With thrust reversers deployed, the maximum N1 to be considered idle thrust is:

With thrust reversers deployed, the maximum N1 to be considered idle thrust is:

• A. 25%
• B. 30%
• C. 35%
• D. 40%

Answer: (B)

With thrust reversers deployed, the engine should remain in a very low spool condition to ensure stable reverse thrust and avoid stressing the reverser system. This means the engine’s N1 should not be treated as idle once the reversers are out of the travel. The upper limit used to define idle in this configuration is about 30% N1. Keeping N1 at or below this value ensures you’re still in the idle regime, providing sufficient margin for safe operation, stable reverse thrust, and predictable engine behavior. If N1 were allowed to climb higher (toward 35–40%), you’d be moving out of idle, which can change how reverse thrust performs and reduce control- and safety margins during reverse operation.

With thrust reversers deployed, the engine should remain in a very low spool condition to ensure stable reverse thrust and avoid stressing the reverser system. This means the engine’s N1 should not be treated as idle once the reversers are out of the travel. The upper limit used to define idle in this configuration is about 30% N1. Keeping N1 at or below this value ensures you’re still in the idle regime, providing sufficient margin for safe operation, stable reverse thrust, and predictable engine behavior. If N1 were allowed to climb higher (toward 35–40%), you’d be moving out of idle, which can change how reverse thrust performs and reduce control- and safety margins during reverse operation.