At what airspeed in airplane mode does the upper conversion protection boundary prevent nacelles from moving off the downstops?

The upper conversion protection boundary is an important feature in aircraft systems that helps maintain nacelle position and function, particularly in transition phases between flight modes. In airplane mode, specifically, the nacelles are prevented from moving off their downstops to ensure that the aircraft remains stable and safe during flight.

In this context, the correct airspeed at which this protection boundary is active is critical for ensuring the aircraft can operate safely without the nacelles inadvertently transitioning to a position that could compromise flight security. The nacelles must remain secured during specific speed ranges to prevent any controlled flight issues.

The speed of 200 KCAS is identified as the correct threshold for the upper conversion protection boundary. At this speed, the aircraft's systems effectively monitor and control nacelle movement, ensuring that they do not move off their designated stops in airplane mode. This is vital for maintaining aerodynamic integrity and operational control of the aircraft.

Understanding this airspeed is essential for pilots and crew to ensure they adhere to operational limits, especially when transitioning from vertical to horizontal flight mode. The choice of 200 KCAS reflects a calculated balance between operational performance and safety, emphasizing the engineering and safety measures in place for aircraft operation.