Engine Lubrication SystemsAircraft & Engines — DGCA CPL practice questions
Question 1 of 5
In a dry-sump system the scavenge pump capacity is:
All 5 questions — Engine Lubrication Systems
Aircraft & Engines · DGCA CPL. The correct option is marked on each.
Q1. In a dry-sump system the scavenge pump capacity is:
- A.Equal to the pressure pump
- B.25-50% larger than the pressure pump✓
- C.Half the pressure pump
- D.Unimportant
Why: The scavenge pump must clear oil from the sump faster than the pressure pump delivers it, so it is 25-50% larger.
Q2. As oil temperature increases, its viscosity:
- A.Increases
- B.Decreases✓
- C.Is unchanged
- D.Doubles
Why: Hot oil flows more easily (lower viscosity); the Viscosity Index describes how well the oil holds its properties over a temperature range.
Q3. 'Hydraulicing' in a radial or inverted engine refers to:
- A.Loss of oil pressure in flight
- B.Oil draining into lower cylinders causing a hydraulic lock at start✓
- C.Foaming of the oil at altitude
- D.Use of oil to drive the propeller
Why: Incompressible oil pooled in a lower cylinder can wreck the engine on start — these engines are pulled through by hand first.
Q4. Besides reducing friction, engine oil also serves to:
- A.Cool, clean, act as a hydraulic medium and indicate engine condition✓
- B.Increase compression ratio
- C.Enrich the mixture
- D.Boost magneto output
Why: Oil carries away heat and contaminants, powers items like variable-pitch propellers, and its pressure/temperature reveal engine health.
Q5. A wet-sump lubrication system stores its oil:
- A.In a separate external tank
- B.In the sump at the bottom of the engine✓
- C.In the propeller hub
- D.In the wing tanks
Why: Wet sump = oil lives in the engine sump (simple, but poor for aerobatics); dry sump = separate tank with a scavenge pump.