diff --git a/libraries/AP_Motors/AP_MotorsHeli.cpp b/libraries/AP_Motors/AP_MotorsHeli.cpp
index b06e27da49..e913fb01bd 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli.cpp
@@ -493,6 +493,22 @@ bool AP_MotorsHeli::parameter_check(bool display_msg) const
         return false;
     }
 
+    // returns false if _collective_min_deg is not default value which indicates users set parameter
+    if (is_equal((float)_collective_min_deg, (float)AP_MOTORS_HELI_COLLECTIVE_MIN_DEG)) {
+        if (display_msg) {
+            gcs().send_text(MAV_SEVERITY_CRITICAL, "PreArm: Set H_COL_MIN_DEG to actual min blade pitch in deg");
+        }
+        return false;
+    }
+
+    // returns false if _collective_max_deg is not default value which indicates users set parameter
+    if (is_equal((float)_collective_max_deg, (float)AP_MOTORS_HELI_COLLECTIVE_MAX_DEG)) {
+        if (display_msg) {
+            gcs().send_text(MAV_SEVERITY_CRITICAL, "PreArm: Set H_COL_MAX_DEG to actual max blade pitch in deg");
+        }
+        return false;
+    }
+
     // all other cases parameters are OK
     return true;
 }
diff --git a/libraries/AP_Motors/AP_MotorsHeli.h b/libraries/AP_Motors/AP_MotorsHeli.h
index 2e0d609a79..38d00b7691 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.h
+++ b/libraries/AP_Motors/AP_MotorsHeli.h
@@ -22,8 +22,8 @@
 #define AP_MOTORS_HELI_COLLECTIVE_HOVER_TC      10.0f // time constant used to update estimated hover throttle, 0 ~ 1
 #define AP_MOTORS_HELI_COLLECTIVE_HOVER_MIN     0.3f  // minimum possible hover throttle
 #define AP_MOTORS_HELI_COLLECTIVE_HOVER_MAX     0.8f // maximum possible hover throttle
-#define AP_MOTORS_HELI_COLLECTIVE_MIN_DEG      -10.0f // minimum collective blade pitch angle in deg
-#define AP_MOTORS_HELI_COLLECTIVE_MAX_DEG       10.0f // maximum collective blade pitch angle in deg
+#define AP_MOTORS_HELI_COLLECTIVE_MIN_DEG      -90.0f // minimum collective blade pitch angle in deg
+#define AP_MOTORS_HELI_COLLECTIVE_MAX_DEG       90.0f // maximum collective blade pitch angle in deg
 #define AP_MOTORS_HELI_COLLECTIVE_LAND_MIN      -2.0f // minimum landed collective blade pitch angle in deg for modes using althold
 
 
@@ -267,8 +267,8 @@ protected:
     AP_Float        _collective_min_deg;        // Minimum collective blade pitch angle in deg that corresponds to the PWM set for minimum collective pitch (H_COL_MIN)
 
     // internal variables
-    float           _collective_zero_pct = 0.0f;      // collective mid parameter value converted to 0 ~ 1 range
-    float           _collective_land_min_pct = 0.0f;      // collective mid parameter value converted to 0 ~ 1 range
+    float           _collective_zero_pct;      // collective mid parameter value converted to 0 ~ 1 range
+    float           _collective_land_min_pct;      // collective mid parameter value converted to 0 ~ 1 range
     uint8_t         _servo_test_cycle_counter = 0;   // number of test cycles left to run after bootup
 
     motor_frame_type _frame_type;
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp b/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
index 60ca95f9fe..c3ec056455 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
@@ -377,14 +377,20 @@ void AP_MotorsHeli_Dual::calculate_scalars()
 
     _collective_zero_thrst_deg = constrain_float(_collective_zero_thrst_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective zero thrust point as a number from 0 to 1
-    _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
-    _collective2_zero_pct = _collective_zero_pct;
-
     _collective_land_min_deg = constrain_float(_collective_land_min_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective land min point as a number from 0 to 1
-    _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    if (!is_equal((float)_collective_max_deg, (float)_collective_min_deg)) {
+        // calculate collective zero thrust point as a number from 0 to 1
+        _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+
+        // calculate collective land min point as a number from 0 to 1
+        _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    } else {
+        _collective_zero_pct = 0.0f;
+        _collective_land_min_pct = 0.0f;
+    }
+
+    _collective2_zero_pct = _collective_zero_pct;
 
     // configure swashplate 1 and update scalars
     _swashplate1.configure();
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp b/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
index 00a35f91c3..55da1c237c 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
@@ -149,13 +149,18 @@ void AP_MotorsHeli_Quad::calculate_scalars()
 
     _collective_zero_thrst_deg = constrain_float(_collective_zero_thrst_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective zero thrust point as a number from 0 to 1
-    _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
-
     _collective_land_min_deg = constrain_float(_collective_land_min_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective land min point as a number from 0 to 1
-    _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    if (!is_equal((float)_collective_max_deg, (float)_collective_min_deg)) {
+        // calculate collective zero thrust point as a number from 0 to 1
+        _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+
+        // calculate collective land min point as a number from 0 to 1
+        _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    } else {
+        _collective_zero_pct = 0.0f;
+        _collective_land_min_pct = 0.0f;
+    }
 
     // calculate factors based on swash type and servo position
     calculate_roll_pitch_collective_factors();
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Single.cpp b/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
index fc1d7e8bb5..c8f0aa4edd 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
@@ -324,15 +324,21 @@ void AP_MotorsHeli_Single::calculate_scalars()
         _collective_min = AP_MOTORS_HELI_COLLECTIVE_MIN;
         _collective_max = AP_MOTORS_HELI_COLLECTIVE_MAX;
     }
-    _collective_zero_thrst_deg = constrain_float(_collective_zero_thrst_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective zero thrust point as a number from 0 to 1
-    _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    _collective_zero_thrst_deg = constrain_float(_collective_zero_thrst_deg, _collective_min_deg, _collective_max_deg);
 
     _collective_land_min_deg = constrain_float(_collective_land_min_deg, _collective_min_deg, _collective_max_deg);
 
-    // calculate collective land min point as a number from 0 to 1
-    _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    if (!is_equal((float)_collective_max_deg, (float)_collective_min_deg)) {
+        // calculate collective zero thrust point as a number from 0 to 1
+        _collective_zero_pct = (_collective_zero_thrst_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+
+        // calculate collective land min point as a number from 0 to 1
+        _collective_land_min_pct = (_collective_land_min_deg-_collective_min_deg)/(_collective_max_deg-_collective_min_deg);
+    } else {
+        _collective_zero_pct = 0.0f;
+        _collective_land_min_pct = 0.0f;
+    }
 
     // configure swashplate and update scalars
     _swashplate.configure();