The Williams FJ44 is a Family of Small

Instituto Politécnico Nacional Escuela Superior de Ingeniería Mecánica y Eléctrica U P Ticomán Ingeniería Aeronáutica

Sistemas de Motores de Combustión Interna.

ROLLS ROYCE FJ44 ALUMNO: 

GUTIERREZ DIAZ JAVIER

PROFESOR: Adolfo Cruz Osorio

ROLLS ROYCE FJ44 The Williams R.R. FJ44 is a family of small, two-spool, turbofan engines produced by Williams International/Rolls-Royce for the light business jet market. Until the recent boom in the Very Light Jet market, the FJ44 was one of the smallest turbofans available for civilian applications. Although basically a Williams design, Rolls-Royce was brought into the project, at an early stage, to design, develop and manufacture an aircooled high-pressure (HP) turbine for the engine. The FJ44 first flew on July 12, 1988 on the Scaled Composites/Beechcraft Triumph aircraft. VARIANTS  FJ44-1A  FJ44-1AP  FJ44-2A  FJ44-2C  FJ44-3A  FJ44-4

DESIGN AND DEVELOPMENT Production started in 1992 with the 1900 lbf (8.45 kN) thrust FJ44-1A, which comprises a 20.9 in (531 mm) diameter single stage blisk fan plus a single intermediate pressure (IP) booster stage, driven by a 2

stage low pressure (LP) turbine, supercharging a single stage centrifugal high pressure (HP) compressor, driven by a single stage uncooled high pressure (HP) turbine. The combustor is an impingement cooled annular design. Fuel is delivered to the combustor through an unusual rotating fuel nozzle system, rather than the standard fuel-air mixers or vapourisers. The bypass duct runs the full length the engine. Specific fuel consumption at 1900 lbf (8.45 kN) thrust at SLS, ISA is understood to be 0.456 lb/hr/lbf. A derated version, the 1500 lbf (6.67 kN) thrust FJ44-1C has an SFC of 0.460 lb/hr/lbf. An uprated version, the 2300 lbf (10.23 kN) thrust FJ44-2A, was introduced in 1997. It has a larger 21.7 in (551 mm) diameter fan, with two additional booster stages to increase core flow. Owing to stressing considerations, the centrifugal compressor is throttled-back aerodynamically to a lower HPC pressure ratio than the -1. Other features include an exhaust mixer and an electronic fuel control unit. The 2400 lbf (10.68 kN) thrust FJ44-2C is similar to the -2A, but incorporates an integrated hydromechanical fuel control unit. Further updates include the 2004 introduction of the 2820 lbf (12.54 kN) thrust FJ44-3A, which is similar to the -2A, but features an increased diameter fan and dual channel FADEC (Full Authority Digital Engine Control) unit. The 2490 lbf (11.08 kN) thrust FJ44-3A-24 is a derated version of the -3A. In 2005, a new low end version, the FJ44-1AP, was introduced, with a 1965 lbf (8.74 kN) takeoff thrust, 5% better specific fuel consumption, and lower internal temperatures. The -1AP is similar to the -1A, except for a higher pressure ratio fan, a new combustor and LP turbine, a new full length bypass duct/exhaust mixer and a dual channel FADEC. APLICATION  Alenia Aermacchi M-345

 Beechcraft Premier I  Eviation Jets EV-20 Vantage Jet  Cessna CitationJet  Grob G180 SPn  Hawker 200

Alenia Aermacchi M-345

 Lockheed Martin RQ-3 DarkStar  Lockheed Martin Polecat  Pilatus PC-24  Piper PA-47 PiperJet  Piper PiperJet Altaire  Saab 105

Beechcraft Premier I

 Scaled Composites Proteus  Scaled Composites Triumph  SyberJet SJ30  Virgin Atlantic GlobalFlyer

SyberJet SJ30

Saab 105

ESPECIFICATIONS

Written in This Work Will Speak On engine FJ44-2c DIMENSIONS

ENGINE DESCRIPTION The FJ44-2C is a two-spool co-rotating, axial flow turbofan engine with medium bypass ratio, mixed exhaust, and high cycle pressure ratio. The engine produces a minimum of 2400 pounds of takeoff thrust, uninstalled at sea level, flat rated to an ambient temperature of 72°F

Engine control is provided by an integrate fuel control unit (IFCU). Thrust is managed through power lever input to the IFCU which is mounted to and drive by the engine gearbox. The FJ44-2C is comprised of five distinct groups: LP shaft module, fan group, core module, LP turbine group and accessory gearbox.

