FAA Commercial Pilot Airplane (CAX)Aircraft SystemsMedium
In a turbocharged reciprocating engine, what component regulates the amount of exhaust gas that is diverted to drive the turbocharger's turbine?
- AThe propeller governor
- BThe mixture control
- CThe cabin outflow valve
- DThe waste gate
Show answer & explanationAnswer & explanation
Correct answer: D. The waste gate
The wastegate is a valve in the exhaust system that controls how much exhaust gas flows through the turbine versus overboard. By adjusting its position, the system controls turbine (and thus compressor) speed and, consequently, manifold pressure.
Why the other options are wrong
- A. The propeller governor controls RPM by adjusting blade pitch, unrelated to exhaust flow.
- B. The mixture control adjusts fuel-to-air ratio, not exhaust routing.
- C. The outflow valve regulates cabin pressure, not turbocharger boost.
Turbocharger Wastegate
A valve that controls the volume of exhaust gas routed to the turbocharger's turbine, thereby regulating manifold pressure (boost).
- Diverts excess exhaust overboard
- Controls turbine/compressor speed
- Can be fixed, manual, or automatic controller-operated
Memory trick: The wastegate wastes exhaust to keep boost in check.