Training Manual B /400/500 ATA 49 APS ATA 104 Level 3. Lufthansa Technical Training GmbH Lufthansa Base

Transcription

1 Training Manual B /400/500 ATA 49 APS 2000 ATA 104 Level 3 Book No: B L3 E APS Lufthansa Technical Training GmbH Lufthansa Base Lufthansa

2 For training purposes and internal use only. Copyright by Lufthansa Technical Training GmbH. All rights reserved. No parts of this training manual may be sold or reproduced in any form without permission of: Lufthansa Technical Training GmbH Lufthansa Base Frankfurt D Frankfurt/Main Tel / Fax / Lufthansa Base Hamburg Weg beim Jäger 193 D Hamburg Tel / Fax /

3 TABLE OF CONTENTS ATA 49 APU APS 2000 INTRODUCTION PANEL DESCRIPTION ACCESS DOOR APU DRAINS AIR INLET DESCRIPTION APU AIR INLET ADJUSTMENTS BOROSCOPE INSPECTION APU LUBRICATION SYSTEM OIL TANK DESCRIPTION COMPONENT DESCRIPTION OIL TANK SERVICING OIL SYSTEM SCHEMATIC DESCRIPTION APU FUEL SYSTEM APU FUEL SHUTOFF VALVE FUEL HEATER ELECTRONIC FUEL CONTROL AND PUMP ASSEMBLY 34 START PURGE VALVE FUEL SYSTEM OPERATION DRY MOTOR THE APU WET MOTOR THE APU LOW PRESSURE BLEED APU AIR SYSTEM APU BLEED BLEED AIR VALVE BLEED AIR VALVE OPERATION APU COOLING AIR SYSTEM APU COOLING AIR COOLING FAN IGNITION AND START SYSTEM IGNITION COMPONENT DESCRIPTION STARTING COMPONENT DESCRIPTION STARTING COMPONENT DESCRIPTION APU CONTROLS APU CONTROL UNIT/FADEC DESCRIPTION FADEC DESCRIPTION AMBIENT PRESSURE TRANSDUCER SPEED SENSOR APU START SEQUENCE APU SHUT DOWNS E. G. T. INDICATING SYSTEM THERMOCOUPLES ( 2 ) EGT BALANCING RESISTOR ID-MODULE FADEC BITE CODES AND LIGHTS MCDU, APU DATA PAGES TROUBLE SHOOTING APU OPERATION LIMITS AND PARAMETERS APU OPERATION TEST Page: i

4 TABLE OF FIGURES Figure 1 APS Figure 2 APU Panel Figure 3 APU Access Door and Shroud Figure 4 Shroud Drains Figure 5 APU Air Inlet Figure 6 APU Air Inlet Adjustments Figure 7 Boroscope Inspection Figure 8 Lubrication Schematic Figure 9 Lubrication System Components Figure 10 Lubrication System Components Figure 11 Oil Tank Servicing Figure 12 Oil Servicing System Schematic Figure 13 Fuel System Schematic Figure 14 APU Fuel Shutoff Valve and DC Fuel Boost Pump Figure 15 APU Fuel Shutoff Valve Control Figure 16 DC Fuel Boost Pump Control Figure 17 Fuel Heater and Flow Control Valve Figure 18 Fuel Control and Pump Assembly Figure 19 Fuel System Components Figure 20 APU-MAX. EGT CHART Figure 21 APU Dry Motoring Figure 22 APU Wet Motoring Figure 23 Low Pressure Bleed Figure 24 Bleed Air Schematic Figure 25 APU Bleed Air Components Figure 26 APU Bleed Air Valve Schematic Figure 27 APU Cooling Air Schematic Figure 28 Cooling Air Components Figure 29 Cooling Air Shutoff Valve Figure 30 Ignition / Starting Schematic Figure 31 Ignition Components Figure 32 Start Relay Location Figure 33 Starter Motor and Shaft Assembly Figure 34 APU Control Sytem Schematic Figure 35 APU Control Unit and FADEC Component Figure 36 FADEC Component Figure 37 Amb. Press. Transducer and Amb. Temp. Sensor Figure 38 Speed Sensor Figure 39 APU Start Sequence Figure 40 Normal/Auto Shut Down Figure 41 EGT Schematic Figure 42 Thermocouples and Event Monitoring Unit Figure 43 APU E. G. T. System Schematic Figure 44 EGT Balancing Resistor and Indicator Figure 45 ID-Module Figure 46 LOP FADEC Bite Code Indication Figure 47 MCDU APU DATA Display Figure 48 LOP FADEC BITE Code Shown Figure 49 LOP FADEC BITE Code Shown Page: ii

