Volume 5 – Powerplant (JAR Ref 021 03) Table of Contents

Home , Compressor stall, Engine pressure ratio, Ram air turbine, Valve timing

CHAPTER 1

Piston Engine Operation and Construction

Introduction ...... 1-1 The Otto Cycle ...... 1-2 Induction ...... 1-2 Compression Stroke ...... 1-2 Power Stroke ...... 1-3 Exhaust Stroke...... 1-3 Ineffective Crank Angle...... 1-4 Pressure Volume Diagram...... 1-4 Valve Timing ...... 1-5 Inlet Valve (Lead/Lag)...... 1-5 Exhaust Valve (Lead/Lag)...... 1-6 Valve Overlap ...... 1-6 Ignition Timing...... 1-6 Power...... 1-7 Indicated Horsepower ...... 1-7 Friction Horsepower...... 1-7 Brake Horsepower ...... 1-7 Cylinder Arrangements ...... 1-8 Radial...... 1-9 Horizontally Opposed...... 1-9 Engine Efficiencies...... 1-10 Thermal Efficiency ...... 1-10 Mechanical Efficiency ...... 1-10 Volumetric Efficiency...... 1-10 Specific Fuel Consumption (SFC) ...... 1-10 Compression Ratio ...... 1-10 Engine Major Component Parts...... 1-11 Crankcase...... 1-11 Crankshaft...... 1-13 Connecting Rod ...... 1-14 Piston...... 1-14 Cylinder Barrel ...... 1-15 Cylinder Head ...... 1-15 Valve Operation ...... 1-17

CHAPTER 2

Piston Engine Carburation

Aviation Fuels ...... 2-1 Avgas...... 2-1 Octane Rating...... 2-1 Fuel Contamination...... 2-2 Density of Fuels ...... 2-2 Mixture Ratio...... 2-2 Exhaust Gas Temperature...... 2-4 Flame Rate ...... 2-4 Detonation...... 2-5 Pre-Ignition...... 2-6

CHAPTER 3

Piston Engine Carburettors

Introduction ...... 3-1 Simple Float Carburettor ...... 3-1 Limitations...... 3-2 Diffuser...... 3-3 Idle or Slow Running System ...... 3-4 Air Pressure Balance ...... 3-4 Accelerator Pump...... 3-5 Mixture Control...... 3-6 Needle Type Mixture Control ...... 3-6 Air Bleed Mixture Control ...... 3-7 Power Enrichment/Economiser Systems ...... 3-7 Needle Valve Enrichment...... 3-8 Back-Suction Economiser ...... 3-8 Carburettor and Intake Icing...... 3-9 Carburettor Ice Formation ...... 3-9 Throttle Ice ...... 3-10 Impact Icing...... 3-10 Carburettor Hot Air Check...... 3-10 Carburettor Intake Heating...... 3-11 Effect of Induction System Icing on Engine Performance ...... 3-11

CHAPTER 4

Piston Engine Lubrication and Cooling

Introduction ...... 4-1 Lubricating Oil Types ...... 4-1 Oil Grades...... 4-2 Multi-Grade Oils ...... 4-2 Lubrication Systems...... 4-3 Dry Sump System ...... 4-3 Wet Sump System ...... 4-4 System Components...... 4-5 Pressure Pump ...... 4-5 Coolers...... 4-5 Filters ...... 4-6 Pressure Gauge...... 4-7 Temperature Gauge...... 4-7 Oil Tank...... 4-8 Cooling...... 4-8 Cowl Flaps ...... 4-9 Cylinder Head Temperature Gauge ...... 4-10 Comparison between Liquid and Air-Cooling Systems ...... 4-10

CHAPTER 5

Ignition System

Introduction ...... 5-1 Magneto Operation ...... 5-1 Primary Circuit ...... 5-2 Secondary Circuit...... 5-2 Auxiliary Systems for Starting ...... 5-3 Impulse Coupling ...... 5-3 Induction Vibrator System (LT Coil) ...... 5-4 HT Booster Coil...... 5-4 Pre Take-Off Checks ...... 5-5 Magneto Checks ...... 5-5 Dead Cut Check...... 5-5 Single Ignition Check ...... 5-5

