EASA Module 16
Piston Engine
PISTON ENGINE Tutorial Questions 2010 Definitions
Define:
To describe the nature or basic qualities of. To state the precise meaning of (a word or sense of a word).
State:
Specify in words or writing. To set forth in words; declare.
Identify:
To establish the identity of.
Itemise.
List:
Describe:
Represent in words enabling hearer or reader to form an idea of an object or process. To tell the facts, details, or particulars of something verbally or in writing.
Explain:
Make known in detail. Offer reason for cause and effect.
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EASA Module 16
16.1
1.
2. 3. 4. 5. 6.
7. 8. 9. 10. 11. 12. 13.
Piston Engine
Engine Fundamentals
Define the following terms associated with piston engine design and operation: a. Bottom dead centre (BDC). b. Top dead centre (TDC). c. Clearance volume. d. Stroke. e. Swept volume. f. Piston displacement and compression ratio. g. Firing order for inline, opposed, radial and V engines. h. Effective combustion. Describe what is meant by the term “heat engine”. Compare the difference between internal and external combustion engines. Define the term reciprocating engine. Describe how heat energy is converted into mechanical energy and the relationship between volume, pressure and temperature during the Otto cycle of operation. Reproduce an indicator diagram of the volume and pressure relationship of the Otto cycle of energy release and identify on the diagram the following characteristics: a. Where the intake valve opens and closes. b. Where the exhaust valve opens and closes. c. Pressure rises and falls during each stroke. d. Point of ignition and peak gas pressure. e. Where pressure falls below atmospheric. Define the terms valve lead, valve lag and valve overlap. Describe with a diagram the relationship between valve opening and piston position. State the limitations of two stroke piston engines for aeronautical use particularly where the demand is for high power capability. State the advantages that small two stroke engines have over similar sized four stroke engines. Describe the two-stroke cycle and outline the piston displacement and compression ratio. Identify where and why there has been a resurgence of two-stroke engines in small aircraft. Describe a Diesel aircraft engine and state its advantages.
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EASA Module 16
16.2
1. 2. 3. 4. 5.
6.
7. 8.
9. 10.
11. 12. 13.
14.
Piston Engine
Engine Performance
Define the terms mechanical efficiency, thermal efficiency and volumetric efficiency. State in percentage terms how heat energy is utilised or lost in a piston engine. Describe how and where heat is dissipated or lost in a piston engine. Specify the effect of compression ratio on thermal efficiency. Describe: a. Brake horsepower (BHP). b. Brake mean effective pressure (BMEP). c. Friction horsepower (FHP). d. Friction mean effective pressure (FMEP). e. Horsepower (HP) and kilowatt (KW). f. Indicated horsepower (IHP). g. Indicated mean effective pressure (IMEP). State the symptoms and causes of the following conditions: a. After firing. b. Back firing. c. Detonation. d. Pre-ignition. Describe how rich and lean mixture burn rates affect engine performance. Specify the effects that the following conditions have on the volumetric efficiency of a piston engine: a. Incorrect valve timing. b. Excessive valve clearance. c. Part-throttle operation. d. Long intake pipes of small diameter. e. Sharp bends in the induction system. f. Excessive carburettor air temperature. g. Excessive cylinder head temperature. h. Incomplete exhaust scavenging. Describe propulsive efficiency and explain the relationship of engine power output to propeller thrust. Define the following terms and state how they are measured: a. Compression ratio. b. Manifold pressure. c. Piston displacement. Describe how engine power is measured using a dynamometer. Describe the relationship of engine speed to power output. Define the following conditions giving the approximate fuel air ratios for each: a. Cruise power mixture. b. Lean best power. c. Rich best power mixture. d. Stoichiometric mixture. Explain how rich and lean mixture burn rates affect engine performance.
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EASA Module 16
Piston Engine
15. Explain how the following atmospheric or operating conditions affect piston engine performance: a. Altitude. b. Humidity. c. Barometric pressure. d. Temperature. e. Icing. f. Ram air. g. Manifold pressure. 16. Describe the following terms relating to engine power output and fuel consumption: a. Full throttle power. b. Normal rated power. c. Propeller load horsepower. d. Full throttle specific fuel consumption. e. Propeller load specific fuel consumption. 17. Specify how the number of cylinders relates to an engine’s smoothness of operation.
