After loading 3.6.0 - rc6 got these error messages on PixRacer:
PreArm: RC16 minimum is greater than trim
PreArm: RC15 minimum is greater than trim
PreArm: RC14 minimum is greater than trim
PreArm: RC13 minimum is greater than trim
Did not play with these before but had to set the minimum values lower than the trim values before copter would arm. Don’t have anything on these channels.
Trim values was set 874 and minimum was set to 1100.
Mike
did you solve it please help me with this im having pre arm with problem rc 16 is greater than trim
To fix this you need to go into parameters and change RCTRIM to be the same or greater than RCMIN. I think the default value is 987 and RCMIN is 1000.
Mike
thank you so much, everything now works fine. we are going to fly tomorrow…
Thank you very much! 
Hello -I just came across this thread while trying to troubleshoot. I am getting this error as well. I’m running version v3.6.8. I am a little confused about how to change the parameters. I’m using Mission Planner and looking under Config/tuning, Standard Params, but I can’t find “RCTRIM” or “RCMIN”. I’m guessing I’m looking in the wrong place?
Please disregard; I hopped over to QGroundControl and was able to change the parameters there…
Can’t find “RC_MIN” or "RC_TRIM"m in Mission planner (4.0.3).
But duh…figured out the actual term is RCX_MIN…as in RC16_MIN.
The other thing is the reason this happens in the first place…when doing a radio calibration, and if, say, your FrSky receiver is bound using the 16 channels option, but you calibrate with just 8, there is something about arducopter that kinda randomizes the values for channels 9-16…which sometimes makes the values “wrong” as Mission Planner / Preflight sees them.
Hello mate,
I also encountered this error for Copter-4.0.7, in my case trim was set to 0, so I set it to 1500 for RC16, 15, 14, and 13. and the error disappeared. My question is: is this value correct or I should set another value?
I appreciate your help
@iseries
More than likely, you are not using those channels, so the value is not important. 1500 would be for a stick in the middle, 1000 for like the throttle all the way down.