OEO fuel scheduling from FADEC will occur with the N1 speed difference between the engines exceeds what percentage?

• A. 5%
• B. 10%
• C. 20%
• D. 15%

Answer: (D)

Balancing thrust between engines is essential for safe handling, so FADEC continuously compares the N1 speeds of both engines. When the difference in N1 grows to fifteen percent, FADEC engages One Engine Out fuel scheduling to bring the two engines back toward each other. N1 reflects thrust, so a large disparity can cause undesirable yaw and uneven loading. The scheduling typically reduces fuel to the engine with the higher N1 (or otherwise shifts fuel to lessen the gap) to realign thrust outputs. This fifteen percent threshold is chosen to avoid constant adjustments from small fluctuations, while still acting promptly to a meaningful imbalance, ensuring safer and more controllable operation.