Maybe you can help me find reasons.

The heli is 700 Kraken, Spirit Pro, ESC Kosmik 200, FrSky Horus X10 + XR4SB receiver, running openTX.

What happened is, I lost control over the heli in the middle of the flight. Could not control any channel. A moment later the motor went off, which I think was a failsafe engaged. Then half second later everything went back to normal, motor went through quick spoolup (luckily failsafe was set for autorotation bailout), which let me take control and land safely.

When this happened, radio was telling "telemetry lost". Nothing about link problems, like RSSI low, as far as I know.

My power setup is:
- Kosmik BEC connected to Spirit with both wires, set to 7.8V
- 2S 450 mAh Lipo connected to the receiver, had 7.8V before flight
- receiver and FBL connected as usual over SBUS

Unfortunately I have no logs from OpenTX.
I have the log from Kosmik, but it's just normal - it received THR level to turn off the motor, and half second later to turn it back on. BEC voltage is stable in this log.

Spirit does not show me any log from previous flight. I couldn't check in the field. I thought it would show me something when I come back home, but it doesn't show any previous flight log available.

When I came back home and connected the heli to PC, it turned out my PC software is 2.7 and Spirit unit has 2.6.2. So I closed the software (without trying to do anything else), installed 2.6.2 and started again. And then tried to see the log. But it doesn't show me any message about "previous flight log" available. Could this procedure delete the previous flight log?

Is any chance to get to this log? Could it be still in memory?
Or does it mean there were no problems and nothing was logged?

I'm puzzled.. I think power problem is very unlikely. I think maybe Rx-FBL wire could have issues, but I think then FBL would log "receiver signal lost". What could it be?

Hm, ok, I just realized that it must be something between Rx and Tx. Otherwise I wouldn't get "telemetry lost" warnings. Even if Spirit would restart or anything, there could be some telemetry data missing, but general telemetry would be there. So probably from Spirit point of view there was nothing weird. The Rx started the failsafe.

Hello,

are you able to distinguish between Throttle signal lost or Throttle signal is low - to turn off the motor normally.

If signal was not lost, then it was failsafe.
But if failsafe engaged then it must be logged in the Spirit unit.

If Throttle signal was lost, then the reason for lost control occured rather in the unit.
This lost could be due to strong static discharge or very big voltage drop. But also voltage drop would be logged.

So static discharge is the most likely.

Please check "boom" grounding from tail to motor.

_________________
Spirit System developer

Thr wasn't lost. It went to a level which is low enough to stop the motor, but above 0, thanks to which spool up was fast (AR bailout).

But I think the bailout was from the receiver, not FBL. I have failsafe setup in both, because having FS only in FBL somehow didn't work for me. So I think FBL didn't even know anything was going wrong.

I'll check antennas and stuff...

What FrSky firmware version are you using in the Rx and Tx? There is a bug in Accst d16 version 1 and Access. There is a new Accst Version 2.1 which fixes the bug. They are still working on an update for Access. https://www.rcgroups.com/forums/showthr ... o-affected

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Thanks Denis, I was checking this out already. It looks like my situation is little different, because the is supposed to keep channels locked in last position, which wouldn't result in a failsafe. But maybe it is related.. I do use ACCST v1. I will be updating all my gear soon, but I wonder how to make sure the problem is gone. Scratching my head here..

I believe the bug in accst is fake to get you to update to access or accst 2. Both are now encrypted protocols so 3rd party receivers can't be used any more with frsky radios. Frsky are trying to lock customers in to their receivers and block 3rd party gear.

I think the update of Accst D16 v2 i.e. the Accst V2.1 isn't "encrypted" anymore. The so called encryption in the Accst D16 v2 was just data whitening to improve bit errors rejection according to that thread on Rc groups. I can't talk for Access though as that's encrypted.

Also the guys over there (Rcgroups) have extensively tested Accst D16 v1 and the bug really exists where the servos go hardover and lock.

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