5 GENERAL ATA 49 APU FWD 49 APS 2000 FRA US/Egz Page: 1

6 GENERAL APS 2000 INTRODUCTION The APS 2000 auxillary power unit (APU) supplies electrical and pneumatic power to other airplane systems. This permits these airplane systems to operate without the use of ground power sources or the engines. The APU can also supply electrical and pneumatic power in the air. Altitude Operational Limits The APU can supply: 55 KVA electrical power on ground 45 KVA electrical power up to 37,000 feet (11,277 meters) Electrical and pneumatic power is available at the same time up to 10,000 feet (3,048 meters). Pneumatic power alone is available up to 17,000 feet (5,183 meters). The APU can be started at 37,000 feet or below. Model Designation: Manufacturer: Sundstrand Power System, San Diego, USA. Ratings at SL: ROTOR SPEED 45,225 RPM steady state OVERSPEED 105% / 47,486 OUTPUT SPEED 6000 RPM at Generator Drive BLEED AIR FLOW 193 lbs/min at no electrical load BLEED AIR PRESSURE 45 PSIG BLEED AIR TEMP 209 C FUEL FLOW 200 kg/h during max load at standard day MAX CONTINUOUS EGT 702 C Max EGT 730 C Abreviations and Acronyms APU Auxilary Power Unit ARINC Aeronautical Radio Inc. BATT Battery BITE Built in Test Equipment C Degrees/Celsius CB Circuit Breaker DC Direct Current DMU Data Managment Unit EGT Exhaust Gas Temperature EMU Event Monitoring Unit FADEC Full Authority Digital Electronic Controller LBS Pounds HZ Hertz KG Kilogram KVA Kilo Volt Ampere KW Kilowatt LCD Liquid Crystal Display LRU Line Replaceable Unit MCDU Multi Purpose Control Display Unit PPH Pounds Per Hour PSI Punds Per Square Inch PSIA Punds Per Square Inch Absolute PSID Punds Per Square Inch Differential PSIG Punds Per Square Inch Gage RPM Revolutions Per Minute RTD Resistive Temperature Detector SHP Shaft Horsepower SW Switch V Volts FRA US/E gz Page: 2

7 GENERAL Figure 1 APS 2000 FRA US/E gz Page: 3

8 GENERAL PANEL DESCRIPTION MAINTENANCE LIGHT ( blue ) ON- Identifies an APU Warning. An Electrical fault has occured, or an APU Oil Servicing is required. See MCDU Multi purpuse Control Display Unit or FADEC Fault Display for Maintenance Light Reason. APU BLEED AIR SWITCH ON -Opens the APU Bleed Air Valve if the APU is Operating. OFF- Closes the APU Bleed Air Valve LOW OIL PRESSURE LIGHT (amber) ON- APU oil pressure is low, causing the APU to initiate an automatic shutdown (after the start cycle is complete). Light is illuminated during start until APU oil pressure is normal. Light is armed only when APU switch is not in OFF. FAULT LIGHT (amber) ON- Identifies an Automatic Shutdown of the APU. See MCDU Multi purpuse Control Display Unit or FADEC Fault Display for Fault Light Reason.APU oil temperature is excessive, causing APU to initiate an automatic shutdown. Light is armed only when APU switch is not in OFF. OVERSPEED LIGHT (amber) ON - APU speed excessive causing APU to initiate an automatic shutdown. Note: MASTER CAUTION light and the APU annunciator will illuminate together with any of the above described amber caution lights (Exception: Low oil pressure light during APU start) APU GENERATOR AC AMMETER Display APU generator load current. APU MASTER CONTROL SWITCH OFF- Normal position when APU is not running. OFF- when APU is running initiates normal shutdown. ON - Normal position with APU running. START (Momentary) - When APU switch is moved from OFF to START and released to ON, causes automatic start sequence to be initiated. EXHAUST TEMPERATURE INDICATOR Displays APU exhaust gas temperature. FRA US/E gz Page: 4

9 GENERAL MAINTENANCE LIGHT LOW OIL PRESSURE LIGHT FAULT LIGHT OVERSPEED LIGHT APU GENERATOR AC METER DUCT PRESSURE INDICATOR L PACK OFF AUTO HIGH PSI RECIRC FAN OFF NORMAL ISOLATION VALVE CLOSE AUTO OFF AUTO HIGH OVHT TEST R PACK FORWARD OVERHEAD PANEL, P5 APU OFF ON START APU EXHAUST GAS TEMPERATURE INDICATOR FRA US/E gz Figure 2 APU MASTER CONTOL SWITCH APU Panel WING ANTI ICE 1 PACK TRIP OFF WING-BODY OVERHEAT BLEED TRIP OFF OFF ON OPEN TRIP RESET APU BLEED PACK TRIP OFF WING-BODY OVERHEAT BLEED TRIP OFF OFF ON FORWARD OVERHEAD PANEL, P5 2 WING ANTI ICE APU BLEED AIR SWITCH Page: 5

