Which statement is true about redline overspeed protection in alternate modes?

Which statement is true about redline overspeed protection in alternate modes?

• A. It is not available in soft alternate mode
• B. It is weaker in alternate mode
• C. It is the same as in normal mode
• D. It is provided in both normal and alternate modes

Answer: (D)

Redline overspeed protection exists to prevent the APU from spinning beyond the maximum safe speed. It must be active regardless of how the unit is being operated, including alternate modes. Even when the system is in an alternate mode, the protection function remains in place to intervene if RPM approaches the redline, typically by reducing fuel or shutting down the spool to prevent damage. The exact behavior or thresholds in alternate modes may differ from normal mode, but the protection itself is still provided in both. That’s why the statement that it is provided in both normal and alternate modes is the best answer. The other options incorrectly imply the protection isn’t available, is weaker, or is guaranteed to be identical in alternate mode.

Redline overspeed protection exists to prevent the APU from spinning beyond the maximum safe speed. It must be active regardless of how the unit is being operated, including alternate modes. Even when the system is in an alternate mode, the protection function remains in place to intervene if RPM approaches the redline, typically by reducing fuel or shutting down the spool to prevent damage. The exact behavior or thresholds in alternate modes may differ from normal mode, but the protection itself is still provided in both. That’s why the statement that it is provided in both normal and alternate modes is the best answer. The other options incorrectly imply the protection isn’t available, is weaker, or is guaranteed to be identical in alternate mode.