autotest: Modified test to capture tailsitter bug

Author: Georacer

Tools/autotest/quadplane.py

@@ -1190,12 +1190,25 @@ def CopterTailsitter(self):
         )
 
         self.reboot_sitl()
+        servo_under_test = 7  # We want to examine servo 7, assuming it's NOT covered by Q_TAILSIT_MOTMX.
+        servo_string = f"SERVO{servo_under_test}_FUNCTION"
+        self.progress('Assert that the servo is a quad motor')
+        assert self.get_parameter(servo_string) >= 33 and self.get_parameter(servo_string) <= 36
+        min_pwm = self.get_parameter("Q_M_PWM_MIN")
+
         self.wait_ready_to_arm()
         self.takeoff(60, mode='GUIDED')
+        self.progress("Starting LOITER")
+        self.change_mode("LOITER")
         self.context_collect("STATUSTEXT")
+        self.delay_sim_time(20)  # Wait for the transition to be done and no longer assisting.
+        servo_pwm = self.get_servo_channel_value(servo_under_test)
+        if servo_pwm != min_pwm:
+            raise NotAchievedException(f"The VTOL motor did not stop: {servo_pwm} != {min_pwm}")
+        self.context_clear_collection("STATUSTEXT")
         self.progress("Starting QLAND")
         self.change_mode("QLAND")
-        self.wait_statustext("Rangefinder engaged", check_context=True)
+        self.wait_statustext("Rangefinder engaged", check_context=True, timeout=60)
         self.wait_disarmed(timeout=100)
 
     def setup_ICEngine_vehicle(self):