Your Throttle Failsafe is not enabled.That’s why it didn’t switch to RTL.
PARM, 85595449, FS_THR_ENABLE, 0
PARM, 85595466, FS_THR_VALUE, 975
Set to 1 to enable and check it changes when you switch the radio off in the Failsafe page of Mission Planner,preferably before take off.It can save you a lost copter.
Fence was not enabled either,which is a back up if anything goes wrong with other failsafes.
PARM, 85671940, FENCE_ENABLE, 0
PARM, 85671965, FENCE_TYPE, 7
In fact you had zero failsafes operable.
PARM, 85594902, FS_BATT_ENABLE, 0
PARM, 85594920, FS_BATT_VOLTAGE, 10.5
PARM, 85594938, FS_BATT_MAH, 0
PARM, 85594957, FS_GCS_ENABLE, 0
All of them are there to save your copter from your mistakes.It’s well worth spending a bit of time in the failsafes page of the wiki.It’s saved me a few losses over time,including last weekend with a 960 hexacopter carrying an expensive camera.
http://ardupilot.org/copter/docs/failsafe-landing-page.html
Are you using just the internal Pixhawk compass ? If not,and you’re using one in the GPS puck,you need to enable compass as external,to avoid it losing position.
PARM, 85598393, COMPASS_ORIENT, 0
PARM, 85598424, COMPASS_EXTERNAL, 0 - set to 1 if in the GPS puck.
As noted above you have corrupt parameters in the servo settings relating to motor output, unless you are using a different channel for motor output.This means you must be using channels 1,3,4,5,6 and number 7 is relating to motor 2.Which can be explained by the way it’s wired up.So you’d better explain that one.I’d expect motor 2 to be on channel 2 and not 7 unless it’s been re-mapped.
PARM, 85704878, SERVO2_FUNCTION, 0
PARM, 85708805, SERVO7_FUNCTION, 34