Carburetion and Mixture ControlAircraft & Engines — DGCA CPL practice questions

Question 1 of 5

Fuel is drawn from the float chamber into the airstream because the venturi creates:

A.High static pressure

B.Low static pressure

C.High fuel pressure

D.A temperature rise

All 5 questions — Carburetion and Mixture Control

Aircraft & Engines · DGCA CPL. The correct option is marked on each.

Q1. Fuel is drawn from the float chamber into the airstream because the venturi creates:
- A.High static pressure
- B.Low static pressure✓
- C.High fuel pressure
- D.A temperature rise
Why: Air accelerating through the venturi loses static pressure (Bernoulli); the pressure drop draws fuel into the airflow.
Q2. The accelerator pump prevents:
- A.A rich mixture at altitude
- B.A momentary weak mixture ('flat spot') when the throttle is opened quickly✓
- C.Carburettor icing
- D.Vapour lock
Why: Rapid throttle opening momentarily weakens the mixture; the accelerator pump injects extra fuel to bridge the hesitation.
Q3. As an aircraft climbs with no mixture adjustment, the carburettor mixture becomes:
- A.Progressively leaner
- B.Progressively richer✓
- C.Unchanged
- D.Stoichiometric
Why: The carburettor meters by volume; as density falls with altitude the same fuel mixes with less air mass — the mixture richens, so the pilot must lean.
Q4. A very rich mixture (about 10:1) is used for takeoff because:
- A.It produces maximum power
- B.The excess fuel cools the cylinder and helps prevent detonation✓
- C.It reduces fuel consumption
- D.It increases the octane rating
Why: Excess unburnt fuel has a cooling effect inside the cylinder, guarding against detonation at high power.
Q5. The chemically correct (stoichiometric) air-to-fuel ratio is approximately:
- A.10:1
- B.15:1✓
- C.17.4:1
- D.20:1
Why: About 15:1 air to fuel by weight — though engines run slightly richer for stable operation; ~17.4:1 may be used for economy cruise.