AUXILIARY POWER UNIT GTCP331 - 250
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AUXILIARY POWER UNIT The auxiliary power unit is a self contained unit which makes the aircraft independent of external pneumatic and electrical power supply.
The APU fuel consumption with bleed air extracted and generator under load may be averaged at 441 lbs/hr. on the ground. In flight consumption is lower than consumption on the ground.
On the ground the APU:
APU RUNNING RUNNING indication is displayed displayed on the ECAM MEMO page. The basic element of the APU is the gas turbine which delivers mechanical shaft power for driving the accessory gearbox and produces bleed air for engine starting and for pneumatic system supply. It consists of three main components: .The power section has a two-stage centrifugal compressor driven by a three stage axial turbine governed to a constant speed by variation of fuel flow which is controlled by the fuel control unit (FCU) and the electronic control box (ECB). The load compressor has a single-stage centrifugal compressor directly driven by a power section and delivers bleed air to the aircraft pneumatic system, controlled by modulating modulating inlet guide vanes. vanes. The accessory gearbox is directly driven by the power section and carries the fuel control unit, lubri cation pumps, AC generator, cooling air fan and starter motor.
Provides bleed air for starting the engines at altitudes in the range of 1,000 ft. to 8,000 ft. and supplies the air conditioning system of the aircraft. It also provides electrical power to supply the aircraft electrical system. During takeoff, if optimum aircraft performance is required, the APU can supply bleed air for air conditioning and wing anti-icing, in this way avoiding engine thrust reduction caused by use of engine bleed air. In Flight the APU provides back-up power for: * electrical system (below 40,000 ft.)* air conditioning (below 20,000 ft.)* wing anti-icing (below 15,000 ft.) For APU start and operation, only electrical power (batteries, AC emergency inverter) and fuel supply at positive pressure are required. Under normal conditions APU starting is permitted throughout the operating speed range up to 25,000 f t. pressure altitude
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MODEL GTCP331 - 250
APU ENGINE
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APU ENGINE The GTCP331-250 Auxiliary Power Unit is designed to provide pneumatic supply and electrical power for the A300-600, and the A310 Airbus aircraft, both on the ground and in-flight. This capability makes it possible for new generation aircraft to use remote airfields which may not have ground power facilities. The APU may also be used to provide pneumatic bleed air to the aircraft's pneumatic system during maximum performance takeoffs. Specifically, Specifically, the APU provides compressed air for cabin air environmental control during aircraft servicing and loading, starting the main engines and aircraft de-icing. In addition the APU can also provide in-flight emergency electrical power in the event of a main engine generator fail ure. Electrical power can be provided independently of, or in combination with, pneumatic supply. Electrical power has priority in all modes of operation.
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APU DESIGN FUNCTION
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APU DESIGN FUNCTION The GTCP 331-250 Auxiliary Power Unit (APU) is a constant speed gas turbine engine that features rugged, economical state of the art design. The basic APU is comprised comprised of three major sections; the power section, load compressor section and the accessory gearbox section. The power section utilizes a single shaft, and consists of two centrifugal compressors which employ radial flow impeller wheels. A three stage turbine is provided with containment for the three axial flow wheels. The turbine also includes three stators and a single reverse flow annular combustor. The power section drives the load compressor and the accessory gearbox sections. The load compressor section consists of a single backward curved radial impeller wheel and a diffuser. Inlet air is controlled by inlet guide vanes. The load compressor shares the same inlet plenum duct with the power section. The accessory gearbox section provides gear reduction for the high speed torque of the power section and the APU's accessory components. The gearbox provides mounting drive pads for the customer furnished 90 KVA A.C. genera- tor, lubrication pressure and scavenge pumps, fuel control unit, cooling fan and the starter motor. The gearbox also serves as a reservoir for the oil lubrication system. A300/310 A300/31 0
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MODEL GTCP331 - 250
MODEL GTCP331-250
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MODEL GTCP331 - 250
APU LOCATION The GTCP331-250 Auxiliary Power Unit is located in the aircraft tail cone beneath the vertical stabilizer. The tail cone is a non-pressurized compartment arranged principally to support the APU and serve as an aerodynamic fairing. Access to the APU for installing, removing, servicing, and maintaining is provided through the large clamshell doors that are hinged to open outwardly and located on the underside of the tail cone. The access doors are approximately 16 feet above the ground level.
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APU LOCATION
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APU INSTALLATION
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GTCP331 - 250 LEFT SIDE VIEW
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GTCP331 - 250 RIGHT FRONT VIEW
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GTCP331 - 250 RIGHT AFT VIEW
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APU CONTROL
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APU CONTROL SYSTEM The APU control system consists of manual and automatic controls for starting, shutting down and maintaining the APU within safe limits during its operation. Control of the APU during all phases of its operation is primarily an automatic electronic function of the Electronic Control Box (ECB). The APU master control panel provides manual switch functions that control inlet door actuation and low pressure fuel boost pump operation. The panel also initiates the start and normal shutdown sequence. The panel is equipped with indicating lamps which are provided to monitor APU fuel supply pressure status, start, acceleration, ready to load status, and fault shutdowns. In order for the APU to be operated without constant monitoring, the protective shutdown system of the ECB is complimented by an automatic fire detection and extinguishing system. In the event of an APU fire or other emergency condition the APU can also be shutdown by pulling the fire handle; pressing the APU emergency shutdown push button located on the refueling panel; pressing the APU shutdown button located on the nose gear interphone panel or by setting and holding the fire test switch, located on the APU maintenance panel, in the UP position.
