What is the ITT limit for an assisted air start?

What is the ITT limit for an assisted air start?

• A. 815C
• B. 750C
• C. 900C
• D. 920C

Answer: (A)

During an assisted air start, the engine is brought to light-off with external air, but turbine temperatures still rise rapidly as fuel is introduced. The ITT limit is set at 815°C to protect the turbine blades from thermal stress while allowing a reliable start. This value is chosen specifically for the start mode, balancing safe operation with a successful light-off. Higher limits would risk overheating the turbine during start, while a lower limit would unnecessarily hamper the start sequence and could trip the start protection. Therefore, 815°C is the correct ITT limit for an assisted air start.

During an assisted air start, the engine is brought to light-off with external air, but turbine temperatures still rise rapidly as fuel is introduced. The ITT limit is set at 815°C to protect the turbine blades from thermal stress while allowing a reliable start. This value is chosen specifically for the start mode, balancing safe operation with a successful light-off. Higher limits would risk overheating the turbine during start, while a lower limit would unnecessarily hamper the start sequence and could trip the start protection. Therefore, 815°C is the correct ITT limit for an assisted air start.