The FADEC normally provides thrust limit modes with reference to which parameter?

The FADEC normally provides thrust limit modes with reference to which parameter?

• A. N1
• B. N2
• C. EGT
• D. Torque

Answer: (A)

Thrust limit modes are referenced to N1 because N1 is the speed most directly tied to the engine’s thrust and is the parameter the FADEC uses to regulate fuel and power output. The FADEC sets limit values as target N1 levels for different modes (takeoff/go-around, climb, maximum continuous) and trims fuel to keep N1 from exceeding those limits under varying conditions. N2 relates to core speed but isn’t the basis for thrust limiting; EGT is monitored to protect against overheating, not to define thrust limits; and torque is a byproduct of engine operation, not the reference used for limiter scheduling. So N1 is the appropriate reference for thrust limit modes.

Thrust limit modes are referenced to N1 because N1 is the speed most directly tied to the engine’s thrust and is the parameter the FADEC uses to regulate fuel and power output. The FADEC sets limit values as target N1 levels for different modes (takeoff/go-around, climb, maximum continuous) and trims fuel to keep N1 from exceeding those limits under varying conditions. N2 relates to core speed but isn’t the basis for thrust limiting; EGT is monitored to protect against overheating, not to define thrust limits; and torque is a byproduct of engine operation, not the reference used for limiter scheduling. So N1 is the appropriate reference for thrust limit modes.