This document provides an overview of aircraft engine accessories and components. It discusses the purpose of accessories as supplementary items that help fulfill functional requirements, though the equipment can function without them. Components are complimentary items that the equipment cannot function without, such as carburetors and magnetos. The document then discusses various aircraft fuel system components like fuel tanks, filters, pumps and valves in detail and how they contribute to providing a continuous, uninterrupted fuel supply to the engine.

1. AERO ENGINE ACCESSORIES INTRODUCTION A major power unit or equipment is installed with certain components and accessories for its normal function. These components and accessories cannot be defined very rigidly. There are various components and accessories under airframe, engine and electrical system.

3. Components are complimentary items of major equipment without which the equipment will not function e.g. COMPONENTS - Carburetor - Magneto - E.D.P. - Ignition Harness.

4. AIRCRAFT FUEL SYSTEM FUNCTION: To provide an un-interrupted supply of fuel to the engine driven pump at all operating conditions of the aero-engine.

5. AIRCRAFT FUEL SYSTEM

7. SIMPLE TWIN ENGINE FUEL SYSTEM

8. SIMPLE TWIN-ENGINE FUEL SYSTEM

10. FUEL TANK PRESSURISATION SYSTEM

12. AIRCRAFT FUEL SYSTEM SAFETY DEVICES AND ACCESSORIES AIR FILTER The air from the engine compressor is filtered before it enters the system; this prevents dirt affecting the operation of the pressure reducing valve or flow control valves.

13. AIRCRAFT FUEL SYSTEM SAFETY DEVICES AND ACCESSORIES PRESSURE REDUCING VALVE To reduce the compressed air pressure, which is used for pressurization of aircraft fuel tanks to a level, where it is not likely to damage the aircraft tanks and also fulfilling the pressurization requirements. Air taken from the compressor of gas turbine engine, is also used for pressurizing of fuel tanks.

14. AIRCRAFT FUEL SYSTEM SAFETY DEVICES AND ACCESSORIES SUCTION AND PRESSURE RELIEF VALVE This type of valve is fitted to both the front and rear tanks to prevent possible damage to the tank by limiting the maximum and the minimum atmospheric pressure within it.

15. AIRCRAFT FUEL SYSTEM SAFETY DEVICES AND ACCESSORIES VAPOUR RELEASE VALVE During inverted flying, air may pass in to the front tank, further, at high altitude fuel may boil. The pocket of air or vapour that results may stop fuel been transferred from other tanks especially when the aircraft is climbing. The vapour vent valve prevents this. As the liquid level in the tank falls, a float opens a vent valve and the gas is allowed to escape .

16. AIRCRAFT FUEL SYSTEM SAFETY DEVICES AND ACCESSORIES PRESSURE SENSOR UNITS Pressure sensor units are used in aircraft fuel system to indicate for empty conditions of tank. Whenever this pressure is dropped less than the pre-set pressure of this sensor, it will send an electrical signal, which will be converted to light to indicate that particular tank is empty.

17. SELECTOR AND CROSS FEED COCKS SELECTOR COCKS Selector cocks are essential to permit tank selection and to allow pipelines and components to be removed without draining the tank. CROSS FEED COCK It makes a cross feed line by allowing either engine to be fed from opposite side tanks during an emergency.

19. INVERTED FLIGHT RECUPERATOR PURPOSE: It ensures a positive feed under inverted flight conditions. CONSTRUCTION: It consists of fuel tight metal casing that houses a rubber bag. Fuel is fed into one end of the container from the low-pressure delivery pipeline to the engine; the other end of the container is fed with air from the fuel tank pressurization system. The rubber bag forms a flexible seal between fuel and air.

20. INVERTED FLIGHT RECUPERATOR

21. INVERTED FLIGHT RECUPERATOR OPERATION: During normal flight the casing is charged with low-pressure fuel at 15 PSI, which forces the lower pressure air out of the container past an air pressure relief valve set to 11 PSI. When the delivery of low pressure fuel from the tank fails as in inverted flight, the 10 PSI air pressure, acting on the outside of the rubber bag discharges the fuel stored in the recuperator, back into the engine supply line and so prolongs the normal flow. The volume of fuel so stored is usually sufficient to maintain power for at least 20 seconds. When the aircraft returns to a normal attitude the recuperator automatically recharges..