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EASA Module 16
16.3
1.
2.
3.
4.
5. 6.
7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Piston Engine
Engine Construction
Describe the constructional features, function, classification and material composition of engine: a. Connecting rods. b. Cylinders. c. Inlet and exhaust manifolds. d. Gudgeon pins. e. Piston rings. f. Pistons. Describe the constructional features, function and material composition of the following engine components: a. Cam followers. b. Inlet and exhaust valves/seats/guides/springs. c. Push rods. d. Rocker assemblies. e. Tappets. Describe the constructional features, function, classification and material composition of engine: a. Accessory/reduction gearboxes. b. Cam rings. c. Cam shafts. d. Crankshafts. e. Engine casings. f. Master rod. g. Plain and ball bearings. h. Typical roller bearings. Describe the cylinder and crankcase layout, and the firing order of the following types of piston engine: a. Inline. b. Opposed. c. Vee. State how the cylinders are numbered for each of the above engines. Specify the different cylinder numbering between Continental and Lycoming engines. Describe the different types of cylinder bore surfaces and the advantages, disadvantages and precautions when working with each. Specify the type of piston ring that would be assembled with each cylinder bore surface. Specify the reason for piston ring stagger. State why the under surfaces of pistons are often finned. Describe the basic practices associated with the removal and replacement of a cylinder assembly. State how ring gaps and side clearances are measured and adjusted, where permitted. State how cylinder heads and bores are normally attached. Specify why aero engines usually have two or more valve springs and how valve spring binding is prevented. Describe typical defects and their cause/rectification that may be associated with valves and valve operating mechanisms. State how valve stems may be checked for bow. Specify the purpose of valve clearance and the procedure for carrying out valve clearance adjustments on engines with camshafts. Describe the effects of excessive valve clearance on valve timing and engine performance. 5
EASA Module 16
Piston Engine
17. Describe the constructional features, function, classification, material composition and special surface treatment/preparation techniques of the following bottom-end assemblies: 18. Accessory/reduction gear boxes a. Cam shafts. b. Crankshafts. c. Counterweights. d. Vibration dampers (including torsional/dynamic). e. Engine casings. f. Sumps. g. Ball bearings including thrust bearings. h. Typical plain and roller bearings. 19. Describe the design and operation of dynamic dampers. 20. Describe the various means of propeller attachment to the crankshaft. 21. Specify where torque values may be found for the tightening of engine hardware.
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EASA Module 16
Piston Engine
16.4
Engine Fuel Systems
16.4.1
Carburettors
1. 2. 3. 4. 5. 6. 7.
8. 9.
16.4.2 1. 2.
3. 4. 5.
Describe the principles of operation and constructional features of a typical float chamber carburettor. Differentiate between downdraft and updraft configurations. Outline the basic characteristics of airflow through a carburettor venturi and how these are used in the operation of a carburettor or fuel/air-metering unit. Describe the effects of venturi size on engine performance. Specify how a throttle butterfly modifies venturi airflow characteristics at low and high power settings. Describe the principles of an air-bleed system. Describe the purpose, construction and principles of operation of the following components: a. Accelerator pump. b. Discharge nozzle. c. Float chamber. d. Float chamber vents, drains and plugs. e. Venturi. f. Main/idle jets. g. Idle mixture control systems. h. Power enrichment systems. i. Throttle valves. j. Idle cut-off systems. k. Altitude control. Describe the causes of impact, throttle and fuel ice and state the effects on engine performance. State the conditions for use of carburettor heat.
Fuel Injections Systems Describe the principles of operation and constructional features of a typical pressure injection carburettor. Describe the function and operation of: a. Acceleration system. b. Fuel-air metering forces. c. Idle system. d. Mixture control system. e. Power enrichment system (manual/airflow). Describe the principles of operation and constructional features of the Bendix RSA fuel injection system. Describe the principles of operation and constructional features of the Teledyne Continental fuel injection system. Outline a typical fuel injection system.
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EASA Module 16
6.
16.4.3 1. 2.
Piston Engine
Describe the function and operation of the following injection system components: a. Altitude mixture control. b. Fuel control unit. c. Fuel injection pump. d. Injector nozzle. e. Manifold valve. f. Venturi. g. Flow divider. h. Fuel air metering force. i. Impact tube. j. Throttle valve.
