diff --git a/libraries/AP_Motors/AP_MotorsHeli.cpp b/libraries/AP_Motors/AP_MotorsHeli.cpp
index 3bb6bf95cd..bc9d5c05ae 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli.cpp
@@ -17,6 +17,7 @@
 #include <AP_HAL/AP_HAL.h>
 #include "AP_MotorsHeli.h"
 #include <GCS_MAVLink/GCS.h>
+#include <AP_Logger/AP_Logger.h>
 
 extern const AP_HAL::HAL& hal;
 
@@ -598,3 +599,16 @@ AP_MotorsHeli_RSC::RotorControlState AP_MotorsHeli::get_rotor_control_state() co
     // Should be unreachable, but needed to keep the compiler happy
     return AP_MotorsHeli_RSC::RotorControlState::STOP;
 }
+
+// Update _heliflags.rotor_runup_complete value writing log event on state change
+void AP_MotorsHeli::set_rotor_runup_complete(bool new_value)
+{
+#if HAL_LOGGING_ENABLED
+    if (!_heliflags.rotor_runup_complete && new_value) {
+        LOGGER_WRITE_EVENT(LogEvent::ROTOR_RUNUP_COMPLETE);
+    } else if (_heliflags.rotor_runup_complete && !new_value && !_heliflags.in_autorotation) {
+        LOGGER_WRITE_EVENT(LogEvent::ROTOR_SPEED_BELOW_CRITICAL);
+    }
+#endif
+    _heliflags.rotor_runup_complete = new_value;
+}
diff --git a/libraries/AP_Motors/AP_MotorsHeli.h b/libraries/AP_Motors/AP_MotorsHeli.h
index c3c5cfc0c1..172fd39c61 100644
--- a/libraries/AP_Motors/AP_MotorsHeli.h
+++ b/libraries/AP_Motors/AP_MotorsHeli.h
@@ -233,6 +233,9 @@ protected:
     // update turbine start flag
     void update_turbine_start();
 
+    // Update _heliflags.rotor_runup_complete value writing log event on state change
+    void set_rotor_runup_complete(bool new_value);
+
     // enum values for HOVER_LEARN parameter
     enum HoverLearn {
         HOVER_LEARN_DISABLED = 0,
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp b/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
index 2849b3c85c..c9b645056d 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Dual.cpp
@@ -374,7 +374,8 @@ void AP_MotorsHeli_Dual::update_motor_control(AP_MotorsHeli_RSC::RotorControlSta
     }
 
     // Check if rotors are run-up
-    _heliflags.rotor_runup_complete = _main_rotor.is_runup_complete();
+    set_rotor_runup_complete(_main_rotor.is_runup_complete());
+
     // Check if rotors are spooled down
     _heliflags.rotor_spooldown_complete = _main_rotor.is_spooldown_complete();
 }
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp b/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
index af66de81db..817e89f1ac 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Quad.cpp
@@ -159,7 +159,8 @@ void AP_MotorsHeli_Quad::update_motor_control(AP_MotorsHeli_RSC::RotorControlSta
     }
 
     // Check if rotors are run-up
-    _heliflags.rotor_runup_complete = _main_rotor.is_runup_complete();
+    set_rotor_runup_complete(_main_rotor.is_runup_complete());
+
     // Check if rotors are spooled down
     _heliflags.rotor_spooldown_complete = _main_rotor.is_spooldown_complete();
 }
diff --git a/libraries/AP_Motors/AP_MotorsHeli_Single.cpp b/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
index 65213c60bf..a996fb7d04 100644
--- a/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
+++ b/libraries/AP_Motors/AP_MotorsHeli_Single.cpp
@@ -362,7 +362,7 @@ void AP_MotorsHeli_Single::update_motor_control(AP_MotorsHeli_RSC::RotorControlS
     }
 
     // Check if both rotors are run-up, tail rotor controller always returns true if not enabled
-    _heliflags.rotor_runup_complete = ( _main_rotor.is_runup_complete() && _tail_rotor.is_runup_complete() );
+    set_rotor_runup_complete(_main_rotor.is_runup_complete() && _tail_rotor.is_runup_complete());
 
     // Check if both rotors are spooled down, tail rotor controller always returns true if not enabled
     _heliflags.rotor_spooldown_complete = ( _main_rotor.is_spooldown_complete() );