10 POWER PLANT ACCESS DOOR Access to the APU is through an access door, completely enclosing the APU compartment. The access door is hinged on the right side and latched on the left side. It consists of skin, ribs and stringers forming the outside contour of the fuselage. On the inside are two door open holding rods, two drain cups and cooling air exhaust. On the outside, is a drain mast connected to the drain cups. The door can be opened for normal APU servicing, or it can be removed by unlatching the hinges on the right side. The drain cups should be inspected periodically for cleanliness. The exhaust ducting is cooled by four air inlets around the aft end of the exhaust fairing /400/ SHROUD The APU shroud is a titanium compartment that fully protects the APU power plant. The APU shroud gives the protection from an APU fire and decrease the noise from the APU power plant. The APU shroud includes the upper shroud and the lower shroud. The upper shroud attaches to the airplane structure and holds the forward end of the APU exhaust duct. The upper shroud and the lower shroud connect to one another with the shroud latches on the lower shroud. Upper Shroud The upper shroud is installed in the APU compartment. When the APU is removed from the airplane, the upper shroud will stay in the APU compartment. The upper shroud has openings for the fuel lines, air inlet ducts and bleed air duct. Three mounting brackets for the APU engine attach to the shroud rings. Lower Shroud The lower shroud attaches to the upper shroud with ten shroud latches. The lower shroud has the openings to the filler port for the oil tank and to the overboard exhaust for the APU cooling air. Also, there is an access panel that is removed to read the elapsed time indicator. When the lower shroud is removed, you can get access to do maintenance on the APU. FRA US8 hs Page: 6

11 POWER PLANT /400/ EXHAUST DUCT UPPER SHROUD APU DOOR HINGE ( 2 LOCATIONS ) DRAIN SEAL PLATES DOOR SUPPORT RODS (STOWED POSITION) APU SHROUD LATCH ( 10 LOCATIONS ) APU ACCESS DOOR APU COOLING AIR TO DRAIN MAST EXHAUST DUCT FRA US8 hs APU DOOR LATCH (3 PLACES) Figure 3 FWD DRAIN HOLES DRAIN LINE APU Access Door and Shroud. COOLING AIR EXHAUST LOWER SHROUD DRAIN FITTING FWD Page: 7

12 APU POWER PLANT APU DRAINS The APU drains provide means for draining unburned fuel from the engine and for draining fuel or oil from the shroud in event of leakage inside the shroud. At the aft end of the shroud, a drain cup with stand-pipe picks up unburned fuel discharged through the turbine exhaust port. Two fuel drain lines are manifolded into a fitting on the engine. This fitting mates with a drain cup in the drain line. The drain line terminates at a fitting at the forward end of the shroud. Adjacent to the drain line terminal end fitting is another fitting. Through this fitting fuel or oil is drained from the shroud. Both fittings at the forward end of the shroud mate with drain cups in the APU compartment access door. The drain cups in the access door are connected to a drain mast. B /430/ Drain Valve The drain valve is a spring- loaded ball device. The drain valve permits fuel that collects in the combustor to flow to the APU drain mast. The drain valve is located at the lowest point in the combustor plenum. This permits complete drainage prior to another attempted start. The drain valve is spring-ioaded open until the APU reaches approximately 15 percent RPM. At 15 % RPM APU combustor pressure closes the drain valve. FRA TS83 hs Page: 8

13 APU POWER PLANT APU ENGINE B /430/ FWD TURBINE EXHAUST END DRAIN LOWER SHROUD DRAIN CHECK VALVE DRAIN RESERVIOR TURBINE EXHAUST END DRAIN CUP SHROUD DRAIN SHROUD DRAIN CUP DRAIN CUP FRA TS83 hs APU ACCESS DOOR APU DRAIN MAST Figure 4 Shroud Drains. A Page: 9

14 APU AIR INLET AIR INLET DESCRIPTION The air supply for the APU engine operation and accessories cooling is through a door installed in the air inlet duct. The air inlet consists of a door with a vortex generator and flap, actuator, door position switch and ducting. Access to the actuator and door position switch is through an access door on the left side of the fuselage, forward of the APU compartment Operation When the actuator is powered, the pushrods move the door to the open position. Movement of the door deflects the flap on the vortex generator for improvement of air flow into the inlet. When the door is fully open, the door switch operates. The switch actuation is part of the APU start cycle. FRA US/T hs Page: 10

15 APU AIR INLET APU COMPARTMENT STRUCTURE TORQUE BOX AIR DIFFUSER DUCT COMPRESSOR AIR DUCT COOLING AIR DUCT VORTEX GENERATOR AIR INLET DOOR FWD AIR INLET DOOR AIR DIFFUSER DUCT FRA US/T hs INLET DOOR POSITION SWITCH ACTUATOR ARM Figure 5 APU Air Inlet AIR INLET DOOR ACTUATOR FWD Page: 11

16 APU AIR INLET APU AIR INLET ADJUSTMENTS Maintenance Practices The APU air inlet has three adjustments: Air Inlet Door Adjustment. Door alignment. Adjustment is made by varying the length of the two actuator push rods Air Inlet Door Position Switch Adjustment. Door open switch, door full open position. Adjustment is made by two nuts on the switch. Vortex Generator Flap Adjustment. Flap deflection with door open. Adjustment is made by varying the length of the control rod and the adjustable flap stop. FRA US/E gz Page: 12

17 APU AIR INLET AIR INLET DOOR (CLOSED POSITION) AIR INLET DOOR (OPEN POSITION) VORTEX GENERATOR FLAP SET SCREW (DOOR OPEN) VORTEX GENERATOR FWD FLAP STOP 3 (DOOR CLOSED POSITION) 3 PUSHROD FLAP STOP (DOOR OPEN POSITION) INBD DOOR CLOSE BARREL FITTING NUT NO. 1 NUT NO. 2 AIR INLET DOOR - CLOSED POSITION AIR INLET DOOR ACTUATOR FRA US/E gz DOOR OPEN 1 PUSHROD BEARING END Figure 6 APU Air Inlet Adjustments 2 AIR INLET DOOR AIR DIFFUSER DUCT NUT DOOR POSITION SWITCH Page: 13