 The LP shaft module consists of the LP shaft, the No. 1 and No. 1.5 bearing supports, the No. 1 ball bearing, and No. 1.5 roller bearing, and No. 1 carbon seal.

 The fan group consist of the spinner, the fan rotor, the fan housing and fan stator, the 3-stage IP compressor, and the IP stator stages.

 The core module is made up of the interstage housing with integral oil tank and first reduction bevel gear, the high pressure compressor (HPC) an compressor cover, the HP shaft, pinion

gear and No.2 ball bearing, the diffuser assembly, combustor cover assembly, fuel manifold and seal assembly, fuel slinger and seal, and HP turbine nozzle and primary plate assembly, the HP turbine, and the first low pressure turbine (LPT) nozzle, including the No. 3 an No. 4 roller and seals.  The LP turbine group consists of the LP turbine module (first stage LP turbine rotor, the second stage LP turbine nozzle assembly, the second stage LP turbine rotor), rear housing, a heat exchanger, and the rear case whit exhaust mixer.  The fifth group is the accessory gearbox module and engine mounted accessories.

COMPRESSOR SYSTEM GENERAL The engine has three compressor stages:  Low pressure (LP) compressor stage.  Intermediate pressure (IP) compressor stage.  High pressure (HP) compressor stage.

These stages supply compressed air for combustion. Some other functions of the air supplied by the compressor section are:  Sealing air for oil and labyrinth seals.  Cooling air for LP an HP turbine discs. DESCRIPTION The main parts of the compressor system are:        

Spinner Fan rotor (LP axial compressor) Fan stator (LP compressor axial stator) Case assembly IP compressor rotor (axial) IP compressor stator (axial) HP compressor rotor (centrifugal) Diffuser case assembly

1. The spinner bolts onto the front of the fan rotor. The spinner shape provides a smooth airflow into the engine. The sharp point prevents accumulation of ice.

2. The fan rotor (LP axial compressor) is a 20 blade titanium blisk (blades an disc are integral). The fan is attached to the LP shaft with one nut. The fan is splined but there is no master keyway to

clock the position. 3. The fan stator is located directly behind the fan rotor. The stator is keyed into the fan case assembly. It contains 41 vanes set in an aluminum case and secured and damped with polyurethane. The ID seal on the rear side seals with the IP compressor.

4. The IP compressor rotor is a three stage axial compressor. It consist of three titanium blisk welded together to form an integral assembly. The IP compressor is installed on the LP shaft and is secured by the installation of the fan and front LP retaining nut.

5. The IP stator is comprised of three stages. The 1 st and 2nd IP stator stages are integral to the IP compressor case and forget and machined Inconel 718. This stator and case assembly is divided ino three equal circumferential segments that are bolted together to form the complete assembly. The 3rd stator is a one piece assembly made from forged and machined inconel 718. All three stages are bolted together to the interstage housing. The IP stator assembly is covered by an aerodynamic splitter fairing that divides the fan air flow into core and bypass air flows.

6. The HP compressor is a centrifugal compressor made from forged and machined titanium. It is attached to the HP shaft and is powered by a single HP turbine. The HP compressor, along with the diffuser, increase the pressure of the incoming axial compressor air before combustion.

The compressor is pressed onto the HP shaft and is secured by the installation of the fuel slinger/seal assembly, HP turbine, and the rear HP nut. These parts are locked together by curvic couplings on the rear of the HP compressor, front and back of the fuel slinger/seal, and the front of the HP turbine disc. 7. The diffuser case assembly is made from inconel 718. The diffuser forward flange bolts to the interstage housing. The rear flange is the single mounting point for all the hot section components. In addition to directing HP compressor air flow, the diffuser also houses the fuel supply tube and fuel manifold which supplys fuel to the fuel slinger/seal assembly. The diffuser also has two pads on its OD which allow extraction of compressor discharge pressure (CDP) and HP bleed. The diffuser also contains ports for the igniter plugs and fuel delivery.

