A red N2 RPM indication alerts the pilot to?

A red N2 RPM indication alerts the pilot to?

• A. Normal Operation
• B. A Minor Fault
• C. An Operating Limit Being Exceeded
• D. A Fuel Balance Issue

Answer: (C)

Red N2 RPM means the APU’s core speed has exceeded its safe operating limit. N2 is the speed of the high‑pressure spool, and when the indicator turns red it signals a protective condition: the parameter is outside approved bounds and could cause damage if not corrected. This is a serious warning that requires following the abnormal procedures to bring the speed back into limits or shut the APU down as directed. This isn’t normal operation, and it isn’t a minor fault. It’s not indicating a fuel balance issue, which would show a different warning related to the fuel system. Amber warnings would suggest caution, but red means an operating limit has been exceeded and action is required immediately.

Red N2 RPM means the APU’s core speed has exceeded its safe operating limit. N2 is the speed of the high‑pressure spool, and when the indicator turns red it signals a protective condition: the parameter is outside approved bounds and could cause damage if not corrected. This is a serious warning that requires following the abnormal procedures to bring the speed back into limits or shut the APU down as directed.

This isn’t normal operation, and it isn’t a minor fault. It’s not indicating a fuel balance issue, which would show a different warning related to the fuel system. Amber warnings would suggest caution, but red means an operating limit has been exceeded and action is required immediately.