Electronic Engine Control Identify typical fuel system components and system layout. Describe the operation of engine control and fuel metering systems including electronic engine control (FADEC).
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EASA Module 16
16.5
1. 2.
3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
18. 19. 20.
Piston Engine
Starting and Ignition Systems
Describe the circuit layout and principles of operation of a battery ignition system. Specify the purpose of each of the following components in the system: a. Ignition switch. b. Capacitor. c. Cam. d. Points. e. Distributor. f. Battery. g. Spark plugs. h. Coil. Explain the limitations of battery powered ignition systems for aircraft use. Distinguish between advance/retard ignition timing. Define what is meant by the dwell angle and how it relates to magneto operation. Describe the relationship between distributor and crankshaft speed of a reciprocating engine. State how ignition leads are tested for insulation and continuity and suggest possible causes for leads to fail either of these tests. Describe the operation of a modern harness tester. State how radio interference occurs, the common sources and how interference is minimised/eliminated from aircraft ignition and electrical systems. Describe the layout of the secondary circuit and how a high-tension spark is produced at the cylinder spark plugs. State the purpose, construction and operation of a dual magneto incorporating two ignition systems. Explain why most aircraft engines have twin ignition systems. Describe the internal construction of a magneto and the purpose of internal components. Distinguish between high and low tension ignition systems, the advantages and disadvantages, and where each system is likely to be found. Describe the construction and operation of a low-tension ignition system. Show by graphical representation changes in flux density as the magnet of a magneto rotates through 360 degrees. Describe the construction and operating characteristics of an electrical starter as used on a typical piston engine, identifying the following systems: a. Booster coil. b. Impulse coupling. c. Induction vibrator. d. Shower of sparks. Describe the various types of ignition leads/harnesses and their constructional features, screening methods and how they are tested for serviceability. Identify the difference between high and low tension ignition systems and state the advantages and disadvantages of each system. Describe the construction and operation of spark plugs, including the following: a. Reach. b. Temperature classification. c. Typical spark plug constructional features. d. Gapping affects of spark plug performance.
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EASA Module 16
Piston Engine
21. Identify the following types of aero engine spark plug: a. Massive. b. Fine wire. 22. Describe the construction and functions of the following spark plug components: a. Metal shell. b. Ceramic insulator. c. Terminal contact. d. Electrode assembly including centre and ground electrodes. e. Resistor. 23. Describe what is meant by spark plug reach and how it is classified for aero engines. 24. Describe what is meant by heat range and how it is classified. 25. Specify how the polarity of current change affects spark plug operation. 26. Identify cylinder combustion characteristics from the examination of a recently removed spark plug. 27. State how a spark plug is cleaned and tested both by hand and using proprietary cleaning equipment. 28. Specify the correct gapping procedures for a spark plug using the correct tools and measuring devices. 29. Describe a spark plug that has lead fouling. 30. State the purpose, operating principles and correct usage of the follow maintenance and test equipment: a. Sparkplug cleaner and tester. b. Continuity tester. c. Megger. d. Insulation tester. e. Piston position indicator. f. Lamp and battery. g. Condenser tester.
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EASA Module 16
16.6
1.
2.
3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.
Piston Engine
Induction, Exhaust and Cooling Systems
Describe the construction and operation of the following engine systems: a. Induction system including alternate air supply. b. Exhaust system. c. Engine cooling system including air and liquid. Describe how cooling is effected in both a typical air and liquid-cooled engine. Special consideration should be given to the following: a. Arrangement and purpose of cylinder fins, baffles and deflectors. b. Air seals. c. Exhaust augmenters. d. Cowls, cowl flaps and gills. e. Panels. f. Blast tubes. g. Cooling properties of lubricating oil. h. Liquid coolants including types, characteristics and hazards. i. Water jackets. j. Radiators, pipes and connections. k. Cooling efficiency. l. Heat exchangers. State why the length of an exhaust system is important to engine operation. Describe typical exhaust attachment hardware including gaskets and the use of anti-seize compounds. Describe the constructional features and operation of typical engine induction/intake and alternate air supply systems. Describe the construction and maintenance of typical induction air filters. State the effects on engine operation of blocked, contaminated or damaged air filter elements. Specify devices for controlling the entry of hot air into the induction system, including heater shrouds and muffs. Describe the use and maintenance of flexible air hose (SCAT hose) in induction air systems. Describe the construction, features, material and operation of typical engine exhaust systems with particular regard to corrosion resistance, expansion and fabrication techniques. Identify typical defects and repair schemes for exhaust systems. Includes special welding and treatment processes. Determine safety issues associated with defective or damaged exhaust systems. Detail the construction, maintenance and pressure testing of exhaust heater shrouds. Explain typical carbon monoxide tests carried out in aircraft cockpits and cabins.
