I'm trying to help a friend diagnos the cause of his crash. Below is his description of what happened. What interests me most is the log entry "active control loop failure ". What does that mean and what could caution?

Thanks


What caused my crash? My guess is flybarless but Im Interested in your thoughts.

Maidened my 690sx today that had the following stuff:

Helijive 120
Pyro 700-45
Jr 8717 servos
Bls251 tail servo
Spirit FBL
Futaba 6203sb rx
Optiguard backup

From the start the heli didn't feel very locked in (compared to the 480, Diabolo and oxy I miadened on Spirit in the last month). Forward flight was fine but cyclic stops after a roll were not stable. It would sort of fall out of the sky like my old Mcpx BL.

After the second flight it started flying inconsistent. When doing continuous front flips the rotation would momentarily pause - but it wouldn't do it all the time. Should have landed it then

At the end of the flight i tried doing continuous backflips. After the second flip the rotation speed came way way down (like 5% dual rate). I pulled all the way back on elevator and it slowly came around just enough to do a kind of cool looking sliding crash on the runway. Only damage I can see so far is blades mainsahft and pitch servo horn. All servos are totally functional.

On startup there was no indication that there was bad things in the logs (swash), but I looked anyway and every minute or so it said "active control loop failure".


Any ideas?

Hello Jim,

it is sad that helicopter crashed. If there is even the smallest strange thing, I always recommend to land as soon as possible and carefully examine the helicopter.

I believe that the problem was caused by slipped belt from a pulley, which is quite common issue with Logos. Very often it can't be noticed even during flight. If not slipped, then boom can move during flight. Unfortunately belt can cause a lot of static discharges in both cases and all the electronics will react very strangely and can be even damaged.

Main Loop Hang occured event is mostly caused by such issues (with static discharges or excess noise in the power supply) as described in the manual. This event should never occur if everything is OK.

Can you tell me how belt looked like after the crash?

_________________
Spirit System developer