What is the Ground Start N2 range?

• A. 0-40%
• B. 0-45%
• C. 0-50%
• D. 0-55%

Answer: (B)

During a ground start, the starter spins the high‑pressure compressor (N2) from zero up to the point where ignition occurs. The allowed N2 range for this phase is 0 to 45 percent. This window protects the starter and engine components from overspeed and potential damage while you wait for light-off. If you attempt to carry the N2 speed higher than about 45% without ignition, the risk of compressor surge or starter overloading increases, so the start procedure is designed to abort or transition to ignition within that range. Once ignition occurs, N2 will continue rising as the engine spools to idle.