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APU CONTROL SYSTEM
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APU CONTROL PANEL AVAIL/FAULT Lights AVAIL (blue) - Illuminates when: 95% RPM is reached. APU power is available. APU RUNNING appears on ECAM MEMO page.
LO PR (amber) -Illuminates if:. APU fuel supply pressure drops below 6 PSI (MAS(MASTER Switch ON) .
FAULT (amber) Illuminates when: Air intake flap is not open within 30 seconds with APU MASTER switch selected ON. When APU automatic shutdown occurs, except initiated by APU MASTER switch. APU START Switch ON(white) -Initiates start sequence. At 7% RPM, the ignition is initiated and fuel is supplied. supplied. At 50% RPM, starter starter disengages and ON ON light extinguishes. At 95% RPM, ignition is de-energized. de-energized. ACCEL (blue) Illuminates at 7% N. Extinguishes when RPM reaches 95%. APU FUEL PUMP Switch AUTO -APU fuel pump pump operates automatically automatically if: APU MASTER switch is selected selected ON. Fuel line pressure from tank pumps is below 22 PSI. OVRD (white) -APU fuel pump operates continuously with APU MASTER switch selected ON. MTT For Training Purposes Only
APU MASTER MASTER SW Controls basic power supply for APU starting, operation and protection. ON. Control and protection systems energize. Fuel isolation valve opens. APU FUEL PUMP arms or activates BAT line contactors close Start system is armed In flight, if gear is up, the air intake flap opens. OFF APU shutdown initiates. If the APU bleed air has been used, the shutdown is delayed 60 seconds to allow for a cooling period. Fuel isolation valve closes. APU FUEL PUMP, PUMP, starting control and protection systems de-energize. When gear is up. the air intake flap closes 60 seconds after N drops below 7%. Resets APU circuit after automatic shutdown.
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APU MASTER SWITCH
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APU MAINTENANCE PANEL 1. Oil quantity Oil quantity is indicated in U.S. quarts. Below 60% RPM the oil quantity indication is static. Above the indication it becomes dynamic. 2. RPM Indication The RPM is indicated in percent of nominal speed. Active when MASTER SW SW is selected ON, de-activated de-activated 60 seconds after the APU speed is below 7% RPM. 3. EGT Indication Exhaust gas temperature at turbine exit is indicated in degrees Celsius. Active when MASTER SW is selected ON, deactivated 60 seconds after the APU speed is below 7% . The signal is attenuated during start. 4. HOUR METER The indicator totalizes the APU operating time when above 95% RPM 5. ISOL VALVE Indication Position of the fuel supply isolation valve is indicated by OPEN or SHUT White lights. 6. ECB BITE DISPLAY MFA Stores ECB faults leading to an APU automatic shutdown.
7. START CTL M.F.A. Stores start contactors failures. 8. FLAP CTL M.F.A. Stores air intake flap malfunctions. 9.FLAP CTL TEST Pushbutton When pressed in for 30 seconds, intake flap sequence. 10.AUTO EXITING TEST RESET Switch. Test is to be performed on ground on: TEST: Switch must be held during test SW must be selected ON. APU FIRE warning, auto extinguishing shutdown circuits are tested. The OK White light comes on to indicate a successful test. NOTE: If in operation, the APU shuts down. RESET: Test circuit is reset. Neutral: Test circuit is not energized. 11. AUTO EXITING OK Light Comes on White when auto extinguishing sequence is completed and test results positive.
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APU MAINTENENCE PANEL
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POWER CONTROL The electronic control box (ECB) is primarily a full authority digital electronic APU Controller that performs the bulk of the APU system logic for all modes of engine operation including self-testing, shutdown protection and continuous monitoring of essential APU parameters as follows:
Speed is monitored according to bleed air demand:
Sequence of start Monitoring of start Monitoring of speed (RPM) Monitoring of operating temperature (EGT) Sequence of stopping Automatic stop Monitoring of bled air
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ELECTRONIC CONTROL BOX
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APU FIRE HANDLE NOTE
1. APU FIRE HANDLE (red, latched in) Illuminate under the same conditions as stated for ENG 1(2) FIRE handle. Accompanied by LOOP lights illumination.
All these functions are electrically actuated. actuated. Extinguishes LOOP A and B lights. Illuminates AGENT SQUIB light indicating extinguisher circuits armed. The aural warning (CRC) silences.
ON GROUND accompanied by: Activation of the nose gear bay external horn. The APU FIRE light on the nose gear interphone panel. Automatic shutdown shutdown and extinguishing sequence after a time delay.
2. SQUIB TEST Switch The functions are identical to the engine SQUIB TEST Switch (2 squibs, 1 bottle).
PULLED The APU shuts down and isolates all systems: systems: Fuel (APU LP VAL VE and isolation valve close). Pneumatics (APU BLEED valve, and X FEED valve close).
3. AGENT Switch The functions are identical to the engine AGENT Switches (2 squibs, 1 bottle). 4. LOOP A (B) Switches The functions are identical to the engine LOOP Switches.
NOTE
The X FEED valve does not close if X FEED valve is MAN selected in-line.
5. LOOP LOOP TES TEST T Swit Switch ch The functions are identical to the engine LOOP TEST Switches (2 squibs, 1 bottle).