OPERATION A. The rotation of the compressor and turbine assemblies moves air into the engine. to

The diameter of the compressors and stators narrows from front rear. This increases the pressure and velocity of the airflows. B. The airflow goes from the fan (LP compressor) to the IP compressor. The splitter fairing, which is part of the IP stator,

divides the airflow into core air and bypass air. Core air is routed to the HP compressor and then into the diffuser. The diffuser air then enters the combustor section where it is mixed with fuel and burned. Bypass air is ducted around the core and mixes whith the exhaust. C. The LP turbines drive the fan and IP compressors. The HP turbine drives the HP compressor. The LP shaft passes through the HP shaft and connects the LP turbines with the fan and IP compressor. The HP shaft connects the HP turbine whit the HP compressor. Both shaft rotate in the same direction but not at the speed. The HP shaft speed is slightly more than twice as fast as the LP shaft speed. BYPASS DUCT GROUP GENERAL The bypass duct group includes the front bypass duct assembly, the rear bypass duct assembly, and their related parts. The function of the bypass duct group is to route a part of the air received from the fan around the core and into the exhaust. The engine air bypass-to-core ratio is 3.31:1. The bypass flow allows operation of high core temperatures and pressure, while decreasing the velocity and temperatures of the engine exhaust. DESCRIPTION A. The front bypass duct assembly is made from sheet aluminum that is formed and seam welded. Access holes for ITT probes are provided toward the aft flange. Spacer, retainers, plates, and retaining rings are used to seal the thermocouple bosses. The front ducts also houses the service adapters which supply access ports for fuel, HP bleed air, CDP air, and igniter plugs. A boss is

provided on the front duct for mounting of the fuel nozzle. Fuel drain ports are located at the bottom of the duct.

B. The rear bypass duct assembly is also made from sheet aluminum that is formed and seam welded. It also has a fuel drain port located on the bottom side of the duct. The rear duct contains a trip lever housing and cable attachment as part of the LP trip system that shuts down the engine if the shaft separates. The rear duct also includes a bracket for external mounting of the start nozzle control valve.

C. The rear mount ring is mounted ring is mounted between the front and rear bypass duct. The rear mount ball socket changes location depending on which side of the aircraft the engine is mounted on.

INTEGRAL COOLING AND SEALING DESCRIPTION AND OPERATION

AIR

SYSTEM

GENERAL Cooling air is important in maintaining the long life of the core engine parts by keeping them from getting too hot. Pressurized air is used to seal one area of the engine from another. Intermediate pressure (IP) compressor air, high pressure (HP) compressor air, and compressor discharge pressure (CDP) air are used for sealing and cooling engine areas and parts. DESCRIPTION AND OPERATION A. Air seals The primary function of the air seals is to prevent air pressure from leaking at different areas of the engine. Another function of the air seals is to vent cooling air to hot engine parts, mainly the HP and LP turbine rotors. Compressor discharge pressure (CDP) air from the diffuser is routed to the heat exchanger where it is cooled and returned via the 1st LP nozzle to the no.3 and 4 carbon seals and bearing cavities. The rest of the CDP air is routed to the LP turbine discs through integral 1st nozzle air tubes. B. Oil seals The No. 3 and No. 4 bearing cavity oil seals receive CDP sealing air through the 1st LP turbine nozzle.

C. Cooling air Cooling air from the HP compressor cools the HP nozzle (hollow) vanes, the HP turbine disc fir trees, and the fuel slinger/seal assembly. D. Breather system Sealing air is mixed with oil in the bearing cavities and is then scavenged back to the gearbox. The gearbox contains an air/oil separator to remove the air from the oil. After separation, the air is routed overboard by a breather tube.