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EASA Module 16
16.7
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2. 3.
4.
5. 6.
7.
Piston Engine
Supercharging/Turbocharging
Define the following: a. Boot strapping. b. Critical altitude. c. Deck/upper deck pressure. d. Density altitude. e. Overboost. f. Overshoot. g. Rated power. Describe the construction and operating principles of a geared supercharger. Describe the construction, location and function of the following components: a. Diffuser and vanes. b. Engine gear drive. c. Impellor. d. Intercooler. e. Turbine. Describe the construction and operation of a turbocharger with particular regard to the following components and systems: a. Housings. b. Rotating assemblies. c. Bearings. d. Back plates. e. Lubrication system and protective devices. Describe the purpose and principles of supercharging and its effects on performance. Describe the construction and operating principles of a typical geared supercharger and turbosupercharger system identifying the difference between the following: a. External (turbosupercharger). b. Internal (supercharger). c. Multispeed. d. Multistage. e. Ground boosted and altitude engines. Describe the layout, construction and operation of system components and installation requirements of the following systems consisting of the: a. TCM turbocharger control system: i. Absolute pressure controller. ii. Manifold pressure relief valve. iii. Ratio controller. iv. Waste gate assembly. b. Textron-Lycoming turbocharger control: i. Density controller. ii. Differential pressure controller. iii. Waste gate assembly.
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EASA Module 16
16.8
1. 2. 3. 4.
5.
6. 7. 8. 9. 10.
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12. 13. 14.
Piston Engine
Lubricants and Fuels
Identify and state the properties and specifications of various aviation lubricants and fuels. Describe the purpose of fuel additives. Describe the precautions associated with aviation lubricants and fuels. Define the following terms in relation to piston engine fuels: a. Anti-knock additive (TEL). b. Octane rating. c. Performance number including lean and rich mixture ratings. d. Reid vapour pressure test values. e. Calorific value of fuel. f. Specific gravity. g. Volatility. h. Vapour locking. Describe the chemical makeup of aviation fuel with particular regard to the following terms: a. Aromatics. b. Iso-octane. c. Heptane. State how piston engine fuels are classified in terms of grade or performance rating. Describe what is conveyed by fuel designations such as 80/87, 100/130 in regard to lean and rich mixture operation. State the colour code identification for the common grades of fuel. State the purpose of the additive ethylene dibromide in aviation gasoline. Describe the characteristics of piston engine lubrication oil with particular reference to the following requirements: a. Friction reduction. b. Heat absorption. c. Sealing of moving components. d. Cushioning against shock loads. e. Cleaning. f. Corrosion protection. State the properties and specific uses of the following oils and additives: a. Ashless dispersant. b. Detergent. c. Hypoid and extreme pressure lubricants. d. Mineral. e. Multi viscosity. f. Synthetic. Describe the engine design and operating factors that determine the grade of oil to be used in a particular engine. Describe the SAE grading system and give examples of where the SAE grades may be used throughout the range of climatic temperatures. Define the following engine oil rating terms and state their affects on piston engine operation: a. Cloud point. b. Flash point. c. Pour point. d. Viscosity and viscosity index. e. Kinematic viscosity rating (centistokes). 13
EASA Module 16
16.9
1. 2. 3.
4.
5. 6.