18 ENGINE BOROSCOPE INSPECTION The following components of the turbine assembly may be inspected by the use of a boroscope: Turbine Blade Tips Combustion Chamber Turbine Nozzle Vanes Turbine Wheel Blades Compressor Wheel Blades Compressor Diffuser Legend: 4. BLADES OF THE COMPRESSOR WHEEL 5. LEADlNG EDGE OF THE COMPRESSOR WHEEL 6. EXHAUST SECTlON 7. BLADES AND VANES OF THE TURBlNE WHEEL 8. LEADlNG EDGE OF THE TURBlNE WHEEL (3 LOCATlONS) 9. COMBUSTION CHAMBER (4 LOCATlONS) 10.HAND-CRANK PROVlSlONS (LOCATED ON THE COOLlNG FAN) FRA US/E gz Page: 14

19 ENGINE COMPRESSOR WHEEL TURBINE NOZZLE FWD FWD 3 4 BOROSCOPE PLUG COVER PLATE COMPRESSOR PLENUM IGNITER PLUG HAND-CRANK PROVISIONS COVER LEGEND: COMPRESSOR DIFFUSER BLADES OF THE COMPRESSOR WHEEL 5 6 TURBINE WHEEL COMBUSTION CHAMBER BOLT MANUAL DRIVE FRA US/E gz Figure 7 COOLING AIR FAN LEADING EDGE OF THE COMPRESSOR WHEEL EXHAUST SECTION BLADES AND VANES OF THE TURBINE WHEEL LEADING EDGE OF THE TURBINE WHEEL (3 LOCATIONS) COMBUSTION Boroscope Inspection CHAMBER Page: 15

20 OIL APU LUBRICATION SYSTEM The APS 2000 is lubricated by a self-contained, wet sump system that is integral with the gearbox. The oil system provides a pressurized supply of oil that lubricates and cools all the gears and bearings in the gearbox and engine rotor assembly Operation Before the APU is started, the de-prime valve is energized to the open position. This stops the supply of oil to the oil pump. When the APU accelerates to 55% service speed, the de-prime valve is de-energized to the closed position. The oil pump pulls the oil from the oil tank and sends the oil to the oil filter element. If the oil filter element is clogged, the bypass valve opens to permit the oil fiow to continue. From the oil filter element, the oil goes through the oil cooler. If the oil cooler is clogged, the bypass valve for the oil cooler opens. From the oil cooler, the oil goes to the gearbox assembly and the gears and bearings of the APU engine. In the gears and bearings of the APU engine, an airloil mixture is made. The air/oil mixture is divided when the gearshaft turns. The air is sent to the turbine exhaust port through a gearbox case vent. The oil returns to the oil tank by gravity. The Iube service panel replenishes the oil tank with the oil. The ADD Iight (amber Iight) on the Iube service panei comes on when the oil quantity in the oil tank is 1.6 U,S quarts (l.5 Iiters). When the ADD Iight is on, a solenoid valve opens to Iet the oil enter the oil tank from the pressure fiii connection. The FULL Iight (green Iight) comes on when the oil quantity in the oil tank is 2.6 U.S quarts (2.5 Iiters). The solenoid valve wiii close when the FULL Iight is on. The solenoid valve closes so the oil tank wiii receive the correct amount of oil. Gearbox oil distribution Oil is drawn from the gearbox sump by the oil pump mounted on the front of the gearbox. The oil is filtered prior to leaving the pump and then fiows through the oil cooler. The cooled oil is returned to the gearbox oil passages and jets to provide Iubrication and cooling of the gears, shafts and bearings. During operation of the gear system, an oil/air mist is created inside the gearbox. The oil and air are separated by the action of a mechanical separator that is part of the generator gear shaft. Oil is returned by gravity to the gearbox oil sump and the air is vented to the APU exhaust through the gearbox vent system. FRA US/E hs Page: 16

21 OIL OIL PRESSURE SWITCH < 20 PSI ON > 26 PSI OFF ÈÈÈÈÈÈÈÈÈÈÈÈÈÈ È ÈÈ È ÈÈ È ÈÈ GEARBOX LUBE RELIEF VALVE 45 PSID ROTOR ASSEMBLY OIL TANK VENT LINE TO APU EXHAUST FORWARD OVERHEAD PANEL, P5 FULL ADD APU OIL TANK OIL TYPE FILL WHEN AMBER LIGHT IS ON ÉÉÉ LUBE SERVICING PANEL APU OIL QTY MODULE OIL TANK SOLENOID VALVE PRESS. FILL CONNECTION FRA US/E hs S FADEC AFT CARGO CPTM OIL COOLER BYPASS VALVE PSID HIGH OIL TEMP. SW. È ÈÈ OIL È COOLER ÈÈ È ÈÈ È ÈÈ È ÈÈ È ÈÈ È ÈÈ È ÈÈ È ÈÈ È È È ÈÈÈÈ COOLING AIR FAN OIL FILTER AND PUMP ASSEMBLY OIL FILTER BYPASS VALVE PSID OIL PUMP TO DE-PRIME 60 PSI VALVE < 55 % OPEN OIL FILTER OIL FILTER > 55% CLOSE CLOGGING IND PSID C Figure 8 È Lubrication Schematic GEARBOX DE-PRIME VALVE S FROM FADEC OILTANK OIL LEVEL SENSOR SIGHT GLASS MAGNETIC DRAIN PLUG ÉÉ ÉÉ ÉÉ AIR/OIL MIST TURBINE ASSEMBLY FILLER CAP LEGEND OIL SUCTION OIL PRESSURE OIL PRESS. FILLING OIL TANK VENT LINE Page: 17