Electrical (APU generator line contactor opens). NOTE
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During APU LOOP TEST, automatic shutdown, extinguishing, the nose gear interphone panel APU FIRE light and the external horn are inhibited. A300/310 A300/31 0 Page 26
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APU FIRE HANDLE LOCATION
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REFUEL/DEFUEL CONTROL PANELS
NO EMERGENCY SHUTDOWN SWITCH ON THIS PANEL
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INTERPHONE PANEL - NOSE GEAR
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AIR INTAKE
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AIR INTAKE The air intake, which is detachable, is mounted on the bottom fuselage in front of FR95 by means of bolted joints.The air intake is provided with a flap which is closed when the APU is inoperative. When the APU is in operation either in flight or on the ground the flap is open, the operation of the flap is controlled by the APU MASTER SW switch 14KD. The one-piece air intake housing is a sandwichtype construction, made from NOMEX honeycomb, covered with reinforced fiberglass laminate, as are the air intake lip and the air intake flap. An additional sound insulating layer, made from aluminum-honeycomb aluminum-honeycomb with felt metal facing, is provided on the aluminum upper face of the leading edge and the opposite, inside face of the housing.
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AIR INTAKE COMPONENTS
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AIR INTAKE FLAP ACTUATOR DEACTIVATION/REACTIVATION The APU air intake flap actuator can be deactivated in the event it becomes inoperative and cannot be repaired immediately. immediately. DEACTIVATION a. Disconnect the plug from the connector 6039VC b. Install protective cap onto plug and secure to air intake flap. c. Manufacture a dummy connector per MM: 49-16-00. d. Install dummy connector onto receptacle 6039VC. e. Carry out manual opening of air intake flap per MM 49-16-12. f. Close applicable circuit breakers.
REACTIVATION a. Disconnect dummy connector. b. Loosen plug from air intake act\ connect to receptacle 6039VC. c. Close applicable circuit breakers d. Carry out adjustment/test of air intake system per MM 49-16-12. e. Carry out adjustment/test of air intake system per MM: 49-16-00. f. Remove Remove tag in flight flight compartm compartment. ent. g. Record reactivation in aircraft log book.
NOTE: Circuit breaker 1KB remains open and tagged until reactivation. reactivation. g. On APU maintenance panel 472VU: 1. Make certain that flap CTL MFA 65KD is off. h. On the front panel of the Electronic Control Box make certain that indicator "Inlet Door" on fault display matrix is off. i. Install Install a tag tag in the the flight flight compar compartment tment to inform inform flight flight crew that the APU is deactivated in the open position j. Make the appropriate entry in the aircraft log book.
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AIR INTAKE FLAP ACTUATOR - ELECTRICAL CONNECTION
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DRAIN SYSTEM
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POWER PLANT DRAIN SYSTEM A drain system is installed installed in the APU where it is necessary to evacuate fuel, oil, water and air. It prevents the possibly harmful accumulation of liquids in the APU bay. Water drains are run directly to the atmosphere. Fuel, oil and air drains are routed to a drain tank. The drain tank is exhausted by a suction line through the external drain mast which operates in flight at speeds above 200 knots.
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DRAIN SYSTEM
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FUEL
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APU FUEL SYSTEM General Normal fuel supply for the APU is from the left wing tanks. To use fuel from the right wing tanks, the crossfeed valve must be opened. The required positive pressure for the APU is available via tank or APU fuel pump. Fuel flow to the APU is normally controlled by the isolation valve. In case of fire, the fuel supply is interrupted by the fire shutoff valve. Fuel feed A centrifugal LP pump , installed installed in the crossfeed line, is electrically supplied by the AC EMER BUS. When the APU MASTER SW is selected to ON and : * FUEL PUMP pushbutton switch is selected AUTO: The pump is activated automatically automatically when the pressure in the supply line is below 22 PSI.
Fuel system When the tank pumps are operating, the APU pump will not operate since tank pump pressure output exceeds 22 PSI. FUEL PUMP pushbutton is in OVRD: The pump is continuously in operation. An isolation valve is installed downstream of the LP pump. When the APU is not in operation, the valve is closed to prevent the fuel line from being pressurized. A fire shut-off valve upstream of the APU compartment firewall is controlled by the APU FIRE handle (overhead panel) and on the ground by the automatic APU fire extinguishing system. The valve position is indicated by the LP VALVES APU indication on the fuel panel. The LO PR light in the FUEL PUMP pushbutton switch on the APU panel comes on when the pressure switch downstream of the fire shut-off valve senses the fuel pressure is below 6 PSI.
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FUEL SYSTEM
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APU FUEL FEED SYSTEM The APU fuel feed system obtains fuel from the l eft wing tanks via aircraft fuel system. By opening the crossfeed valve, fuel from the right tanks can be used. Fuel tank booster pumps or APU LP fuel pump 8QC supply APU fuel feed system. The APU fuel feed system consists of the APU LP fuel pump 8QC, isolation valve 11QF, fire shutoff valve 12QF, pressure switches 15QC, 2KEand fuel feed line. LP Fuel Fire Shut-Off Valve 12QF The LP fuel fire shutoff valve, located between STA 5520 (FR90) and STA5547 (FR91), isolates the APU fuel feed line in the event of an emergency. The electrically operated, spherical spherical type valve is controlled by the APU FIRE handle on APU FIRE control module 20WG or on ground by the automatic fire extinguisher system. APU LP fuel pump pump 8QC The APU LP pump is a centrifugal pump, driven by a single-phase 115 VAC motor. This motor is powered either from the normal aircraft electrical network or by the aircraft batteries via an inverter. The fuel pump is located at the rear spar of the center wing (center tank). APU LP fuel pump 8QC can can be operated via pushbutton switch 12QC to purge APU fuel feed system for maintenance purposes. Pushbutton switch 12QC is located in the APU compartment at FR 95.
