Supercharging and TurbochargingAircraft & Engines — DGCA CPL practice questions
Question 1 of 5
A turbocharger is driven by:
All 5 questions — Supercharging and Turbocharging
Aircraft & Engines · DGCA CPL. The correct option is marked on each.
Q1. A turbocharger is driven by:
- A.Gearing from the crankshaft
- B.The energy of the exhaust gases✓
- C.An electric motor
- D.Bleed air
Why: The exhaust stream spins a turbine which drives the compressor — using waste energy, unlike a crankshaft-geared supercharger.
Q2. The waste gate of a turbocharger controls boost by:
- A.Restricting the air intake
- B.Bypassing exhaust gas around the turbine✓
- C.Varying the propeller pitch
- D.Cooling the intake charge
Why: Opening the waste gate sends exhaust overboard, slowing the turbine; closing it speeds the turbine and raises manifold pressure.
Q3. As a turbocharged aircraft climbs, the automatic controller maintains manifold pressure by:
- A.Progressively opening the waste gate
- B.Progressively closing the waste gate✓
- C.Enriching the mixture
- D.Reducing RPM
Why: Thinner air requires more turbine speed, so the Absolute Pressure Controller closes the waste gate as altitude increases.
Q4. Critical altitude is the altitude at which:
- A.The engine stops
- B.The waste gate becomes fully closed and rated boost can no longer be maintained above it✓
- C.Detonation begins
- D.The propeller reaches fine pitch
Why: Above critical altitude the fully-closed waste gate can no longer hold sea-level manifold pressure, and power falls with further climb.
Q5. Density altitude is:
- A.Pressure altitude corrected for non-standard temperature✓
- B.Height above the ground
- C.Indicated altitude corrected for instrument error
- D.True altitude above sea level
Why: Density altitude — pressure altitude corrected for temperature — is what the engine and wings actually 'feel'; high values degrade performance.