22 OIL OIL TANK DESCRIPTION Oil Tank The oil tank is part of the gearbox assembly. The oil tank hold the supply of oil for the APU Iubrication system. The oil is removed from the oil tank by the oil pump. The oil goes through the oil filter element and oil cooler to the gearbox assembly and the APU engine. The oil flows back from the APU engine to the oil tank by gravity. The air in the oil goes out the turbine exhaust port.the oil tank has a filler port with a filier cap and dipstick. The oil can be added to the oil tank through the filier port. Also, the oil tank has a sight glass to do a check on the oil level Magnetic Drain Plug The magnetic drain plug is installed at the bottom of the oil tank. The magnetic drain plug has a magnetic element and a plug. When the oil tank is serviced, the magnetic element is removed to make sure no metal particles are in the oil. If the oil has metal particles, an investigation of damage to the APU engine is necessary. The magnetic element can be removed without the plug. When the plug and the magnetic element are removed together, the oil will drain from the oil tank. Oil Level Sensor The oil level sensor transmits a signal through the FADEC to show the APU oil quantity. The FADEC sends the signal to the MAINT Iight on the forward overhead panel and to the lube service panel. The oil level sensor has a tube, float and microswitch. The microswitch has two circuits that are operated by the fioat. The oil level sensor is installed on the bottom of the APU oil tank. FRA US/E gz Page: 18

23 OIL FWD FILLER PORT FOR THE OIL TANK OIL FILLER CAP MAGNETIC DRAIN PLUG FRA US/E gz CHECK VALVE OIL LEVEL SIGHT GLASS OIL LEVEL SENSOR OIL TANK PRESSURE FILL LINE Figure 9 GEARBOX (WITH INTEGRATED OILTANK) FWD Lubrication System Components DIPSTICK Page: 19

24 OIL COMPONENT DESCRIPTION Oil Cooler The oii cooler is installed on the APU below the APU electrical generator. The oii cooler is a rectangular unit made of aiuminum tubes. The oii cooler receives the oil from the oii pump. In the oil cooler the oil moves through the tubes where it is cooled by air from the cooling tan assembly. The oil tiows from the oil cooler to the gearbox assembly and the gears and bearings ot the APU engine. The oil cooler has a bypass valve that opens if the oil cooler is clogged. The bypass valve opens when the differentia! pressure across the oii cooler is 25 to 35 psig. The bypass valve is tu!iy open when the differential pressure is 45 psig Oil Pressure Relief Valve The pressure relief valve is installed in the lower part of the gearbox housing. The pressure relief valve keeps the oil pump pressure below 40 to 45 psig. If the pressure relief valve opens, the oil wili flow back to the oil tank. OiI Pressure Switch The oil pressure switch is installed on the gearbox assembly or on the oil cooler The oil pressure switch stops the APU when the APU oil pressure decreases to 20+/-2 psig. The signal from the oil pressure switch is monitored by the FA- DEC and the airplane electronics in the control cabin. Oil Pump and Filter Assembly The oil pump and filter assembly is installed on the gearbox assembly. The oil pump and filter assembly has the oil pump, oil filter element, filter bypass valve, differential pressure indicator, oil temperature switch and de-prime valve. A shaft that connects to the gearbox assembly drives the oil pump and filter assembly. The oil pump gets the oil from the oil tank. The oil pump moves the oil under pressure through the oil cooler to the gears and bearings of the APU. The oil filter assembly has an oil filter element. The oil filter element keeps ali unwanted material in the oil out of the oil pump. The oil filter element is a 2O micron fiiter that can not be cleaned. The oil filter element must be replaced. The oil filter element is installed on the oil pump and filter assembly. The filter bypass valve opens at psig when the oil filter element is clogged this permits unfiltered oil to enter the oil pump. A filter clogging indicator (red ) extends when the differential pressure across the oil filter element is 30 to 35 psig. High Oil Temperature Switch The oil temperature switch is found on the front of the oil pump and filter assembly. The oil temperature switch automatically stops the APU when the APU oil temperature is greater than 135 +/- 5 C The signal from the oil temperature switch is monitored by the FADEC and the airplane electronics in the control cabin. De-Prime Valve The de-prime valve is energized open when the APU is started. When the APU accelerates to 55% service speed, the de-prime valve is de-energized to the closed position. This will permit the oil pump to produce oil pressure. When the APU is stopped the de-prime valve is energized to the open position to stop the supply of oil to the oil pump. The oil that stays in the APU wiil drain to the oil tank. After 5 minutes APU stop the de-prime valve is de-energized to the close position.the de-prime valve is installed on the oil pump and filter assembly. The de-prime valve operates with a solenoid. FRA US/E gz Page: 20