Pressure switch 15 QC The pressure switch is located at the rear spar of the center wing (center tank) with LP fuel pump 8QC and isolation valve 11QF. The pressure switch activates the APU LP fuel pump 8QC i f fuel pressure in APU fuel feed line is bel ow 22 psi and APU MASTER SW switch 14KD is ON. Low Pressure Switch 2KE The low pressure switch, located between STA5502 (FR90) and STA5547 (FR91), is a differential pressure switch referenced to ambient pressure at its location in the unpressurized rear fuselage. At 6 psi or less fuel pressure in the APU fuel feed line, the low pressure switch contacts change-over and on APU main panel 429VU FUEL PUMP indicator 3QC, LO-PR comes on. APU Isolation Valve 11QF The 28 VDC electrically operated spherical plug type isolation valve located at the rear spar of the enter wing (center tank) prevents the APU fuel feed line being pressurized if APU MASTER SW switch 14 KD is OFF.
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APU FUEL FEED SYSTEM COMPONENT LOCATION
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APU FUEL FEED SYSTEM - COMPONENT LOCATION
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APU FUEL CONTROL High pressure fuel is delivered to the fuel control by the HP pump driven by the accessory gearbox. The fuel control unit operates hydromechanically hydromechanically to allow the proper amount of fuel in each operating condition; mechanical, pneumatic and electronic signals are processed by the fuel control unit. The metered fuel is injected into the combustor through two manifolds, each with nine atomizing nozzles.
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APU FUEL SYSTEM SCHEMATIC
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APU FUEL SYSTEM The APU fuel system located on the APU consists of a Fuel Control Unit (FCU), fuel flow divider, primary and secondary manifolds and nozzles. The APU fuel system provides the correct amount of fuel flow to ensure initial combustion, acceleration and on-speed governing. The actuator pressure regulator installed in the fuel control unit provides high pressure fuel to the inlet guide vane actuator for maintaining the load compressor inlet guide vanes to the bleed air demand.
Metered fuel flows through the primary and secondary fuel manifolds and is injected into the combuster by the primary and secondary fuel nozzles. To obtain optimum fuel distribution, the fuel nozzles are inserted in equally spaced positions around the combustor plenum.
Fuel Control Unit (FCU) provides metered fuel for APU operation via the flow divider to the fuel nozzles nozzles and high pressure regulated fuel to the IGV actuator. The metered fuel for APU operation and regulated high pressure fuel to the IGV actuator are analog to the received signal from the ECB. The purpose of the flow divider is to sequence and distribute fuel to the primary and secondary manifolds. Incorporated in the flow divider are built-in manifold drain valves which drain both the primary and secondary manifolds during shutdown to prevent coking of the fuel nozzles.
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APU FUEL SYSTEM
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FUEL CONTROL UNIT The fuel control unit (FCU) provides metered fuel to the flow divider in direct proportion to the signal received from the ECB. The fuel control assembly contains a fuel pump, regulators, filters, metering valve and torque motor. High pressure regulated fuel to the inlet guide vane actuator assembly is also provided by the FCU. This high pressure fuel is utilized to position and control the load compressor inlet guide vanes. Incorporated within the FCU is the fuel shutoff solenoid valve, which controls the supply of fuel. The fuel control assembly (FCU) is mounted to a flange on the forward side of the oil pump assembly. The flange on the oil pump is equipped with an alignment pin that engages into a slot on the mating flange of the FCU. This provides proper orientation and alignment of the offset drive shaft. The fuel control unit consists of an inlet section, a pump section, regulating section and metering section. Let's examine the fuel control unit one section at a time for a better understanding commencing with the inlet section.
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FUEL CONTROL UNIT
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FUEL CONTROL INLET SECTION The fuel control inlet section consists of the inlet fuel filter, differential pressure indicator and a differential pressure bypass valv valve. e. The pressure at the fuel inlet connection should be a minimum of 10 psig above fuel vapor pressure and not exceed a maximum of 55 psig. The aircraft boost pump delivers a positive supply of fuel to the pump inlet. A positive supply of fuel is necessary to prevent pump cavitation and ensure lubrication and cooling. Fuel filtration is provided by the inlet fuel filter. The element is a non-cleanable cartridge filter with a filtration rating of 10 micron nominal, 40 micron absolute. The filter element is an LRU that requires periodic replacement. A visual indication of filter contamination is provided by the incorporation of a differential pressure (Delta P) indicator. The red indicator will extend when the pressure differential across the filter exceeds 5 + 0.5 psid. The indicator may be manually reset by depressing the indicator.
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FCU INLET SECTION
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FUEL SHUTOFF VALVE The fuel shutoff valve is a normally closed, electrically opened solenoid valve. During the APU start sequence, the solenoid shutoff valve will receive a command signal from the ECB to open at seven percent rpm. On normal or fault shutdowns, the solenoid shutoff valve is commanded by the ECB to close. The fuel shutoff valve is mounted to the fuel pump assembly, to the right of the fuel torque motor, as shown here. The fuel shutoff valve is considered an LRU.
