The Acro levelling rate is larger than the angle gain

Stops itAutoTune and controlCopter only

What ArduPilot says:

PreArm: Check ACRO_BAL_ROLL/PITCH

ACRO_BAL_ROLL and ACRO_BAL_PITCH set how fast the copter returns to level in Acro and Sport when the sticks are released (1 by default). Each must not be larger than the angle controller's P gain for the same axis: ATC_ANG_RLL_P and ATC_ANG_PIT_P (4.5 by default). The message appears whether or not you fly Acro.

What to do, most likely first

ATC_ANG_RLL_P or ATC_ANG_PIT_P was lowered below 1, by hand or by a parameter file for a very large copter.
CheckCompare the two pairs of numbers.
FixLower ACRO_BAL_ROLL and ACRO_BAL_PITCH to the angle gains or below, or bring the angle gains back into their normal range of 3 to 12.
ACRO_BAL_ROLL or ACRO_BAL_PITCH was raised above its range of 0 to 3.
FixSet both back to 1.

4.7 also refuses a negative ACRO_BAL_ROLL or ACRO_BAL_PITCH.

Parameters to look at

Parameter	What it is
`ACRO_BAL_ROLL`	Acro Balance Roll
`ACRO_BAL_PITCH`	Acro Balance Pitch
`ATC_ANG_RLL_P`	Roll axis angle controller P gain
`ATC_ANG_PIT_P`	Pitch axis angle controller P gain

The code that sends it

PreArm: Check ACRO_BAL_ROLL/PITCH

ArduCopter/AP_Arming.cpp AP_Arming_Copter::parameter_checks() · Open in ArduPilot Copter-4.6.3

ArduCopter/AP_Arming_Copter.cpp AP_Arming_Copter::parameter_checks() · Open in ArduPilot Copter-4.7.1