Thrust rating on an FADEC controlled engine can be changed by.

• A. Varying ballast resistor in the EGT system.
• B. Changing the engine rating plug.
• C. Varying the EPR datum plug.
• D. Adjusting the FADEC software.

Answer: (B)

The thrust limit on a FADEC-controlled engine is set by the engine rating plug. This plug is a hardware limiter that defines the maximum allowable thrust by constraining the FADEC’s fuel scheduling and performance limits. Swapping in a different rating plug changes that maximum, allowing either more or less thrust without altering sensor signals or the software logic. The ballast resistor in the EGT system only affects temperature sensing, not thrust limits; the EPR datum plug calibrates how EPR is interpreted, not how much thrust the engine can produce. While FADEC software governs how the engine responds to commands, the official thrust rating is determined by the installed rating plug, making it the correct mechanism to change thrust rating.