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FUEL SOLENOID S/O VALVE
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FLOW DIVIDER The purpose of the flow divider is to sequence and distribute fuel to the primary and secondary manifolds.The flow divider consists of a screen mesh inlet filter element, a start and a run sequencing valve, a primary and secondary drain valve, and a normally closed solenoid valve. The flow divider is mounted to the combustor heat shield at the eight o'clock position and is considered an LRU.
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FUEL FLOW DIVIDER SYSTEM
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FUEL MANIFOLD Metered fuel is injected into the fuel manifolds and atomizer assemblies to provide optimum fuel distribution. The primary and secondary atomizers are alternately and equally inserted in and around the combustor plenum. The primary atomizer tips are sized with a small orifice that provides proper atomization of fuel for light off. Whereas, the secondary atomizer tips are sized with a larger orifice to provide adequate fuel flow to sustain operation for acceleration on-speed governing, and variations in load. The primary and secondary atomizers are not interchangeable.
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FUEL MANIFOLD
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DRAIN VALVE A combustion chamber chamber case drain valve is provided provided to drain overboard excess fuel that would accumulate in the combustor case following following a no flame condition not attributed to fuel. The drain valve is located at the lowest point in the case to ensure complete drainage prior to another attempted start. Draining the excess fuel precludes a possible hot or torching start. The valve is normally open when the APU is not running and pressure closed when pressure reaches 9-16 psig during acceleration. Upon shutdown, the valve should open when pressure is reduced to a minimum of 5 psig. An arrow is marked valve valve on the valve body and points in the direction of flow flow overboard overboard drain line.
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DRAIN VALVE
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AIR
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BLEED AIR SYSTEM The fully automatic bleed air system supplies and controls air bleed from the load compressor for the pneumatic system. The APU bleed air system is separated from the aircraft pneumatic system by a bleed check valve and the APU load control valve. The load control valve is a shut-off butterfly valve, spring loaded, normally closed when the APU is inoperative. It is pneumatically powered and controlled by the electronic control box and the APU bleed control switch. The amount of air supplied by the APU, in accordance with aircraft system demand, is determined by the inlet guide vanes position. The position is in response to an electrical voltage signal from the electronic control box. A surge valve, installed between the compressor and the APU load control valve, ensures that sufficient air is diverted from the load compressor to maintain an adequate surge margin. Surge air flow is discharged in the tailpipe. A load compressor compressor inlet temperature sensor monitors the compressor inlet temperature as a means of sensing reverse flow. An increase of temperature, as a result of reverse flow, will initiate an APU shut down to protect the unit against damage. Additionally, the bleed air system will be monitored via the system CRT.
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AIR BLEED CONTROL SYSTEM
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BLEED AND SURGE AIR The APU bleed and surge air system provides bleed air for Main Engine Start (MES), for operating the Environmental Control System (ECS) and for the De-Icing System (De-Ice). The bleed air, which is delivered by the load compressor, is ducted to the aircraft pneumatic system via the bleed load valve. When no APU bleed air is required with APU running, the bleed load valve and Inlet Guide Vanes (IGV) are closed, and the remaining air is routed to the APU exhaust, modulated by the surge control valve.
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BLEED AIR SYSTEM
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BLEED LOAD VALVE / SURGE CONTROL VALVE Bleed Load Valve The bleed load valve is a spring loaded closed shutoff valve. It consists of a butterfly valve, pneumatic actuator, solenoid valve, position switch and a visual position indicator. When the solenoid is energized, the actuator is pressurized by 40 psig from the surge control valve regulator and opens the valve. When the solenoid is deenergized, the actuator pneumatic pressure is vented to ambient and the spring maintains the butterfly valve in the closed position. Surge Control Valve (SCV) The surge control valve is a spring loaded open, flow modulating valve and is located between the load compressor and the bleed load valve. It consists of a butterfly flap, pneumatic actuator, servo valve, torque motor, pressure regulator, pressure relief valve and a quick-dump element.
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BLEED LOAD VALVE / SURGE CONTROL VALVE
BLEED LOAD VALVE
SURGE CONTROL VALVE
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PRESSURE SENSORS Pressure Sensors The total pressure sensor is a probe, installed in the load compressor scroll. It supplies bleed air total pressure to the total pressure transducer and to the delta pressure transducer. The static pressure sensor is an annular sensor with eight sampling ports and is installed between the load compressor compressor outlet and the bleed surge duct. It provides the delta pressure transducer with static pressure. Transducers The delta pressure transducer converts the difference between the total and static pressure input into an electrical signal. It is located at the load compressor housing on the right of the APU.The total pressure transducer converts the total pressure into an electrical signal. It is located at the load compressor housing on the right side of the APU. Variable Volume Chamber The variable volume chamber avoids damaging of the transducers and acts as a shock absorber. It consists of two chambers, divided by a diaphragm and is located at the load compressor housing on the right side of the APU.
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SCV AND PCD PICKUP LOCATIONS
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INLET GUIDE VANE ACTUATOR The inlet guide vane actuator assembly controls the IGV position in response to an electrical signal from the ECB. The IGV position determines the amount of air supplied by the APU in accordance with aircraft system demands. During the APU start cycle, the IGV actuator drives and holds the inlet guide vanes closed to preclude loading the APU during acceleration. The actuator assembly is installed on the right side of the APU below the load compressor discharge port. The IGV actuator assembly is a line replaceable unit.