23. FUEL FLOW TRANSMITTER The fuel flow meter is generally the last item of aircraft fuel system installed in the main fuel pipeline between the tank and the engine and registers the amount of fuel consumed i.e., "litres gone". It consists of a transmitting unit, which measures the actual quantity of fuel passed through the unit and sends electrical impulses to the indicator, which makes a comparative recording.

25. TYPE OF FUEL TANKS (AS PER CONSTRUCTION) There are three types of fuel tanks as per construction: - Flexible fuel tank. - Rigid fuel tank. - Integral fuel tank.

26. TYPES OF FUEL TANKS

29. SELF-SEALING COVERING - These coverings have been developed to reduce the magnitude of a fuel leak, if for any reason the fuel tank is pierced or ruptured. - The self-sealing cover is of glass fabric or nylon fabric on the outside of the tank with cellular rubber. - This type of rubber is a material that is immediately affected by contact with fuel. - If tank leaks, the cellular rubber swells on contact with fuel and forces its way into the puncture to block the hole and reduces or stops the leak. - Minor leak may remain uncovered for some time until the self-sealing cover begins to swell and bulge on the outside.

30. CRASH-PROOF COVERING - To give some measure of protection against crash impact damage, fuel tanks may be covered by layers of woven glass fabric. - When fuel tanks are covered in this way they are called crash proof tanks.

31. BOOSTER PUMP - An electrically driven centrifugal pump mounted in the bottom of the fuel tanks in large aircraft. - Booster pumps are used to provide a positive flow of fuel under pressure to the engine for starting and to serve as an emergency backup in the event the engine-driven pump should fail. - They are also used to transfer fuel from one tank to another and to pump fuel overboard when it is being dumped. - Booster pumps maintain pressure on the fuel in the line to the engine-driven pump to prevent a vapour lock forming in these lines. - Centrifugal booster pumps have a small agitator propeller on top of the pump impeller. This agitator causes the vapours in the fuel to be released before the fuel leaves the tank.

32. BOOSTER PUMP - To ensure positive feed to the E.D.P. - To avoid air and vapour locks, specially at higher altitude. - To act as reserve pump incase of E.D.P. Failure. - To transfer fuel from tank to tank. - To prime the fuel system when the E.D.P. Is stationary .

34. FILTERS

36. EFFECT OF UN-FILTERED SUPPLY OF WORKING FLUID . Wear/ tear of fine-finished internal parts and working surfaces . System starvation (i.e. partial/ complete stoppage of fluid flow) due to restricted/ blocked fluid passages . Initially, adversely affected operation of the system causes a loss of system-performance . . Subsequently, system failure is caused due to fluid-starvation / mechanical failure.

39. GENERAL FEATURES FLOW RATE & PRESSURE RATING DEPEND ON SURFACE AREA EXPOSED TO FLOW FILTRATION CAPACITY DEPENDS ON FILTERING MEDIUM & ITS THICKNESS DIRECTION OF FLOW DEPENDS ON DESIGN FILTER

42. TYPES OF FILTERS FILTER SYSTEM DIRECTION OF FLOW FILTERING MEDIUM WORKING PRESSURE FLOW RATE LOCKHEED MICRONIC FILTER FUEL OUT TO IN 55-60 PAPER DISCS MOUNTED ON BOLT OR SHAFT - - VOKE’S FILTER OIL IN TO OUT FELT REINFORCED WIRE GAUGE 125 PSI - FUEL OUT TO IN FELT REINFORCED WIRE GAUGE 100 PSI (TYPE-A) 300 GAL/HR 250 PSI (TYPE-B) TECALEMIT FILTERS OIL OUT TO IN FELT REINFORCED WIRE GAUGE - - PUROLATOR FILTERS FUEL/ OTHER FLUIDS OUT TO IN ROLLED WIRE WOUND ON FRAME - - WIRE GAUGE FILTERS FUEL/ OIL/ AIR OUT TO IN/ IN TO OUT WIRE MESH - -

48. NEGATIVE `G' DEVICE In fighter aircrafts and those capable of performing aerobatics, a device known as negative `g' device, is included to ensure that when aircraft, in flight takes sudden change of direction or is flying inverted, the oil continues to be fed into the engine .