CHAPTER 6

Engine Operation

Propeller Inspection ...... 6-1 Basic Starting Procedure ...... 6-1 Power Changes ...... 6-2 Power Settings...... 6-2 Gauges ...... 6-3 RPM Indication...... 6-3 Mechanical Tachometer...... 6-3 Electric Tachometer ...... 6-4 Manifold Absolute Pressure Gauge (MAP) ...... 6-4 Fuel Flow and Pressure Gauges...... 6-5 Oil and Temperature Indications ...... 6-5

CHAPTER 7

Piston Engine Performance

Introduction ...... 7-1 Normally Aspirated...... 7-1 The Effects of Altitude on Performance ...... 7-1 Additional Factors that Affect Engine Performance...... 7-4 Ram Air Pressure...... 7-4 Humidity...... 7-4 Carburettor Air Temperature...... 7-4 Cruise Control...... 7-4

CHAPTER 8

Piston Engine Fuel Injection

Fuel Injection System...... 8-1 Injection Pump ...... 8-2 Electric Pump...... 8-3 Fuel/Air Control Unit...... 8-3 Fuel Manifold Valve ...... 8-4 Injector Nozzles ...... 8-5 Fuel Pressure Gauge...... 8-6 System Advantages ...... 8-6 Alternate Air Control...... 8-6

CHAPTER 9

Piston Engine Power Augmentation Systems

Introduction ...... 9-1 Compressor ...... 9-2 Supercharger ...... 9-3 Supercharger and Turbocharger Performance ...... 9-3 Turbocharger...... 9-5 Waste Gate ...... 9-7 Fixed Waste Gate ...... 9-7 Overboost Protection ...... 9-7 Manually-Operated Waste Gate...... 9-8 Waste Gate Actuator...... 9-8 Absolute Pressure Controller ...... 9-9 Variable Pressure Controller ...... 9-10 Dual Unit Controllers ...... 9-11 Triple Unit Controllers ...... 9-12 Intercooler ...... 9-13 Turbo Lag...... 9-13

CHAPTER 10

Propellers

Introduction ...... 10-1 Propeller Efficiency ...... 10-1 Fixed Pitch Propellers ...... 10-2 Fixed Pitch Propeller Disadvantages ...... 10-2 Blade Twist ...... 10-4 The Variable And Constant Speed Propeller ...... 10-4 Constant Speed Propeller Blade Positions ...... 10-5 Single-Acting Propeller...... 10-6 Low Pitch Stop or Centrifugal Latch...... 10-7 Constant Speed Unit (CSU) ...... 10-8 Single-Acting Propeller Feathering...... 10-12 Single-Acting Propeller Un-Feathering...... 10-12 Propeller Control Unit (PCU)...... 10-14 Double-Acting Propeller ...... 10-15 Double-Acting Propeller Feathering ...... 10-15 Double-Acting Propeller Un-Feathering ...... 10-16 Pitch Stops...... 10-16 Beta Range ...... 10-16 Reverse Pitch...... 10-17 Pitch Locks...... 10-17 Automatic Feathering ...... 10-18 Synchronisation System...... 10-19 Synchrophasing System ...... 10-20 Synchrophasing System Operation...... 10-20 Propeller Checks...... 10-21 Reduction Gearing ...... 10-21 Torquemeters...... 10-22

CHAPTER 11

Gas Turbine Principles of Operation

Introduction ...... 11-1 Newton’s Laws of Motion ...... 11-1 Bernoulli’s Theorem ...... 11-2 Convergent Duct ...... 11-3 Divergent Duct ...... 11-3 The Working Cycle of a Gas Turbine Engine...... 11-4 Thrust...... 11-5 Power...... 11-6 Equivalent Horsepower...... 11-6 Efficiencies...... 11-6 Specific Fuel Consumption ...... 11-6 Thermal Efficiency ...... 11-6 Propulsive Efficiency...... 11-7

