During an engine start with tailwind, which indication must be monitored and verified before starter cutoff?

During an engine start with tailwind, which indication must be monitored and verified before starter cutoff?

• A. N1 increase
• B. N2 increase
• C. EGT rise
• D. RPM drop

Answer: (A)

During a start, the primary signal that the engine is coming to life is the rise of the N1, the speed of the low‑pressure (fan) spool. As the starter drives the engine, N1 should increase steadily toward the target value, showing that air is being drawn through the compressor and that the engine is transitioning toward light-off. Once N1 reaches the designated point and the system expects to sustain operation, the starter is cut off. In tailwind starts, this cue remains the most reliable indicator because it reflects actual spool acceleration and airflow, whereas other signs are either secondary or occur after ignition. An EGT rise can happen once ignition starts, but it isn’t the sole signal to stop the starter, and a simple RPM drop or N2 rise without a corresponding N1 increase doesn’t guarantee a successful start.

During a start, the primary signal that the engine is coming to life is the rise of the N1, the speed of the low‑pressure (fan) spool. As the starter drives the engine, N1 should increase steadily toward the target value, showing that air is being drawn through the compressor and that the engine is transitioning toward light-off. Once N1 reaches the designated point and the system expects to sustain operation, the starter is cut off. In tailwind starts, this cue remains the most reliable indicator because it reflects actual spool acceleration and airflow, whereas other signs are either secondary or occur after ignition. An EGT rise can happen once ignition starts, but it isn’t the sole signal to stop the starter, and a simple RPM drop or N2 rise without a corresponding N1 increase doesn’t guarantee a successful start.