Piston Engine
Lubrication Systems
Describe the operating principles and constructional features of wet and dry sump lubrication systems. State the suitability for each type of engine and how compensation may be made for aerobatic manoeuvres. Describe the following types of lubrication system, their characteristics and the advantages and disadvantages of each: a. Pressure lubrication. b. Splash lubrication. c. Spray lubrication. d. Combination system. Specify the lubrication method normally applied to the following parts of an engine: a. Valve gear. b. Pistons and cylinders. c. Crankshaft and camshaft bearings. d. Cam followers. e. Hydraulic tappets. f. Accessory drive gears and bushes/bearings. g. Turbocharger or supercharger. Describe the suitability of each system for typical engine configurations. Describe the constructional features and operation of the following lubrication system components and state where they are located within the lubrication system: a. Check valves. b. Oil cooler regulators. c. Oil coolers. d. Oil dilution subsystems. e. Oil filters. f. Oil tanks/hoppers. g. Pressure pumps. h. Relief valves. i. Scavenge pumps.
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EASA Module 16
16.10
1.
Piston Engine
Engine Indication Systems
Identify components of the following engine indication systems and describe system operation: a. Engine speed. b. Cylinder head temperature. c. Coolant temperature. d. Oil pressure and temperature. e. Exhaust gas temperature. f. Fuel pressure and flow. g. Manifold pressure.
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EASA Module 16
16.11
1.
2.
Piston Engine
Powerplant Installation
Describe the following engine mounting criteria: a. Mount design and geometry. b. Dynamic suspension. c. Tangential suspension. d. Dynafocal mounts (link and pedestal type). e. Lord mounts. f. Shock and anti variation mounts. g. Mounting pads. h. Baskets and frames. i. Mounting hardware including engine bearers and bearer mounting points. j. Stresses in engine mounts. k. Engine mounts condition assessment. l. Electrical bonding of mounts. m. Corrosion treatment of mounting structure. n. Safety precautions associated with the installation and removal of engines. o. Lifting points and lifting hardware. p. Exhausts and inlets associated with engine installation. Describe the configuration of the following powerplant installations: a. Firewalls. b. Cowlings. c. Acoustic panels. d. Engine mounts. e. Anti-vibration mounts. f. Hoses. g. Pipes. h. Feeders. i. Connectors. j. Wiring looms. k. Control cables and rods. l. Lifting points. m. Drains.
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EASA Module 16
16.12
Piston Engine
Engine Monitoring and Ground Operation
1. 2.
Explain procedures for engine starting and ground run-up. Explain inspection of engines and components to criteria, tolerances and data specified by engine manufacturer. 3. Describe how a compression test is carried out using a compression gauge and differential compression tester. 4. Detail typical ground running procedures for a single and light twin-engine. 5. Determine how the ignition system is checked for correct operation with particular regard to identifying a live or faulty magneto or faulty spark plug. State expected performance figures. 6. Explain why an RPM drop naturally occurs when one magneto is isolated. 7. Explain the requirements and procedures for a cold cylinder check. 8. From given information, diagnose faults encountered during engine starting and ground running and determine the rectification actions required. 9. Determine typical engine power output parameters and limitations by interpretation of given power charts or graphs. 10. From given information, diagnose faults and defects encountered during flight operations and determine the necessary rectification actions required. 11. Interpret performance data such as fuel pressure, oil pressure, manifold pressure and RPM. Describe adjustment procedures to correct abnormalities. 12. Describe the sequence of increasing and reducing RPM and manifold pressure on an engine fitted with a variable pitch propeller.
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EASA Module 16
16.13
1.
Piston Engine
Engine Storage and Preservation
Describe the preservation and depreservation of engines and engine accessories/system components. a. Describe the following criteria for placing engines in long and short-term storage: b. Corrosion-prevention materials. c. Corrosion-prevention compounds. d. Dehydrating agents. e. Corrosion-prevention treatments. f. Fluid draining. g. Internal preservation of crankcases and cylinders. h. Prevention of crankshaft rotation after preservation. i. Sealing and blanking. j. Inspection of stored engines. k. Ground-running periods for engines in short term or temporary storage. l. Storage in containers. m. Preservation of accessories and components. n. Depreservation.
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EASA Module 16
Piston Engine
References
1. 2. 3.
Dale Crane, “Powerplant”, Aviation Supplies and Academics, Inc., ISBN 1-56027-410-7. Jeppesen, “A&P Technician Powerplant Textbook”, Jeppesen Sanderson Inc., ISBN 0-88487-338-2. Oxford Aviation Training, "Aircraft General Knowledge 3 - Powerplant", JAA ATPL Theoretical Training Manuals, Transair.
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