Acceleration bleed system

GEARBOX ASSEMBLY GENERAL The gearbox assembly supplies shaft power and mounting for the engine accessories. It is bolted to the interstage housing and is located at the bottom of the engine. DESCRIPTION The gearbox assembly connects to the interstage housing and is driven off the HP shaft by an accessory drive shaft. The gearbox provides rotational power to four mount pads for accessories. These accessories are the starter/generator, FCU, the lube and scavenge pump, and the hydraulic pump. The shaft drives are oil-wetted. Magnetic carbón seals are provided at each mount pad except the lube and scavenge pump mount pad. The lube and scavenge pump mount pad uses internal passages to transfer oil to and from the gearbox assembly. The starter/generator pad i son the forward end of the gearbox. The oil pump pad is directly aft of the starter/generator pad. Drive for the starter/generator and oil pump is provided by the same drive gear. Next to the oil pad is the FCU pad. The hydraulic pad is also forward and adjacent to the starter/generator pad.

OPERATION The gearbox receives its rotational power from the HP shaft, via an accessory drive shaft. Two reduction bevel gears, one at the top and one at the bottom of the accessory drive shaft, reduce the HP shaft rotational speed for accessory operation. The gearbox provides mounting and drive provisions for the accessories. Oil wetted shafts provide lubrication for accessory shafts. The gearbox provide internal passages for the engine oil system.

FUEL SYSTEM – DESCRIPTION AND OPERATION GENERAL The purpose of the fuel system is to supply metered fuel for combustion in the engine combustion section.

DESCRIPTION A. The fuel system is made up of the following parts: 1. 2. 3. 4. 5. 6. 7. 8.

Fuel pump Fuel filter Fuel filter bypass valve Fuel control unit (FCU) Fuel manifold Fuel slinger Lube oil cooler Start Nozzle Control valve

B. The fuel pump IS made of aluminum and is mounted to the gearbox. The fuel pump uses two pump elements in a single housing. One element, at the pump inlet, is a radial flow impeller called the boost stage. The second element is a gear type, positive displacement pump called pressure stage. Both elements are driven by a single gearbox drive coupling. The FCU is mounted to the fuel pump and receives fuel through internal passages.

C. The fuel filter is contained in a stainless steel bowl that is housing. The filter is located between the boost Pump and the gear pump from any fuel tank contaminants. The fuel filter element is 30 micron.

D. The fuel filter electrical indicator (delta P switch) is installed on the fuel pump. It allows fuel to continue to flow into the gear pump if the differential pressure between the filter inlet and outlet passages reaches 10 psid. Ehen 4.5 psid is present annunciator light in the cockpit will illuminate, indicating impending bypass. The lamp will remain illuminated until differential pressure drops below 1.5 psid.

E. Fuel control unit

F. The start nozzle control valve controls the flow of fuel from the P2´port of the fuel control unit to the start fuel nozzle. The maximum cracking pressure for the valve is 85 psid (P2’ - Pamb) and the minimum closing pressure is 55 psid. The valve flows a minimum of 7 pph of fuel at 35 psid. The max flow limit is 18 pph.

G. The engine has 3 fixed "OW, stationary fuel nozzle for improved altitude re-start reliability. This nozzle provides approximately 9 pph of additional fuel flow, continuously, during all engine operation. The nozzle receives high pressure (P2) metered fuel from the fuel control unit, via the start nozzle control valve.

H. The fuel manifold supplies fiel to the fuel slinger in the combustion section. The manifold tube goes through the front bypass duct by way of the right section. The service island ' and enters the diffuser case. The manifold supplies fuel to the underside of the rotating fuel slinger.

I. The fuel slinger is located on the HP shaft between the combustor cover and the primary plate. It is part of the seal and fuel slinger assembly. Fuel is supplied to the -under side of the slinger by the fuel manifold. The fuel is ejected radially outward into the combustion zone through a series of holes in the slinger.

J. The lube oil cooler is a fuel/oil heat exchanger mounted on the engine gearbox. It uses fuel from the fuel control to cool engine oil.

