Preflight Preparation and Aircraft Systems Knowledge (Reciprocating, Turbopropeller, and Turbojet/Turbofan)
This domain tests whether you understand how each powerplant type produces thrust, what its limits actually mean, and how system knowledge drives preflight decisions: fuel and oil loads, ignition checks, bleed-air configuration, and the takeoff power setting you will really use.
Reciprocating engines
- Detonation is uncontrolled, early combustion that drives up cylinder-head temperature; enrich the mixture and reduce manifold pressure to correct it. Preignition is ignition before the spark and is not cured by mixture alone.
- A turbocharged engine holds sea-level manifold pressure up to its critical altitude. Above that altitude, MP decays roughly 1 inHg per 1,000 ft, and the wastegate must be managed to avoid an overboost.
- Magnetos are independent of the electrical system. A run-up magneto drop within limits verifies both circuits before flight.
Turbopropeller engines
- In a free-turbine turboprop the gas generator (Ng) and power turbine (Np) are mechanically independent. Torque is the primary power indication, with ITT and Ng as the protective limits.
- The propeller governor sets Np; the condition lever schedules idle fuel and feather. Autofeather and negative-torque sensing protect the operating engine if the other fails.
Turbojet and turbofan engines
- N1 is the thrust parameter on most fans (EPR on some). FADEC schedules fuel to protect EGT/ITT limits and to avoid surge.
- Bleed-air extraction for air conditioning and anti-ice reduces available thrust and must be reflected in takeoff data.
Worked example
A turboprop takeoff chart shows 100% torque at sea level, with ITT limited to 850 °C. On a +35 °C day the ITT limit is reached at only 88% torque. The answer is not to keep pushing toward 100%: use the reduced-power takeoff column, recompute V speeds for that actual power, and re-verify the second-segment and obstacle-clearance gradients.
Traps
Confusing Ng with Np; treating EGT as a direct power reading rather than a limit; assuming a turbocharged engine produces sea-level MP above critical altitude; forgetting the thrust penalty of engine and wing anti-ice.