In TOGA mode, which pair correctly lists the N1 and N2 maximum values?

In TOGA mode, which pair correctly lists the N1 and N2 maximum values?

• A. N1 99.5%, N2 99.4%
• B. N1 99.0%, N2 99.4%
• C. N1 99.5%, N2 98%
• D. N1 100%, N2 99.4%

Answer: (A)

In TOGA mode the engine control aims for maximum thrust while staying within safe limits. The N1 and N2 values shown represent the highest speeds the engines are allowed to reach under TOGA, as protected by the engine limiters. For this configuration, the maximum N1 is 99.5% and the maximum N2 is 99.4%. Those slight shortfalls from 100% provide the necessary margin to prevent compressor surge or turbine overspeed during rapid throttle movement. This pairing is the best because it reflects the actual limits the FADEC enforces for TOGA thrust. The other options either lower one of the spool speeds, or push N1 to 100%—which isn’t permitted by the protection system and would risk overspeed.

In TOGA mode the engine control aims for maximum thrust while staying within safe limits. The N1 and N2 values shown represent the highest speeds the engines are allowed to reach under TOGA, as protected by the engine limiters. For this configuration, the maximum N1 is 99.5% and the maximum N2 is 99.4%. Those slight shortfalls from 100% provide the necessary margin to prevent compressor surge or turbine overspeed during rapid throttle movement.

This pairing is the best because it reflects the actual limits the FADEC enforces for TOGA thrust. The other options either lower one of the spool speeds, or push N1 to 100%—which isn’t permitted by the protection system and would risk overspeed.