K. Hydromechanical control unit.

OPERATION Fuel enters the fuel pump where it is filtered, then pressurized, and moved to the FCU through internal passages in the pump and FCU. The fuel leaves the FCU and enters the oil cooler. From the oil cooler, the fuel passes through the fuel flow meter then enters the core engine through the fuel manifold tube. A last chance filter is located in the manifold tube. The manifold tube follows the contour of the diffuser and opens up into a cavity which forms the ID of the diffuser. Here the fuel is supplied to the underside of the fuel slinger. The fuel slinger, which rotates with the HP rotary group, ejects the fuel radially through a series of delivery holes where it is sprayed directly into the combustion zone.

Additional fuel for engine relight is continuously supplied from the FCU to the start control nozzle control valve. The fuel is then routed to the fuel nozzle where is sprayed directly into the combustion zone. FUEL SHUTDOWN A. A fuel shutoff valve, which is controlled by power lever movement, provides the normal means for engine shutdown. B. A mechanical LP shaft separation detection device, mounted on the engine, will detect LP shaft rearward movement of 0.050 inch or greater. This safety device will prevent an LP Turbine rotor aver speed condition, and possible turbine burst, in case of LP shaft separation. It does this by automatically shutting off fuel flow to the fuel control unit via mechanical linkage.

FUEL CONTROL SYSTEM

GENERAL The fuel control unit (FCU) controls the fuel flow to the combustion section.

DESCRIPTION The FCU is a hydromechanical fuel metering unit. It provides steadystate and transient HP compressor rotor speed control. The FCU is mounted on the back side of the fuel pump which is mounted on the gearbox. The following is a list of the FCU integral components systems. 1. Metering valve 2. Fan/LP shaft separation lever

3. Pressure and shutoff valve 4. Acceleration and deceleration schedules 5. Motive flow valve 6. HP relief valve 7. TT2 bias of max N2 8. Thrust lever angle input shaft 9. Acceleration bleed valve control 10. Start nozzle fuel supply OPERATION Thrust setting is operated by the airframe thrust lever linkage connection to the FCU power lever angle (PLA) input shaft. The thrust lever shaft supports two functions: activation of PLA shutoff valve below 15° PLA, and scheduling of steady-stage governing speed between 18 and 90° PLA. The PLA shutoff valve, when fully depressed (PLA≤3°), ports fuel pump high pressure discharge flow back to boost. System pressure is reduced, which allows the pressure and shutoff valve to close. The pressurizing and shutoff valve, which is springloaded in the closed direction, provides a minimum back pressure of 200 psi to the FCU during operation and, when in shutdown, provides a drop tight seal to prevent fuel from flowing to the engine.

FUEL SYSTEM

IGNITION SYSTEM

GENERAL The ignition system supplies spark to ignite the fuel/air mixture in the combustor. DESCRIPTION A.    B.

The ignition system is made up of the following parts: Ignition Exciters (2) Igniter Leads (2) Igniter Plugs (2 The two ignition exciters are high energy, capacitive discharge devices. The parts for each ignition exciter are contained in a corrosion resistant, case which is sealed against air. Both ignition exciter cases are mounted to the engine interstage housing. The spark rate is one to six sparks per channel, per second. The exciters can operate continuously with input voltage ranging from 10 to 30 volts, 3.5 Joules stored energy.

C. The igniter leads are made from a low-loss coaxial cable which is designed for use at 18 to 24 Kv. The right and left leads are different lengths.

D. The igniter plugs are sealed against air and have precious metal electrodes. The igniter plug case is made of high temperature, corrosion resistant alloys.

OPERATION

The ignition switch in the cockpit activates the ignition exciters. The ignition exciters draw current from the battery and sends current through each igniter lead, independently, at a rate of one to six sparks per second. The igniter plugs ignite the fuel/air mixture in the combustor. Igniters continue to fire until the ignition switch is turned off.

Ignition system

AIR SYSTEM – DESCRIPTION AND OPERATION GENERAL The FJ44 is a two spool, axial flow, bypass turbofan the engine has three compressors: a low pressure (LP) axial compressor, and a high pressure engine. The bypass ratio is 3.3: 1. (LP) axial compressor, and high pressure (HP) centrifugal compressor. The LP compressor (fan) and IP compressor are driven by two LP turbines. The HP compressor is driven by a single HP turbine. When the mixture of fuel and compressed air is ignited in the combustor section, the expanding gases drive the turbines.

