In a single staged supercharger, the position of the throttle butterfly is governed by two things. What are they?

• A. Throttle position and altimeter setting.
• B. Engine RPM and intake air temperature.
• C. Fuel pressure and oil pressure.
• D. Servo mechanism and Aneroid capsule.

Answer: (D)

The throttle butterfly in a single-stage supercharger is controlled by two things: a servo mechanism and an aneroid capsule. The servo mechanism responds to the pilot’s throttle input, positioning the butterfly to regulate how much air enters the supercharger. The aneroid capsule senses ambient pressure (providing altitude information) and adjusts the servo’s signal accordingly, so the system can maintain the desired manifold pressure as altitude changes. This combination lets the engine keep a consistent boost across different flight levels.

Why the other ideas don’t fit: the altimeter setting is just a cockpit instrument reference and isn’t used to control the butterfly. Engine RPM and intake air temperature influence performance but aren’t the direct controlling devices for butterfly position. Fuel pressure and oil pressure relate to those systems, not to the mechanism that sets the butterfly’s position.