Pixhawk 3pro and Failsafe

I am setting up a single rotor with Pixhawk and Sirius F9P RTK .
I am now in the final stages off bench testing before air time :slight_smile: but i have wonder if someone could verify some thing regarding the Failsafe feature .

-I’m using Arducopter .
-I’m using Futaba Sbus receiver connected to the RC in off Pixhawk 3 .
-I also have a RFD 868/900 telemetry radio .

  • my throttle signal out to the ESC’s are set to PASSTHROUGH cause I am using ESC internal governor and want to adjust that signal easily through rc radio function curve .

Online I read that channel 3 needs to see a certain / low PWM to trigger Failsafe and for the Channel 8 throttle channel witch is in PASSTHROUGH I need the Channel 8 in RC radio to Hold last known signal to make the bird not fall out off the sky due to engine shutdown .
However- I am not able to set a hold value on the Receiver for certain embedded channels in the Sbus signal . I can only determine what the Should happen with the Output pin/rc receiver out channel in a signal loss event .
AKA I can make the whole Sbus output hold all off the values, but then Pixhawk won’t see signal loss on channel 3 and go to Failsafe.

So - I have set the Sbus on my Receiver to shut off and that throughs the Pixhawk into Failsafe . No problem.
But my Channel 8 PASSTHROUGH ( motor rpm) also works as I want it to ( so all is actually just fine ) but I would like some reassurance that it is by design not luck. Cause all other threads online suggests that with current configuration the motor should shut off.
-This has been tested on the bench with Armed and disarmed.

  • it has been tested outside with GPS signal and motor running . Loss off signal makes it go to Failsafe and motor is still running .
  • I have thested it with loss off just rc receiver signal.
    -I have tested it with loss off both RC and Telemetry link.
    -I have tested it by pulling the Sbus cable.
    All the above triggers a Failsafe (RTL) and keeps the motor on.

Could someone verify that this is by design ?.