Pixhawk 2.1 with Futuba SG14 - Unpredictable Mystery!

Okay here is what happened!

1. We power up all the devices.
2. Switch ON radio Tx
3. Arm the Safety Switch.
4. Slowly increase the Throttle

All fine now...
Suddenly, the Quad goes full power, blasting all the motors and Mission Planner connected via Telemetry says " No RC Input". No controls work, Disarm sequence not identified.
And Finally Stopped the erratic behavior by pressing the Safety switch on the HERE GPS.

Thank God, for the Motors didn't have any props, Had it been in place, I still what our posistion would have been! This sort of encounter is quite new, as the same configuration worked for us many times in the past.

Now Comes the Investigation part, We took the Quad back, Reflashed the pixhawk 2.1 with firmware and ran the Wizard. Now, the Pixhawk doesn't even recognize the Futuba RC reciever!
However, when we connected an alternate model Avionic Radio System, the pix was able to identify it.

What Could be possibly wrong!?

Quad Details

Tarot 650 Sport Frame
Emax MT4114-340KV - 15" props
Hobbywing 30A ESC
Pixawk 2.1 with Here+ GPS ( Firmware: APM:Copter:Quad: 3.5.3)
Battery Tattu - 6S- 1000mAh

Radio - Futuba 14SG as TX and R7008SB as the Rx.

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  • Do you have log-file?

    I've had bad experience with SBUS receiver on Pixhawk 2.1 /Cube before (first or second batch).   Loss of rc signal from SBUS-receiver to pixhawk, but full signal from receiver to controller (Taranis)..

  • Check that the radio and receiver are working correctly by another means. Ignore the FC and connect servos directly to the receiver (if that's possible) and see if they work OK. If not, test the Tx with a different receiver if you have one. 

    It would seem to me that the issue is somewhere in your Tx-Rx, nothing to do with the Pix. You need to determine which of the two is faulty and replace it.

  • Hi, The order you have mentioned1,2,3,4  if right may cause the problem. Always switch ON the transmitter nd then only power the copter, i.e. Rx to be power after switch on the Tx. This may cause the problem. Any way you can check the log for details.

  • If that is the case, Why is the Pixhawk not recog. it after re installation of firmware? 
    Although the Reciever and Tx are binded, the signals are not captured by Pixhawk! :(

    looninho said:

    Hello Escobar,

    It seems that your Futaba Tx enters the failsafe mode.

    check in failsafe option if throttle faisafe is activated.


  • Hello Escobar,

    It seems that your Futaba Tx enters the failsafe mode.

    check in failsafe option if throttle faisafe is activated.


  • Because you do not have any props on your testing is invalid.

    The only valid "no props" test is the motor test in Mission Planner > Initial Setup > Optional Hardware > Motor Test, and this test is only valid for testing motor order and motor direction, and for setting motor speed at idle.

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