UNIT III ENGINE SYSTEMS Fuel systems for Piston and jet engines, - Components of multi engines. Lubricating systems for piston and jet engines - Starting and Ignition systems - Typical examples for piston and jet Engines.

THE FUEL SYSTEM Those units and components which store and deliver fuel to the engine. Includes:- Engine driven fuel pumps for reciprocating engines, includes tanks (bladder), valves, boost pumps, etc., and those components which furnish a means of dumping fuel overboard. Includes integral and tip fuel tank leak detection and sealing.

THE FUEL SYSTEM The purpose of the fuel system is to provide reliably the proper amount of clean fuel at the right pressure to the engines during all phases of flight and during all maneuvers. The fuel system includes • Fuel storage (tanks, components for tank ventilation, over-wing filler necks and caps) • Fuel distribution (all components from the filler to the tank and from the tank to the engine quick disconnect: plumbing, pumps, valves, and controls) • Fuel dump (all components used to dump fuel overboard during flight) • Indicating (all components used to indicate the quantity, temperature, and pressure of the fuel)

REQUIREMENTS OF FUEL SYSTEM 1. Fuel system is to deliver a uniform flow of clean fuel under constant pressure 2. Fuel supply must be adequate to meet all engine demands at various altitudes and attitudes of flight. 3. Employ gravity feed or pressure feed systems. 4. Unusable fuel is available for use when the aircraft is in steepest climb or in any reasonable maneuver. 5. Each fuel system must be constructed to ensure fuel flow at a rate and pressure established for proper engine. 6. Fuel systems and components must be tested under actual or simulated operating conditions

TYPES OF FUEL SYSTEM Types: 1. Aircraft fuel system 2. Engine fuel system Aircraft fuel system: Begins with the fuel tank and ends at the engine fuel system. Engine fuel system: Includes engine driven pumps and the fuel metering devices.

TYPES OF FUEL SYSTEMS Fuel systems can be classified in two broad categories: Gravity-Feed Systems Pressure-Feed Systems

GRAVITY-FEED SYSTEMS Gravity-Feed Systems use only the force of gravity to push fuel to the engine fuel-control mechanism The bottom of the fuel tank must be high enough to provide adequate pressure to the fuel-control component This type of system is often used in high-wing light aircraft

PRESSURE-FEED SYSTEMS Pressure-Feed Systems require the use of a fuel pump to provide fuel-pressure to the engine’s fuel-control component There are two main reasons these systems are necessary: The fuel tanks are too low to provide enough pressure from gravity The fuel tanks are a great distance from the engine Also, most large aircraft with higher powered engines require a pressure system regardless of the fuel tank location because of the large volume of fuel used by the engines

FUEL SYSTEM COMPONENTS Pumps Tanks Lines Valves Fuel Flow-meters Filters and Strainers Quantity Indicators Warning Components Fuel Drains Heaters

FUEL-PUMP REQUIREMENTS Engine fuel systems require main pumps and in some systems emergency pumps These requirements depend on the type of engines installed on the aircraft

RECIPROCATING-ENGINE FUEL-PUMP REQUIREMENTS Reciprocating-engines which are not gravity-fed require: At least one main pump for each engine These pumps must be engine-driven The pump capacity must capable of providing enough fuel flow for all operations

TURBINE-ENGINE FUEL-PUMP REQUIREMENTS Turbine-Engines require: At least one main pump for each engine Main pump power supply must be independent of all other main pump power supplies Each positive-displacement main pump must be able to be bypassed

Turbine-Engine Fuel-Pump Requirements (cont.) Turbine-engines also require emergency pumps The emergency pump must be immediately available to supply fuel to the engine in the event of a main pump failure Emergency pump power supplies must be independent of that of the corresponding main pump If both the emergency and main pumps operate continuously, there must be some means of alerting the flight crew of a failure of either pump

FUEL TANKS Fuel systems on different aircraft may use several types of fuel tanks The three basic types of fuel tanks used on aircraft are: Integral Rigid Removable Bladder

INTEGRAL FUEL TANKS Integral Fuel Tanks are commonly located in the aircraft’s wings or fuselage These tanks are ones that are built into the structure of the aircraft and generally can not be removed Integral Fuel Tanks are formed by the actual structure of the aircraft The seams are sealed, usually with synthetic rubber, to produce an area inside the aircraft structure which will contain the fuel This type of tank is used in some light high-performance aircraft and turbine-powered transports

RIGID REMOVABLE FUEL TANKS Rigid removable fuel tanks are often made of aluminum components that are welded together These tanks are installed in compartments specifically made for the tank The tanks may be held in place with padded straps This type of tank is often found on more expensive light aircraft and reciprocating-engine-powered transports

BLADDER TYPE FUEL TANKS Bladder type fuel tanks are basically a reinforced rubberized bag These tanks are installed in compartments which support the weight of the fuel The tank is held in place with buttons or snaps on the bottom and sides of the tank This type of tank is usually found on light aircraft and some turboprop and turbine-powered aircraft

FUEL LINES Fuel lines on aircraft are either made of rigid metal tubing or flexible hose Most of the fuel lines are the rigid type which are usually made of aluminum alloys The flexible hose fuel lines are either made of synthetic rubber or Teflon The diameter of tubing used is decided by the engine’s fuel requirements

VALVES Fuel selector valves are used in aircraft fuel systems to: Shut off fuel flow Cross-feed Transfer fuel Selector valves may be operated manually or electrically depending on the installation

FILTERS AND STRAINERS Removes moisture and other sediments that might be in the system Fuel is usually strained at three points in the system Through a finger or bootstrap strainer in the bottom of the fuel tank Through a master strainer which is usually located at the lowest point in the system

Fuel system of MULTI ENGINE aircraft components Fuel pump Delivers a continues supply of fuel at proper pressure at all times of operation Contact displacement Variable displacement

FUEL HEATER Fuel are susceptible for formation of ice in the fuel filters when the fuel is up to 32”F or less than that The main function of the fuel heater is to protect the engine fuel system from ice formation

FUEL FILTER Micron Wafer Plain screen mesh filter Placed between fuel tank and engine fuel system Protects the engine driven pump and various control devices Mainly from contaminations Types are Micron Wafer Plain screen mesh filter

FUEL SPRAY NOZZLE It injects fuel to the combustion area for burning the fuel completely Prevents the formation of any hot spot on combustion chamber Types are Simplex Duplex

FUEL DIVIDER It is fitted inside the Duplex Nozzle. It is the integral part of Duplex Nozzle It divides the primary and secondary fuel supplies by providing proper spray at all fuel flows.

FUEL PRESSURE AND DUMP VALVE Same as flow divider During engine operation it divides metered fuel into two portions , primary and secondary At engine shutdown it provides a dump system which connects the fuel manifolds to an overboard drain

DRAIN VALVES Used to drain the fuel from various components of the engine where accumulated fuel is most likely to present operation problems In some instance the fuel manifold are drained by an individual unit known as drip/Dump valve

FUEL QUANTITY INDICATOR Fuel pressure Gauge Fuel temperature Gauge Fuel flow meter Fuel selector valve/control valve/shut of valve