25 OIL COOLING AIR FAN GENERATOR FLAME ARRESTOR GEARBOX OIL VENT TO APU EXHAUST OIL COOLER FWD OIL PRESSURE SWITCH FWD DE-PRIME VALVE OIL PUMP AND FILTER ASSEMBLY OIL FILTER BYPASS VALVE OIL FILTER CLOGGING IND. (RED) HIGH OIL TEMP. SWITCH FRA US/E gz GEARBOX OIL FILTER Figure 10 Lubrication System Components OIL PRESSURE RELIEF VALVE CARBON SEAL DRAIN WHITNESS PORT DO NOT PLUG Page: 21

26 OIL OIL TANK SERVICING Servicing of the oil sump is accomplished by opening the APU access door. The oil level is checked by removing the filier cap and using the dipstick. If the oil level is below the FULL mark, add oil until the Ievel is at the FULL mark on the dipstick. To assist in observing the servicing during the addition of oil, a Iine of sight access door is used. The Ievel of oil can be observed through this access during servicing. A hole drilled through the fiiler tube prevents overfiliing of the sump by allowing excess oil to drain out of the fill tube and into the APU lower shroud REMOTE OIL SERVICING The external service panel provides a means of replenishing the oil supply for the APU oil tank. Power Power for the system is 28 volts dc from the battery bus,switched hot bat bus or APU G.C.U. Maintenance Practices The oil tank is replenished by connecting the oil supply to the pressure fill connection and pumping oil into the tank until the green light iliuminates. Required oil supply pressure is 35 psi. FRA US/E gz Page: 22

27 OIL FULL GREEN LIGHT STABILIZER COMPARTMENT ACCESS DOOR OIL TANK SOLENOID VALVE APU OIL QTY MODULE M 925 PRESSURE FILL LINE TO OIL TANK ADD APU OIL TANK AMBER LIGHT DOOR OPEN SWITCH OIL TYPE FWD BULKHEAD STABILIZER COMPARTMENT FILL WHEN AMBER PRESSURE FILL CONNECTION LIGHT IS ON FRA US/E gz LUBE SERVICE ACCESS DOOR Figure 11 Oil Tank Servicing LUBE SERVICE PANEL DOOR OPEN SWITCH ACTUATING MAGNET Page: 23

28 OIL OIL SYSTEM SCHEMATIC DESCRIPTION Operation When the access door to the re-oil system is opened, 28 volts dc is supplied to Module M925. If the oil quantity is more than 2.6 U.S. quarts in the tank, the FULL switch provides a ground for the green (FULL) light, relay R253 and oil tank solenoid valve remains de-energized. If the oil quantity is less than 1.6 U.S. quarts in the tank, the ADD switch provides a ground for the amber (ADD) light, relay R253 and oil tank solenoid valve are energized. Adding oil to the tank opens the ADD switch and when tank has 2.6 U.S. quarts the FULL switch operates de-energizing R253 and solenoid valve FRA US/E gz Page: 24

29 OIL OFF ON TO APU CONT MCDU LOW OIL QUANTITY BITE CODE LOQ START TO APU CONT APU PANEL MAINT B ADD < 5% RPM APU MASTER CONTR. SW. (P5) CLOSE FADEC AFT CARGO CPTM OPEN FULL G APU CONTROL UNIT ( E3-3 ) M280 DOOR OPEN SWITCH ADD A WHEN OIL LEVEL ADD SIGNAL TO FADEC DURING APU START AND SHUTDOWN. 28V DC SWITCHED HOT BAT BUS APU CONT FULL CIRCUIT BREAKER PANEL ( P6-5 ) 28V DC SWITCHED HOT BAT BUS APU GENERATOR CONTROL UNIT ( P6 ) FRA US/E gz Figure 12 OIL TANK SOLENOID VALVE OIL QTY RELAY R 253 M 925 APU OIL QTY MODULE Oil Servicing System Schematic ADD OIL LEVEL SENSOR APU OIL TANK Page: 25

