When in armed mode, INTERIM POWER automatically reengages when airspeed is below what speed and nacelle angle is above what degree?

In armed mode, INTERIM POWER automatically reengages when the airspeed drops below 55 knots calibrated airspeed (KCAS) and the nacelle angle is above 70 degrees. This feature is crucial as it ensures that the aircraft maintains optimal performance during low-speed operations and when the rotor blade pitch is set for high power demands, typical of hovering and take-off conditions.

By specifying 55 KCAS and 70 degrees, the system is designed to provide enhanced power and lift when the aircraft is at risk of losing altitude due to insufficient airspeed or excessive nacelle angle, which requires more power to sustain operations. This automatic engagement acts as a safety measure to prevent potential stall or loss of control during critical phases of flight, particularly when transitioning from forward flight to hover or vice versa.

Each of the other options presents speeds and nacelle angles that do not align with the designed operational parameters for automatic reengagement, thereby highlighting the importance of the correct thresholds for ensuring safety and performance.