Test your knowledge of the main 020 AGK topics. Answers at the end.
Questions
- State the four strokes of the Otto cycle and the position of the valves in each.
- Why does an aero engine have two magnetos? What does a magneto check verify?
- Describe the three carb-icing mechanisms and the pilot's response.
- Differentiate detonation and pre-ignition.
- State the colour and meaning of each ASI marking (white arc, green arc, yellow arc, red line).
- What happens to the ASI, altimeter and VSI with (a) pitot blockage, (b) static blockage, (c) both?
- State the rate of turn for a standard-rate (Rate 1) turn.
- Convert: True heading 060°, variation 5°W, deviation 2°E. What is the compass heading?
- What is the function of a constant-speed governor on a CSU propeller?
- Why must the gascolator be drained before every flight?
Answers
- (a) Intake (intake open, exhaust closed, piston down); (b) Compression (both closed, up); (c) Power (both closed, down, ignition); (d) Exhaust (intake closed, exhaust open, up). See §2.1.
- Redundancy (engine continues on a single magneto if one fails) and better combustion (two flame fronts = shorter burn). Mag check tests each magneto individually (R, L positions). Typical RPM drop per side ≤ 175, difference ≤ 50 (per AFM). See §2.2.
- (a) Evaporation cooling of fuel in venturi; (b) pressure cooling from venturi pressure drop; (c) impact icing in visible moisture. Action: carb heat full on. See §2.5.
- Detonation = uncontrolled combustion of residual charge ahead of the flame front; pre-ignition = ignition before the spark from a hot spot. See §2.6.
- White arc = flap range; green arc = normal cruise range; yellow arc = smooth air only; red line = Vne (never exceed). See §6.3.
- (a) Pitot blockage — ASI behaves like an altimeter (high in climb, low in descent); altimeter/VSI normal. (b) Static blockage — altimeter frozen at blockage altitude; VSI zero; ASI under-reads in climb, over-reads in descent. (c) Both — all unreliable; use alternate static. See §6.4.
- 3°/s = 360° in 2 min (Rate 1). See §7.4.
- True 060° + 5°W = 065° Magnetic; 065° − 2°E = 063° Compass. See §8.3.
- Maintains the selected RPM constant by automatically adjusting blade angle — more load (climb) → finer pitch, less load (descent) → coarser pitch. See §2.9.
- To remove water and sediment from the lowest point of the fuel system. Water is denser than avgas and collects there. Common cause of engine failure after take-off. See §3.3.
Note: These questions are a revision aid. Use the ECQB practice questions of your NAA in addition.