30 ENGINE FUEL AND CONTROL APU FUEL SYSTEM Purpose The APU fuel system receives fuel from the airplane wing tanks through a shrouded line. The system then pressurizes, filters, and meters fuel for combustion. The primary components are the fuel control and pump assembly. low and high pressure filters, a start fuel purge solenoid valve, start and main fuel manifolds, and nozzles. The APU is a constant speed engine. Speed control is accomplished automatically by the FADEC through torquemotor inputs to the fuel control and pump assembly, resulting in fuel flow regulation. Fuel Control and Pump Assembly This assembly accomplishes all pressurizing, filtering, and metering for the APU. Electrical connections include the servo valve, the start fuel solenoid valve, and the main fuel solenoid valve. SYSTEM OPERATION Starting Placing the APU switch to START and ON, opens the APU fuel shutoff valve and the inlet door begins to open. When the inlet door is full open,the FADEC activates the starter and energizes the start fuel solenoid valve to open. The start fuel solenoid valve is located on the fuel control and pump assembly. The APU fuel control and pump assembly then receives fuel from the airplane tanks through the APU fuel line. A low pressure centrifugal pump pressurizes the fuel and delivers it to the high pressure gear pump through the external low pressure fuel fitter. Unmetered fuel flows through the start fuel solenoid valve, through the start manifold and through the 4 start nozzles into the combustor. The FADEC energizes the ignition exciter one second after the starter is energized. The FADEC energizes the main fuel solenoid valve to open when the APU reaches 5% RPM with an increase of 28 C EGT. This permits metered fuel to flow through the in-line filter, through the check valve to the 14 main fuel nozzles. When the APU reaches 55% RPM, the FADEC deenergizes the starter and ignition exciter. At 70% RPM the FADEC de-energizes the start fuel solenoid valve to the close position and energizes the start purge solenoid valve to the open position for 60 seconds. This removes fuel from the start fuel manifold and nozzles. The FADEC monitors APU the EGT during starting. The FADEC sends electrical control signals to the servo valve to meter the fuel flow Running (APU RPM Above 98 Percent) The FADEC receives APU RPM, EGT, inlet temperature and inlet pressure signals from APU sensors. The FADEC sends electrical control signals to the servo valve to meter fuel flow to the main fuel nozzles. This keeps the APU at a constant speed with the APU supplying electrical and/or pneumatic loads or with the APU unloaded. Shutdown Placing the APU switch to off position : The fuel shutoff valve closed. The air inlet door closed. The main fuel solenoid valve de-energized to the close position. The fuel servo valve deenergized. The start purge valve energized to the open position for 30 seconds. Remaining fuel in the APU combustor drains through a drain valve into the lower shroud drain Iine. The de-prime valve energized to the open position. The anti-surge bleed valve energized to the closed position. The hour meter and start counter off. FRA US/E gz Page: 26

31 ENGINE FUEL AND CONTROL FROM APU AC FUEL BOOST PUMP FUEL TANK 1 LEGEND M M FADEC APU FUEL DC BOOST PUMP LOW FUEL PRESSURE HIGH FUEL PRESSURE ÈÈÈÈÈ REGULATED FUEL PRESSURE ÇÇÇÇÇ APU BLEED AIR ÂÂÂÂÂ OIL TANK VENT AIR FRA US/E gz OPEN: RPM >70% FOR 60 SEC. AND APU SHUT DOWN FOR 30 SEC. OPEN: AFTER STARTER CUT IN OR (>2% RPM) CLOSED: RPM >70% FADEC MODULATED POSITION OPEN: RPM 5% AND EGT RISE >28 C APU FUEL SHUTOFF VALVE M FUEL SHROUD DRAIN FUEL HEATER CHECK VALVE FUEL HEATER FLOW CONTROL VALVE <18 o C APU BLEED AIR CHECK VALVE Ç Â ÇÇ ÇÇÇ Ç Ç APU BLEED AIR BYPASS VALVE 10 PSID MAIN FUEL SOLENOID VALVE FILTER S LP-FUEL PUMP 40 PSI Figure 13 Í Í Í Í Í Í Í ÍÍ DIFF. PRESS VALVE 200 PSID... FUEL SERVO VALVE FUEL FILTER CLOGGING INDICATOR 6 PSID START FUEL SOLENOID VALVE RELIEF VALVE 640 PSID S SEAL DRAIN START PURGE VALVE HP FUEL PUMP 600 PSI CONTROL / PUMP ASSEMBLY Fuel System Schematic S SPEED SENSOR GEARBOX (2) T AMB P AMB FILTER MAIN CHECK VALVE TO DRAIN CHECK VALVE MAIN FUEL MANIFOLD START FUEL MANIFOLD TO FADEC NOZZLES DRAIN CHECK VALVE APU BLEED AIR DUCT ÍÇ Í Í Í Í ÂÂ Í ÂÂ ÂÂ COMBUSTER FROM START PURGE VALVE TO DRAIN MAST OIL TANK VENT LINE EXHAUST FLAME ARRESTOR IGNITOR (2) EXH. DRAIN EGT PROBE (2) Page: 27

32 ENGINE FUEL AND CONTROL APU FUEL SHUTOFF VALVE The valve allows fuel supply from the tank to the APU engine. Physical Description The valve consists of an actuator assembly and valve body assembly. The actuator is motor operated with a manual override. Power The valve motor utilizes 28 volt dc power. Control The valve operation is controlled by the APU switch on P5 panel and by protection circuits in module M280, APU control unit. The valve is installed on the rear spar of No.1 fuel tank in the Ieft main wheel weli. Operation. The valve is opened by placing the APU switch to the ON position. The valve can be closed by the switch placed to the OFF position or automaticaliy by fire detection or operation of fire handle. The valve can be operated manually without electrical power by the override handle. Maintenance Practices The valve actuator assembly can be removed separately from the valve body. The removal of the valve body requires No. 1 tank entry. APU FUEL DC BOOST PUMP The pump supplies pressurized fuel during starting of the APU. Physical Description The pump consists of a motor driven vanes, bypass valve, inlet and outlet ports. It is held in position by four boats through fianges on pump body. Power The pump utilizes 28 volt dc power Control The pump operation is controlled by the APU switch and main tank No. 1 boost pump switches on P5 panel. The pump is mounted on the wing bottom skin aft of the rear spar. Operation The pump operates only during APU start if: the APU Master Switch is in ON and Boost Pump relays from tank #1 are OFF and APU RPM is below 98%. When the APU reaches 98% RPM during the start cycle, the APU pump is automatically de-energized. FRA US/E gz Page: 28