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INLET GUIDE VANE ACTUATOR
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COOLING FAN SYSTEM The cooling fan system, provides air to the APU compartment compartment for cooling and ventilation. The cooling air system consists of the following components: cooling fan isolation valve, cooling fan, oil cooler, and associated ducting. In operation, cooling air flows from the inlet plenum duct of the cooling fan. The fan forces the air to flow to the APU compartment cooling air outlet and through the oil cooler. Discharged air from the oil cooler is vented overboard through a series of ducts that are attached to an overboard port located in the APU access door.
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COOLING FAN SYSTEM
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INDICATION
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APU CONTROL PANEL EGT Indicator Temperature at turbine exit in °C. Active when MASTER SW is selected ON, deactivated 60 sec. after APU speed is below 7% RPM. RPM Indicator Indicated in% of nominal speed. Active when MASTER SW is selected ON, deactivated 60 sec. after APU speed is below 7% RPM. OIL QTY Indicator Below 60% RPM the oil quantity indication is static. Above the indication becomes becomes dynamic.
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APU CONTROL PANEL
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APU ECAM SYSTEM DISPLAY 1. APU GEN Load Indication (Green) The APU GEN load is given in percent. Above 110% the indication becomes Amber. The indication is replaced by a triangle (White) when the APU MASTER SW is selected OFF.
vertical scale. Above 107% the indication becomes Amber.
2. APU GEN Indication (White) The indication becomes Amber when APU GEN P/B switch is selected OFF/R and APU MASTER SW is selected ON. 3. APU GEN Voltage Indication (Green) The APU GEN Voltage is displayed in volts in digital format. Below 110 V the indication becomes Amber. Above 120 V the indication indication becomes Amber. The indication indication is replaced by OFF (White) when APU GEN P/B switch is selected OFF/R. The indication is not displayed when APU MASTER SW is in OFF position. 4. APU GEN Frequency Indication (Green) The APU GEN frequency is displayed in Hertz in digital format. Below 390 Hz the indication becomes Amber. Above 416 Hz the indication becomes Amber. The indication is not displayed when the APU MASTER SW is in the OFF position or the APU GEN P/B switch is selected OFF/R. 5. APU N% Indication (Green) The APU speed (RPM) is displayed percent on a MTT For Training Purposes Only
6. APU EGT Indication (Green) The APU Exhaust Gas Temperature is displayed in degrees Celsius on a vertical scale. Above 540oC the indication flashes. flashes. Above 585°C the the indication becomes Amber. NOTE: When the APU MASTER SW is selected OFF, the APU shut down is performed via the auto-shut down circuit for test purposes. A full scale EGT deviation is momentarily displayed, independently of the real EGT value. 7. APU FUEL PUMP Indication (White) With LO PR indication (Amber) when a fuel low pressure is detected. With PUMP OVRD (Green) when FUEL PUMP pushbutton switch is selected OVRD. There is no indication displayed in normal operation or when APU MASTER SW is selected OFF. 8. AVAIL Indication (Cyan) The indication comes on when APU RPM is greater than 95% and APU MASTER SW is selected ON. 9. APU BLEED Pressure Indication (Green) The APU BLEED pressure is displayed in PSI in digital format. Above 57 PSI the indication becomes Amber. The indication is not displayed when the bleed valve is closed. A300/310 A300/31 0
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APU
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APU RPM INDICATION The APU's electronic control unit depends on a speed signal to compute control signals for APU operation. This speed signal is provided through a monopole transducer. The speed sensor or monopole is a magnetic, non-contact variable transducer that consists of a pole piece coil assembly, magnet and transformer.
the APU speed is below 7% RPM. The RPM indicator is supplied via the time delay relay and indication relay which is controlled by the APU main relay and the 7% relay.
The monopole tip is positioned and set in close proximity of the power section bearing assembly retaining nut. The monopole produces a magnetic field, as the nut passes through the field a frequency is generated. The frequency is computed to rotational speed by the ECB. Due to the importance of the speed signal, two identical and redundant speed sensors are provided. The ECB uses the highest of the two signals generated by the monopoles. The monopoles are located on the left and right side of the APU in the air inlet plenum duct duct as depicted in the illustration above. No.1 monopole is on the right side and No.2 is on the left side of the APU. A special tool is provided to remove and install the monopoles. The monopoles are considered to be LRU's. The RPM indicator 50KN is installed on the APU maintenance panel 472VU. The indicator is active when the MASTER SW is ON, but inactive in the shutdown sequence 60 sec after
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POWER INDICATING
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APU TEMPERATURE INDICATION
Both thermocouple (TC) rakes are tested and monitored during the prestart, monitor, and self test BITE routines. The ECB monitors both TC rakes for a signal greater than -100 degrees F (-75 degrees C); additionally when speed is greater than 95 percent rpm and No.1 and No.2 TC rake signals differ by more than 150 degrees F (66.6 degrees C) the rake with the lowest signal is considered to be failed. When one TC rake is failed the APU continues to run and operates on the remaining TC rake signal, and the failed TC rake is stored in memory. Self test or fault unit interrogation will illuminate the appropriate failed "TC RAKE” RAKE” in the lower matrix. matrix. If both TC rakes have failed the APU will shutdown, fault display interrogation will illuminate "FAILED SENSOR" in the upper matrix followed by "NO 1 TC RAKE" illuminating in the lower matrix. NOTE: If a restart is attempted the start will be inhibited.