A. Bypass Principal. The bypass principal lets part of the air passing through the fan bypass the PP compressor, HP compressor, combustion section and HP and LP turbines. This permits the engine to use high cyclic temperatures and pressures and still produce a low jet exhaust velocity. Bypass air also decreases the velocity and temperature of the exhaust gases. This combination creates high thermal efficiency and high propulsive efficiency. In addition, the bypass air decreases the noise level and increases the power/weight ratio for a given engine thrust. B. Cooling Air Cooling air comes from the HP compressor at the diffuser flange. It is known as compressor discharge pressure (CDP). CDP air moves through the 1st LP turbine nozzle to cool the two LP turbines. Diffused air cools the HP nozzle and the HP turbines. C. Acceleration Bleed System The acceleration bleed system is operated by the fuel control unit (FCU). The acceleration bleed cable connects the FCU with a butterfly valve in the interstage housing. The butterfly valve is open at engine start and is closed by the FCU when the engine reaches 89% to 89.3% N2. This allows unloading of the HP compressor during acceleration. D. HP Bleed The engine is equipped to provide both HP compressor and fan bleed air for aircraft use. Two HP bleed air ports are located on the forward bypass service island ahead of each igniter at the 5:30 an 7:30 0’clock positions. HP compressor bleed air can be extracted from either or both of these ports. Two fan bleed ports are located on the aft bypass

duct immediately ahead of the nozzle mounting flange and at the 3:00 an 9:00 o’clock positions.

ENGINE CONTROLS – DESCRIPTION AND OPERATION GENERAL The speed of the engine is controlled by separation, the fuel is shutoff and LP shaft separation, the fuel is shutoff to prevent the engine from an over speed condition. DESCRIPTION A. The engine control system contains the following parts: o Power Lever o LP Shaft trip Sensor B. The power lever is connected to the fuel control unit (FCU) at the power lever input shaft. The minimum and maximum speed settings are adjusted and set prior to engine installation. C. The LP shaft trip sensor is connected to the FCU fan/LP shaft separation shutoff valve by a cable that runs from the LP trip lever housing, located on the rear bypass duct, to the FCU.

OPERATION A. The power lever angle (PLA) setting in the cockpit is mechanically transferred to the FCU by a cable linkage. The PLA controls the engine speed by limiting the fuel flow from the FCU for any desired engine speed in the operating range. B. The LP shaft trip sensor is operated in the event of an LP shaft separation. This event would force the LP turbines in an aft direction against the LP trip lever. The LP trip lever is connected to a trigger mechanism on the rear bypass duct. The trigger mechanism, when tripped, pushes the LP trip sensor cable forward and shuts the engine by cutting off its fuel. This also prevents an over speed condition down.

ENGINE INDICATING – DESCRIPTION AND OPERATION GENERAL The engine indicating system monitors the condition of the engines and transmits this information to the cockpit.

DESCRIPTION A. The indicating system is made up of the following parts:

      

Gearbox magnetic speed pickup assembly (HP) LP magnetic speed pickup assembly interstage turbine temperature (ITT) probe (6) Engine vibration pickup (test equipment) Fuel filter electrical indicator switch (delta P) Oil filter differential pressure (delta P) indicator Magnetic chip collectors

B. The gearbox magnetic speed pickup is installed on the gearbox and reads the HP spool speed through the gearbox. An output frequency of 6741 Hz is produced at maximum HP shaft speed (100 percent N2). C. The LP magnetic speed pickup is installed in the interstage housing and measures speed directly from the LP shaft. The output frequency is 5174 Hz at full rotational speed (100 percent N1). D. There are six type K lTT probes located in the 1st LP turbine nozzle. The thermocouples have a long stern or a short stem, depending on the combustor profile during engine build and test. The thermocouple leads are joined and averaged at the electrical connector. The averaged temperature is then displayed in the cockpit. E. The engine vibration pickup(s) (test equipment) is attached to the interstage housing. It measures vibration levels and sends this data to the vibration analyzer.