52. DE-AERATOR PURPOSE De-aerator separates the air from the oil by centrifuging action . OPERATION Oil emulsified with air enters the de-aerator, where the oil emulsion is centrifuged at high rpm to separate the air. The separated air, which still has suspended oil vapour, is directed back to the gear box through a butterfly valve . The oil collected on the periphery of the de-aerator housing is returned to the oil tank. The butterfly valve does not open until the de-aerator rotor speed reaches a pre-determined rpm, thus preventing the flow of oil from the de-aerator to the accessory box at lower rpm, as the centrifugal force below this rpm is not sufficient to centrifuge the oil particles fully to the collecting passage.

55. CENTRIFUGAL BREATHER PURPOSE The centrifugal breather separates the oil from air by centrifuging action. DESCRIPTION Mounted on the accessory gearbox, it rotates at 13,000 rpm at 100 % rated speed of the engine and breathes the air with suspended lubricating oil particles contained in the accessory gearbox separating the oil from the air by centrifugal action. The oil thus separated returns to the gearbox, while the air is vented out to the atmosphere through a Barostatic Valve which comes into operation only at altitudes beyond 12 km. Below this altitude, it only provides a direct venting passage.

56. Beyond 12 km altitude, the bellow contracts and closes the direct air venting passage as in this condition. The Spring Loaded Disc Valve comes into operation to vent the air out, when the differential pressure between the centrifugal chamber and the ambient pressure reaches a value of 0.12 bar. Operation of Barostatic Valve prevents excessive oil loss due to evaporation and ensures effective scavenging of oil from EAGB at high altitude. Spring Loaded Disc Valve maintains the pressure inside EAGB. CENTRIFUGAL BREATHER

57. CENTRIFUGAL BREATHER

61. GEAR TYPE PUMPS These are similar in operation to engine oil pumps, but are not regarded as being completely satisfactory when handling high octane fuel, particularly at high altitudes required by most modern aircrafts. Positive delivery pumps of this and rotary vane type are usually provided with a diaphragm operated relief valve, which maintains a constant delivery pressure irrespective of pump suction conditions. Fuel serving this pump acts also as a lubricant, because pump run dry.

62. DIAPHRAGM TYPE PUMP The pump is a self contained unit attached to the engines by a spigotted circular flange. The drive is transmitted by a rotary motion. This pump as a unit has two sets of diaphragm pumps each independently operated, having a common fuel inlet, each having separate filter.

68. GAS TURBINE ENGINES

70. ENGINE STARTERS

73. IMPULSE STARTER

77. INERTIA STARTER

80. AUXILIARY POWER UNIT (APU)

83. TURBO-AIR STARTER

84. CARTRIDGE TURBO-STARTER

86. LIQUID FUEL TURBO-STARTER Micro Turbo Noelle 180

87. LIQUID FUEL TURBO-STARTER

88. LIQUID FUEL TURBO-STARTER

90. ENGINE DAMAGE

99. PRECISION INSTRUMENTS

100. PRECISION INSTRUMENTS

101. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

102. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

103. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

104. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

105. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

106. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

107. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

108. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

109. EXAMPLES OF AIRCRAFT / ENGINE DAMAGE

110. WILL YOU TAKE RISK ? ADMINISTRATIVE BURDEN DUE TO INVESTIGATION WHEN ALL THE ABOVE ARE AT STAKE ! COST OF REPAIR OR REPLACEMENT OPERATIONAL CAPACITY & PREPAREDNESS LIFE EQUIPMENT RESOURCES FOR PRODUCTION MORALE OF PERSONNEL & CITIZENS DELAY IN MISSION NATIONAL IMAGE

120. SMALL BIRD: GREAT IMPACT

136. SAFE TAKE OFFs & LANDINGs ALWAYS