels) to bring it down. But never press the button too long.
If you press longer than 3s then ... **** happens. See post #26.

br HE

 

[wings]

We all knew about using the red button when 1 or 2 ft above the ground to achieve a better landing. I think Steve Carr still has a sticky note about that. When did pilots start using the red button for decent from altitude, if that is what happened. Why would anyone do that, with its inherent dangers, instead of using the left stick??

 

[Steve Carr]

The OP indicates he has a protective cover over Big Red. I have to believe he only pushed the button in an attempt to restart the motors. I know of no one who uses the button at altitude to intentionally reduce altitude.

 

[wings]

Especially if he has a cover over big red!

 

[Arclat]

Many thanks, everybody!
The H hovered about 17 meters above t/o point. Line of sight. B1 was covered by the safety cover. I saw the H falling. Actually behind a building near to beach. To open the cover and push B1 to recover/to restart the engine needed less 1/10 of a second. And...naturally I kept pressing. The H was already out of line of sight behind the building. I don't tent to panic. But useless...the H crashed. I believe that B1 is faulty. Mechanical or electrical. Yuneec Europe will find out.
PatR wrote: "Perhaps the dreaded red button malady?"
I am not sure if I understand that correct/well. Any problems with B1? Which pilot presses B1 for 3 seconds in flight by accident? And - why?...is it even possible to cut the engines in flight? I flew the Ascending Technologies Falcon 8 hundreds of hours. Professional. No chance at all to cut the engines in flight and on ground 2 hands and 4 fingers are needed to excute engine shut down. Quite an interesting discussion!
Again: many thanks to you all! I'll come back to this...for sure with final results!
Arclat

 

[biltno]

I’m by far not as educated as most of the guys here ... Steve, PatR, DoomMiester, h-Elsner....just to name a few but it sounds to me like OP is positive the power button wasn’t pressed until a last attempt to recover. I know if I was flying I would certainly know if I made the dreaded error. It’s these problems that we hope can be solved to further educate ourselves. Is it possible an electrical failure can make telemetry show otherwise? It certainly looks that way to me.