The maximum N1 to be considered idle thrust with thrust reversers deployed is:

The maximum N1 to be considered idle thrust with thrust reversers deployed is:

• A. 20%
• B. 30%
• C. 40%
• D. 50%

Answer: (B)

When thrust reversers are deployed, the engine speed that counts as idle is kept very low to ensure reverser operation remains effective and the engine remains stable. The defined limit for idle thrust in this condition is 30% N1. This means that if N1 is at or below 30%, the engine is still considered idling even with the reversers out, which supports safe handling and controllability on the ground. Choosing 30% reflects a boundary where thrust is minimal enough to be considered idle without risking instability or unintended thrust levels. Values at 40% or 50% N1 would indicate a higher thrust state, not idle, even with reversers deployed. A value around 20% would be outside the typical idle range used for this determination and isn’t the standard threshold in procedures.

When thrust reversers are deployed, the engine speed that counts as idle is kept very low to ensure reverser operation remains effective and the engine remains stable. The defined limit for idle thrust in this condition is 30% N1. This means that if N1 is at or below 30%, the engine is still considered idling even with the reversers out, which supports safe handling and controllability on the ground.

Choosing 30% reflects a boundary where thrust is minimal enough to be considered idle without risking instability or unintended thrust levels. Values at 40% or 50% N1 would indicate a higher thrust state, not idle, even with reversers deployed. A value around 20% would be outside the typical idle range used for this determination and isn’t the standard threshold in procedures.