CHAPTER 12

Gas Turbine Engines Types of Construction

Turbojet...... 12-1 High By-Pass Turbo Fan...... 12-2 Turboprop ...... 12-4 Turboshaft...... 12-6

CHAPTER 13

Gas Turbine Engines Air Inlet

Introduction ...... 13-1 Subsonic Air Inlet ...... 13-2 Supersonic Air Inlet...... 13-2 Operational Problems ...... 13-6

CHAPTER 14

Gas Turbine Engine Compressor

Introduction ...... 14-1 Centrifugal Compressor ...... 14-3 Axial Flow Compressor ...... 14-6 Types of Axial Flow Compressor ...... 14-10 Twin-Spool Axial Flow Compressor ...... 14-11 Turbofan (High By-Pass) Twin/Triple Spool...... 14-12 Compressor RPM Indication ...... 14-13 Diffuser ...... 14-13 Compressor Stall and Surge...... 14-14 Over-Fuelling Surge...... 14-15 Surge Control...... 14-16 Bleed Valves...... 14-16 Variable Inlet Guide Vanes ...... 14-17 Surge Envelope ...... 14-18 Causes and Indications of Stall...... 14-18

CHAPTER 15

Gas Turbine Engine Combustion Systems Introduction ...... 15-1 Combustion Process ...... 15-1 Type of System ...... 15-4 Multiple Chamber...... 15-4 Tubo-Annular or Cannular...... 15-5 Annular...... 15-6 Fuel Nozzles ...... 15-7 Vaporiser Type...... 15-7 Atomising Type ...... 15-8 Simplex ...... 15-9 Duple and Duplex...... 15-9 Spill-Type ...... 15-11 Rotary Atomiser ...... 15-11 Spray Nozzle...... 15-11

CHAPTER 16

Gas Turbine Engine Turbine Introduction ...... 16-1 Turbine Principles of Operation...... 16-3 Reaction Turbine...... 16-4 Impulse Turbine ...... 16-4 Impulse/Reaction Blades ...... 16-5 Turbine Cooling...... 16-7 Exhaust Gas Temperature ...... 16-9 Materials and Stresses...... 16-10 Shrouds...... 16-11

CHAPTER 17

Gas Turbine Engine Jet Pipe Exhaust System ...... 17-1 Variable Area Nozzles...... 17-2 Convergent/Divergent Nozzles...... 17-3 Other Designs ...... 17-4 Exhaust Noise Suppression ...... 17-5

CHAPTER 18

Gas Turbine Engine Reverse Thrust Introduction ...... 18-1 Operational Problems ...... 18-2 Reverse Thrust Systems...... 18-2 Clamshell Doors...... 18-3 External/Bucket Target Doors ...... 18-3 Blocker Doors...... 18-4 Operation and Indication ...... 18-7

CHAPTER 19

Gas Turbine Engine Internal Air System Introduction ...... 19-1 Cooling...... 19-1 Turbine Cooling...... 19-2 Sealing...... 19-3 Bearing Sealing...... 19-3 Accessory Cooling ...... 19-5 Engine Overheat (Turbine Overheat)...... 19-5

CHAPTER 20

Gas Turbine Engine Gearboxes and Lubrication Systems

Auxiliary Gearbox...... 20-1 Gearbox Arrangement ...... 20-2 Lubricating Oils ...... 20-3 Types of Systems ...... 20-3 Oil System Components ...... 20-6 Oil Tank...... 20-6 Filters ...... 20-7 Oil Pumps ...... 20-8 Relief and Bypass Valves ...... 20-9 Oil Coolers ...... 20-9 Centrifugal Breather...... 20-10 Bearings...... 20-11 Magnetic Chip Detectors...... 20-11 Indicator Chip Detector ...... 20-12 Instrumentation ...... 20-12

