What is the transient N1 limit for take-off operations?

• A. 102%
• B. 103.2% for 5 minutes
• C. 108% for 10 seconds
• D. 103.8% for 30 seconds

Answer: (D)

The transient N1 limit for take-off operations specifies a maximum allowable N1 percentage that can be maintained for a short duration during critical phases of flight, such as take-off. The correct answer highlights that the transient N1 limit is 103.8% for a period of 30 seconds. This limit allows for a slight increase in engine thrust above normal operating parameters, which is particularly useful during take-off when maximum performance is required.

The specification of 30 seconds provides a clear time constraint, ensuring that while the engine can produce this increased power, it must not exceed this limit for an extended period, thus safeguarding against potential engine damage or excessive wear. This duration aligns with take-off scenarios where brief surges in power can be crucial for overcoming initial drag and achieving lift.

In contrast, the other options present differing limits or durations that would not be suitable for standard take-off operations, as they either exceed operational guidelines or imply longer durations that could lead to reliability concerns regarding engine performance and safety.