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THERMOCOUPLE HARNESS
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APU OIL LEVEL INDICATION The oil level indicating system consists of an oil level transmitter and indicator. The transmitter is installed so that it protrudes into the APU sump to monitor the sump oil level. The indicator is installed in maintenance panel 472VU and provides an indication of oil level from MIN to FULL divided into four quarters. Because, during APU running, the oil level in the sump will be less than when the APU APU is not running, the transmitter has a DYNAMIC and a STATIC operating mode.
the potential at oil transmitter. This enables the input voltage supplied to the indicator to remain at maximum so that the indicator continues to show a FULL indication.
Static Operation Mode With a full quantity of oil in the APU sump, switch 1 in the oil transmitter causes the resistance network to provide maximum input voltage to be supplied to the indicator control circuit and the indicator will show a FULL indication. As the oil level in the sump falls, switch 1 and 2 together change the value of the resistance network reducing the input voltage to the indicator control circuit, and the indicator will show a reduced indication. Dynamic Operation Mode With a full quantity of oil in the APU sump when the APU starts to run, the oil circulates throughout the APU lubrication system and the oil level in the sump falls. As the APU reaches 60% of its full running speed, a relay relay energizes and switches switches A300/310 A300/31 0
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APU MAINTENANCE PANEL
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OIL
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OIL SYSTEM The APU utilizes an integral independent lubrication system for lubrication and cooling the APU, accessory gearbox and oil cooled generator. The oil level indicating system consists of an oil level transmitter and indicator. The transmitter is installed into the sump oil level. The indicator is installed on lateral panel and provides an indication of oil level from MIN to FULL divided into four quarters. Because, during APU running, the oil level in the sump will be less than when the APU is not running, the transmitter has a dynamic and a static operating mode, provided by a 60% relay.
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OIL SYSTEM
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OIL SYSTEM The APU oil system is a wet sump design with an internal and external system and a monitoring/indication system. The internal. system consists of the oil reservoir, which is integrated in the gearbox, the oil pump assembly with oil filter element, magnetic drain plug, generator scavenge pump with oil filter element, turbine bearing scavenge pump, and the normally closed (NC) solenoid valve (de-oil). The external system consists of the oil cooler with attached thermal bypass valve and required tubing. The monitoring/indication system includes the remote oil level indication with an indicator on the APU maintenance panel 472VU and high oil temperature/low oil pressure monitoring. High oil temperature below oil pressure parameters are monitored by and, in case of fault, indicated on the Electronic Control Box (ECB) 59KD. An APU AUTO SHUT DOWN occurs in case of high oil temperature/low oil pressure and is indicated on the LH ECAM display unit. The ECB also gives a fault signal to the FAULT light on the APU overhead panel 429VU and to the MASTER CAUTION lights.
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OIL SYSTEM
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APU OIL SYSTEM The APU oil system provides lubrication and cooling to the APU modules, which are power section, load compressor and gearbox with accessories, as well as to the oil cooled auxiliary AC AC generator. The APU oil system is a wet sump design with an internal and external system and a monitoring/indication system. The internal system consists of the oil reservoir, which is integrated in the gearbox, the oil pump assembly with oil filter element, magnetic drain plug, generator scavenge pump with oil filter element, turbine bearing scavenge pump, the normally closed (NC) solenoid valve (de-oil) and several valves. The external system is the oil cooler with attached thermal bypass valve and required tubing. The monitoring/indication system includes the remote oil level indication with an indicator on the APU maintenance panel 472VU and high oil temperature/low oil pressure monitoring. High oil temperature/low oil pressure parameters are monitored by and, in case of fault, indicated on the Electronic Control Box (ECB) 59KD. An APU auto shutdown occurs in case of high oi l temperature/low oil pressure and is indicated on the LH ECAM display unit. The ECB also gives a fault signal to the FAULT light on the APU overhead panel 429VU and to the MASTER CAUTION lights.
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OIL SYSTEM SCHEMATIC
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OIL SYSTEM
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OIL PUMP The oil pump is used to supply lubricating oil under pressure to the engine gears, bearings and accessories, accessories, then return the oil to the gearcase.The oil pump is a 2 element (one pressure, one scavenge) positive displacement gear pump. The oil pump contains the pressure pump, scavenge pump, filter element, oil pressure relief valve, oil pressure regulating valve, differential pressure indicator and provisions for mounting the fuel control unit. The pump is a positive displacement gear type pump, capable of pumping 12 gpm when the APU speed is at 100 percent (7,902) rpm. The lubrication pump assembly is mounted on, and spline driven from the gearbox. The oil transfer tubes allow oil to flow into and out of the pump assembly. The forward end of the pump provides a mounting flange and drive for the fuel control unit assembly.
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LUBRICATION PUMP ASSEMBLY
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APU OIL Oil flowing from the oil cooler assembly is filtered before it is distributed throughout the lubrication system. system. The oil filter element contains fiberglass filtering material reinforced with a pleated wire mesh screen. The filter element is a non-reuseable element and is rated at 10 micron nominal and 25 micron absolute. The filter system is equipped with a Delta Pressure indicator that provides a visual indication when the filter element becomes contaminated. The Delta Pressure indicator button is retracted when the oil is flowing freely through the filter element. When the Delta p across the filter element exceeds 20 + 5 psid, a red indicator button is extended. The extended button can be manually reset. A mechanical thermal lockout incorporated within the indicator prevents the indicator from extending when oil temperature is cold and a high Delta Pressure is temporarily sensed across the element. The oil temperature must be above 46 + 14 degrees C (115 degrees + 25 degrees F) for the indicator to function.
