FADEC locks in the final N1 computation at takeoff when the aircraft reaches which speed?

FADEC locks in the final N1 computation at takeoff when the aircraft reaches which speed?

• A. 60 Knots
• B. 62 Knots
• C. 65 Knots
• D. 70 Knots

Answer: (C)

During takeoff, FADEC determines the target N1 from weight, configuration, air temperature, and other data, but it needs reliable engine and air data to lock that value in. The CRJ-550 uses 65 knots indicated airspeed as the point where the final N1 computation is locked. At 65 knots IAS, the engine sensors and air data systems have stabilized enough for the FADEC to fix the N1 target and hold it through rotation and the initial climb. Locking too early could let transient readings skew the thrust setting, while locking later could cause thrust changes during liftoff. So 65 knots IAS is the threshold where the final N1 is locked in.

During takeoff, FADEC determines the target N1 from weight, configuration, air temperature, and other data, but it needs reliable engine and air data to lock that value in. The CRJ-550 uses 65 knots indicated airspeed as the point where the final N1 computation is locked. At 65 knots IAS, the engine sensors and air data systems have stabilized enough for the FADEC to fix the N1 target and hold it through rotation and the initial climb. Locking too early could let transient readings skew the thrust setting, while locking later could cause thrust changes during liftoff. So 65 knots IAS is the threshold where the final N1 is locked in.