CHAPTER 21

Gas Turbine Engine Fuel Systems

Fuels ...... 21-1 Typical Fuel Systems...... 21-1 Low-Pressure Fuel System...... 21-3 LP Cock ...... 21-3 Low Pressure Pump...... 21-3 Fuel Heater ...... 21-3 Fuel Filter...... 21-4 High-Pressure Fuel System ...... 21-5 High Pressure Pump...... 21-5 Fuel Control Unit (FCU) ...... 21-7 High-Pressure Shut Off Valve...... 21-8 Fuel Flowmeter ...... 21-8 Pressurisation and Dump Valve...... 21-8 Fuel Injector Nozzles ...... 21-8 Fuel Control Systems...... 21-9 Controls and Indications ...... 21-11

CHAPTER 22

Gas Turbine Engine Starting and Ignition Systems

Introduction ...... 22-1 To Start A Turbine Engine...... 22-1 Air Starter...... 22-3 Electric Starter...... 22-4 Starting Controls ...... 22-4 Typical Twin-Spool Turbofan Starting Cycle ...... 22-5 Single Spool Start Cycle ...... 22-6 Ignition ...... 22-7 Igniter Plugs ...... 22-8 Ignition Modes of Operation ...... 22-9 Ground Start ...... 22-9 In-Flight Start...... 22-10 Continuous Ignition ...... 22-10 Automatic Ignition...... 22-11 Engine Start Malfunctions ...... 22-11 Wet Start ...... 22-11 Hot Start...... 22-11 Hung Start...... 22-12

CHAPTER 23

Gas Turbine Engine Electronic Engine Control

Introduction ...... 23-1 Full Authority Digital Engine Control (FADEC) ...... 23-1 Engine Control Limiters...... 23-3

CHAPTER 24

Gas Turbine Engine Performance

Static Thrust...... 24-1 Engine Thrust In-Flight...... 24-1 Thrust and Shaft Horsepower ...... 24-2 Variations of Thrust with Speed, Temperature, and Altitude ...... 24-2 Speed...... 24-3 Temperature ...... 24-3 Altitude ...... 24-4 Engine Pressure Ratio (EPR) ...... 24-5 Engine Thrust Rating ...... 24-5 Flat Rated Power ...... 24-6 Bleed Air ...... 24-7 Internal Supplies ...... 24-7 External Supplies ...... 24-7 Effects of Bleed Air Extraction...... 24-8 Thrust Augmentation...... 24-8 Afterburning ...... 24-8 Afterburning System...... 24-9 Water Injection ...... 24-10 System Operation ...... 24-11

CHAPTER 25

Powerplant Operation and Monitoring

Introduction ...... 25-1 Take-Off...... 25-1 Climb...... 25-1 Cruise ...... 25-2 Descent...... 25-2 Approach and Landing...... 25-2 Engine Idle RPM ...... 25-2 Control of Thrust/Power ...... 25-2 Engine Monitoring ...... 25-3 Engine Speed (RPM) ...... 25-3 Engine Pressure Ratio Indicator ...... 25-4 Turbine Gas Temperature...... 25-5 Oil Temperature and Pressure...... 25-6 Fuel Temperature and Pressure ...... 25-6 Vibration...... 25-6 Engine Torque ...... 25-7 Electronic Indicating Systems ...... 25-7 EICAS ...... 25-8 ECAM ...... 25-9 Warning Systems...... 25-9

CHAPTER 26

Auxiliary Power Unit (APU) and Ram Air Turbine (RAT)

Auxiliary Power Unit (APU) ...... 26-1 General Description ...... 26-2 Location ...... 26-3 Air Supply...... 26-4 Fuel Supply...... 26-4 Lubrication ...... 26-4 Starting and Ignition ...... 26-4 Cooling...... 26-4 Anti-Icing...... 26-4 Fire Detection and Extinguishing ...... 26-4 Controls and Indicators ...... 26-5 APU Shut Down ...... 26-5 Ram Air Turbine (RAT) ...... 26-6