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OIL FILTER ASSY / DELTA P INDICATOR
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GENERATOR SCAVENGE SYSTEM A generator scavenge system system is provided to return oil from the customer furnished 90 KVA oil cooled generator to the gearbox reservoir. The scavenge system consists of a scavenge pump and a filter assembly. The generator scavenge pump is a positive displacement gear type pump capable of scavenging oil at a rate of 7.5 gpm when rotating at a speed of 8360 rpm at 100 percent. The pump is mounted inside the generator drive pad cavity and driven by a gear on the generator output drive shaft. The generator scavenge pump is considered to be an LRU. Scavenged oil is is filtered by the the generator filter assembly which is mounted to the gearbox module. Two transfer tubes allow oil to flow into and out of the filter assembly.
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GENERATOR SCAVENGE SYSTEM
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OIL COOLING Oil cooling is accomplished by using an air/oil heat exchanger with airflow supplied by the gearbox driven cooling fan. The oil cooler is designed to maintain the operating oil temperature below 305+7 degrees F (151.6 degrees C). Nominal operating oil temperature is approximately 150 degrees F above ambient temperature. The oil coolers thermal bypass valve is an integral part of the oil cooler assembly and is not considered to be a line replaceable component, however, however, the oil cooler assembly is an LRU.
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OIL COOLER LOCATION
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OIL SERVICING WARNING LABEL An oil servicing warning label is affixed to the left side of the inlet plenum duct adjacent to the sight gage. The label points out that the oil filler cap on the gravity fill port should not be removed whenever oil is hot because the oil level may be above the sight glass add mark. Non-adherence to this warning may result in personal injury if the hot engine oil splashes out of the cavity fill port. If removal of the filler cap is required; maintenance personnel should ascertain that engine oil has had sufficient time to cool after engine shutdown.
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OIL SERVICING WARNING LABEL
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STARTER AND IGNITION
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STARTING After the MASTER switch is selected ON and the LO PR light in the FUEL PUMP pushbutton switch is off, the start can be initiated by pressing the START pushbutton switch. The automatic start sequence begins: The White ON light in the START pushbutton switch comes ON. The Blue integrated indication light ACCEL comes on after the air intake has fully opened (or simultaneously if the flap is already open) and the starter motor of the APU is supplied simultaneously. simultaneously. The ignition is initiated at 7% RPM and fuel is supplied. If gear is up: The air intake opens if the MASTER switch is selected ON. If gear is down: The air intake flap is open if the MASTER switch is ON. The starter motor cuts out at 50% RPM and the white ON light in the START P/B switch goes off. The APU continues to accelerate to normal regulated speed. The Blue AVAIL light comes on, the Blue ACCEL light in the START P/B switch goes out and the ignition is terminated at 95% RPM. The combuster flame is now self sustaining. NOTE: The start is inhibited as long as the air intake flap is closed. After a shutdown the MASTER switch has to be selected OFF then ON again for resetting before every new start attempt. A300/310 A300/31 0
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STARTING SYSTEM
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START MOTOR The Start Motor is designed to accelerate the APU from start initiation through light off, and to assist the APU in reaching self sustaining speed. Starter dropout is programmed to occur at 50 percent rpm. The starter is capable of accelerating the APU without the aid of combustion to an approximate speed of 20 percent. The Start Motor is equipped with a brush wear indicator. The brush wear indicator pin will recede and not be visible when the brushes require replacement. The visible length of a new brush is 1/4 inch. The Start Motor is equipped with an overspeed burst containment cover that envelopes the commutator and armature. A drive shaft located at the front of the Start Motor provides a means of manually rotating the engine.
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APU START MOTOR
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STARTER MOTOR
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APU IGNITION SYSTEM The APU Ignition System provides an effective high energy spark for light off during the start cycle, from 7 to 95 percent rpm. Activation of the ignition system until 95 percent rpm provides a relight capability in the event of a blow-out. The Ignition Unit is a high energy unit that converts 28 VDC into a high voltage of approximately 18,000 volts which is conducted to the Ignition Plug by the Ignition Lead. This high energy producing unit was selected to ensure positive ignition under all operating conditions including prolonged cold soak, up to 25,000 feet. The Ignition Unit is located on the right side of the APU, and is mounted to the mid-frame mid-frame directly behind the inlet plenum. The Ignition Unit is considered an LRU. The ignition electrical lead is capable of transmitting 18 kv pulses per second to the igniter plug. The low resistance value of the electrical lead (0.01 ohms) ensures maximum conductivity. The lead is insulated and sealed to prevent electrical energy loss and to prevent moisture and other contaminants from entering. The lead and connectors are shielded to prevent radio interference. The igniter electrical lead is an LRU.
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APU IGNITION UNIT
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TROUBLESHOOTING
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ECB FRONT PANEL
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ECB BITE INTERROGATION PROCEDURE
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ECB BITE INTERROGATION PROCEDURE
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FAULT ISOLATION PROCEDURES - MONITORED
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APU STARTING - FAULT SYMPTOMS
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FIGURE 119
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MINIFLAG DISPLAY - INDICATION / OPERATION
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J12 PIN ASSIGNMENT
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ECB/J12 TEST CONNECTION
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