Quad had mind of its own


New member
I am running kiss fc, kiss 24 amp esc, frsky x4r receiver and max 2204 red bottom motors. I started to fly my quad line of sight today, flew for about 1 min doing a few flips and things. I came into land and it stopped receiving inputs from my controller. When it was about a foot up from the ground it flipped over and went straight into the ground (could have been full speed, but it was hard to tell). I tried to disarm it right away but it wouldn’t disarm. I just waited, hoping that I could just wait for the battery to die. I waited about 30 seconds and then the motors all of sudden stopped. When i carefully walked up to my quad, two of my props were completely gone and two were half shredded, all of the nut caps were still on the motors. Now it wont even arm when I try to turn it on. I have no idea what is going on, thanks for the help.


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Are you sure the receiver is still sending a signal to the FC? If it’s not responding to the radio, it sounds like a failsafe issue.

Liam B

Well-known member
Definitely a radio problem. That’s really uncharacteristic of the KISS FC. In what condition are your receiver antennas and how is old is the radio? What kind is it?


New member
I have a Taranis X9D Plus, my antennas are fine. I recently pulled my frame apart and cleaned off the electronics and made sure the connections and sounder joints were still looking okay. So as a couple of days ago my antennas looke fine. I have flown a couple of batteries since the rebuild.

To check if the receiver is still sending signal to the kiss fc should i open the kiss GUI?


Crashing Ace
check the radio first because that's normally the root of the problem but id also make sure the receiver is okay and that it didn't go into some sort of weird failsafe.Last thing you may want to check is the failsafe protocol on the fc it should not be the problem but always good to check.


Wake up! Time to fly!
From the sounds if it. You went into fail safe just as you landed. The reaction of the quad going bonkers sounds like your fail safe protocol is set for hold last known inputs. This would have kept things as your last input which is why it would not stop the motors and the FC has no idea it was a fail safe so more then likely air mode was what made it go bonkers.

The X4r is a good receiver and fail safes are few and far between but can happen. How are your antennas mounted? A picture would be nice so we can see if there are any lines of radiation that are interfered with like the chance the FPV antenna got between you and the receiver and over powered or blocked radio signals.

As for the radio set up you want to go into the models configuration page and set the fail safe to no signal so the fail safe will shut everything off. Then in the KISS gui you want to set the FS Levelmode under the quad picture to 0.

Check the antennas really good specially where the clear jacket and wire that is exposed on the ends is not broken right at the area the outer sleeve was removed. This is really common and hard to see but that area gets flexed a lot if you do not shrink tube your antennas to protect them.


How would I check the radio for problems? How do I know if it went into failsafe?

Remove props.

Plug FC into PC and open KISS GUI, connect to your FC.

Turn on radio.

No propellers installed...right?

Plug in battery (I'm not sure if FRSKY receivers will accept power from the FC over USB...sometimes its hit or miss so we're plugging in the battery to make sure).

Open up the 'Data Output' tab in the KISS GUI and give the sticks on the radio a wiggle. You should see the values under 'receiver' changing. If they are moving, try taking a few steps away from your quad with your radio and repeat. We're looking to see if your connection drops out.

If they're not changing either your receiver is not talking to your flight controller, or your transmitter is not talking to your receiver. Easiest thing to check here is that the lights on your receiver are green and solid (I think that's how FRSKY indicates good communications between TX and RX) and the wiring between the FC and receiver is good. Might even consider re-wiring the receiver to make 100% sure there aren't any internal breaks in the wires.

Do you have any other models bound to your Taranis? You can try it out with them and if it works you can eliminate the transmitter from the equation.