Turbine Engines
A B2 systems-level overview: the Brayton cycle and gas path, engine types and spools, and electronic engine control (EEC/FADEC).
Turbine engines — summary notes
Free- The gas turbine works on the continuous-flow Brayton cycle — intake, compressor, combustor, turbine, exhaust — and produces thrust by Newton's third law, F = ṁ·(V_jet − V_inlet): a mass of air is accelerated rearward.
- Engine types differ only in where the energy goes: turbojet (all thrust from the jet), turbofan (most thrust from the bypass fan — quiet and efficient), turboprop (most power to a propeller) and turboshaft (all power to an output shaft).
- Modern engines are multi-spool: the low-pressure spool (N1 — fan/LP compressor + LP turbine) and the high-pressure spool (N2 — HP compressor + HP turbine) run at their own speeds; the gas generator supplies gas to drive the fan/power turbine.
- For the B2 (avionics) technician the engine is essentially a controlled, instrumented system: an ELECTRONIC ENGINE CONTROL (EEC)/FADEC reads the sensors and schedules the fuel and start sequence, so the B2 focus is the sensors, wiring, connectors and the EEC — not the internal mechanical detail covered in Module 15.
- The parameters the aircraft systems set and watch are engine speed (N1/N2), gas temperature (EGT/ITT), thrust (EPR or N1) and fuel flow, plus oil and vibration.
- ⚠ Exam trap: a turbofan makes most of its thrust from the BYPASS fan, not the core jet; and the FADEC/EEC is a full-authority ELECTRONIC controller that schedules fuel — the B2 syllabus treats the engine at systems/indicating level, not the deep mechanical detail of Module 15.
- Thrust
- F = ṁ·(V_jet − V_inlet)
From a B2 (avionics) standpoint, what does 'FADEC' do and what does the technician mainly work on?
FADEC (Full Authority Digital Engine Control) is the electronic engine controller: it reads engine sensors (speeds, temperatures, pressures, throttle) and has full authority to schedule fuel flow, the start sequence and limit protection. The B2 technician deals with the electrical/electronic side — the sensors, harnesses, connectors, the EEC unit and the indicating channels — rather than the internal gas-path hardware.
Gas turbine — the running turbojet
FreeTurbine engines concept map
FreeTurbine Engines (B2)
Turbine engines quiz
FreeTurbine Engines — quiz
1. A gas turbine operates on which cycle?
2. Thrust is produced by:
3. A turbofan produces most of its thrust from the:
4. The gas-path order in a gas turbine is:
5. On a two-spool engine, N1 refers to the:
6. FADEC stands for:
7. The EEC/FADEC schedules the engine's:
8. A turboshaft engine delivers its output as: