If the primary induction air opening is blocked, which device allows induction air to continue to the engine?

• A. Alternate air
• B. Altimeter
• C. Alternator/generator
• D. Alternate static source

Answer: (A)

If the primary induction air opening is blocked, the engine still needs air to continue running, so a secondary path is provided through the Alternate Air system. This device opens a separate intake route that feeds air into the induction system when the normal intake is obstructed, allowing the engine to keep drawing air and avoid flameout or rough running. The air from this source may come from a different location (often outside the cowling) and can be warmer or slightly less filtered, so you may notice changes in engine performance and need to monitor the mixture accordingly. The other items listed do not serve to supply induction air: one is a pressure source for the cockpit instruments related to altitude, another generates electrical power, and the last provides a secondary static pressure source for instruments, not air for the engine.