OIL SYSTEM– DESCRIPTION AND OPERATION GENERAL A. The oil system provides lubrication for the four main shaft bearings. The accessory gearbox bearings, the gears and the drive splines. B. The oil tank and oil passages are internal to the engine except for one external oil line. DESCRIPTION A. The oil system is made up of the following parts: (1) Lube and scavenge pump (2) Oil filter (3) Oil filter bypass valve (4) Filter differential pressure (delta P) indicator (5) Lube oil cooler (6) Reservoir (oil tank) (7) Oil pressure regulator B. Lube and Scavenge Pump The lube and scavenge pump is a positive displacement pump. It includes one pressure element and two scavenge elements contained in a single housing. The inlet to each element is protected by aware mesh screen. All inlet and discharge ports are located on the pump mounting flange face to make pump replacement easier. A pressure relief valve is

located in the pump housing. This valve will keep approximately 130 140 psi pressure rise across the lube element under normal operating temperatures and flow conditions. The regulator valve also protects against over-pressurization.

C. The oil filter is a disposable cartridge that is housed in an aluminum bowl that is threaded into the gearbox housing. It is connected to the pressure pump outlet through drilled passages in the gearbox.

D. Oil filter bypass. An oil filter bypass valve is located in the gearbox housing. When differential pressure across the oil filter increases to 30 psid, the valve opens. This allows oil to flow to the engine if the filter element becomes totally blocked.

E. Delta P indicator A filter differential pressure (delta P) Indicator is paralleled with the oil filter and bypass valve. As the bypass valve approaches its opening pressure, the delta P indicator pin extends to indicate excessive filter contamination. The indicator operates at 15+/- 3 psid. A thermal lockout prevents. The indicator from operating because of high delta P caused by cold oil.

F. Lube oil cooler The oil cooler is a fuel/oil heat exchanger and is made of aluminum. The oil cooler is mounted to the gearbox and transmits the oil in and out through the mounting flange faces. Fuel travels in and out through external lines. G. Oil reservoir (oil tank) 1) The oil tank is part of the interstage housing. The quantity of useable oil, allowing for 22 percent expansion space within the

tank, is approximately three (3) quarts (2.8 liters). This amount is enough for 30 hours of engine operation at the maximum engine oil consumption rate of 0.023 gallons (0.087 liters) per hour. 2) The oil internally vented earing cavities which, in turn, are vented overboard via the gearbox air-oil separator. The oil tank is serviced from the outboard side of either the right or left mounted engine configurations. H. The Oil pressure, the regulator is located on the upper right side of the interstage housing, near the right hand oil fill port. It is set at the Factory to monitor the main oil pressure of the internal passage which carries oil to the gearbox. When regulating oil returns oil to the oil tank through a separate internal passage in the interstage housing. OPERATION A. The lube and scavenge pump is driven by gearbox gear rotation. It pumps oil through the main oil filter and then to the oil cooler. The pressure oil circuit is then taken, via the oil manifold mounted in the tank, to the top of the tank. At this point a small amount of flow is bled off to the tank expansion space through a small hole. This hole acts as a syphon break between bearing cavities and the oil system oil at engine shutdown. A small amount of oil is led back to the pump to increase pump performance at altitude. The main flow divides to feed the No. 1 /No. 2 bearing cavity, and the No. 3 / No. 4 bearing cavity. The only external oil tube splits from the last chance filter before lubricating the bearings. The No. 1 I No. 2 bearing supply and feeds the gearbox oil jets. The oil passes through a last chance filter before lubricating the bearings. The No. 2 and No. 3 bearings are under-race lubricated. The No. 1 and No.4 bearings and second reduction mesh and radial drive splines are jet-lubricated. The accessory drive splines and gearbox bearings and gears are splash lubricated.

B. The forward cavity lube flow drains into the gearbox where it is scavenged. Two Scavenge elements are used to provide independent scavenging of the rear bearing cavity and the gearbox sump. Each scavenge flow is passed through a screen before passing into the scavenge pump. The screens remove particles from the oil that are large enough to damage the scavenge pump.

Oil system