33 ENGINE FUEL AND CONTROL LEFT REAR WING SPAR APU DC BOOST PUMP FUEL OUTLET MANUAL OVERRIDE LEVER FRA US/E gz APU FUEL SHUTOFF VALVE FWD INBD FUEL INLET LEFT LOWER INBOARD TRAILING EDGE PANEL ATA Figure 14 APU Fuel Shutoff Valve and DC Fuel Boost Pump INBD FWD Page: 29

34 ENGINE FUEL AND CONTROL START NC ON APU START CIRCUIT OFF APU MASTER CONTR. SW. (P5) NORM 28V DC NORMAL SHUTDOWN APU AIR INLET DOOR DISCH R FIRE APU FIRE HANDLE NORM M CLOSE OPEN NC NC M CLOSE OPEN FULL OPEN DOOR NOT FULLY OPEN FIRE APU REMOTE CONTROL PANEL FIRE DETECTION MODULE M 279 FIRE RELAY 28V DC APU FUEL SHUTOFF VALVE APU AIR INLET DOOR ACTUATOR DOOR OPEN SWITCH 28V DC SWITCHED HOT BAT BUS APU GENERATOR CONTROL UNIT ( P6 ) 28V DC SWITCHED HOT BAT BUS APU CONT CIRCUIT BREAKER PANEL ( P6-5 ) FRA TS82 hs APU MONITOR APU SHUTDOWN SIGNAL POWER SUPPLY APU CONTROL UNIT M 280 Figure 15 APU Fuel Shutoff Valve Control FADEC FADEC M 3056 AFT CARGO CPTM Page: 30

35 ENGINE FUEL AND CONTROL START NC BAT BUS APU FUEL BOOST PUMP M APU ON OFF MASTER CONTROL SWITCH CIRCUIT BREAKER PANEL ( P6 ) NC R 155 APU FUEL BOOST PUMP RELAY APU FUEL BOOST PUMP APU SPEED > 98% RPM NC R 191 BOOST PUMP SHUT-OFF RELAY R 18 TANK 1 AFT FUEL BOOST PUMP RELAY NC R 19 TANK 1 FWD FUEL BOOST PUMP RELAY P 6 LOAD CONTROL CENTER - R FADEC M 3056 AFT CARGO CPTM FRA TS82 hs APU MONITOR 28V DC Figure 16 POWER SUPPLY APU CONTROL UNIT M280 ( E3-3 ) DC Fuel Boost Pump Control APU GCU( P6 ) APU CONT 28V DC SWITCHED HOT BAT BUS 28V DC SWITCHED HOT BAT BUS CIRCUIT BREAKER PANEL ( P6 ) Page: 31

36 ENGINE FUEL AND CONTROL FUEL HEATER The fuel heater is used to prevent ice from blocking the fuel filter. The heater is a tubular fuel / air heat exchanger. The control valve has a bimetallic element for sensing the fuel temperature and allowing bleed air to pass through the heater. The fuel heater and control valve with a temperature sensor are attached to the inside surface of the upper shroud FIow Control Valve When the fuel temperature passing through the valve decreases to 3 C (37 F), the valve modulates to full open. This allows hot air from the APU bleed duct to pass through the heater and dumps into the shroud. When fuel temperature increases to 18 C (64 F), the valve closes. FueI Heater Check Valve A check valve is installed in the fuel Iine upstream of the heater to retain fuel in the pump. This ensures a positive prime for starting. FIow Control Check Valve A check valve is instalied in the air line to prevent fuel entering the bleed air duct. FRA US/E gz Page: 32

37 ENGINE FUEL AND CONTROL FUEL HEATER CHECK VALVE UPPER SHROUD FUEL HEATER OVERBOARD DUMP LINE FOR THE BLEED AIR FLOW CONTROL VALVE INLET LINE FOR THE BLEED AIR FRA US/E gz FWD Figure 17 FUEL INLET LINE FUEL HOSE Fuel Heater and Flow Control Valve APU BLEED AIR DUCT PRESSURE LINE TO PNEUMATIC ACTUATOR FLOW CONTROL CHECK VALVE Page: 33

38 ENGINE FUEL AND CONTROL ELECTRONIC FUEL CONTROL AND PUMP ASSEMBLY The fuel control and pump assembly supplies high pressure fuel to the start fuel manifold and high pressure, metered fuel to the main fuel manifold. It is mounted to the front face of the accessory gearbox with a quick attach/detach clamp. The fuel control and pump assembly consists of the following components: Centrifugal Pump Gear Pump High Pressure Relief Valve Start Fuel Solenoid Valve Main Fuel Solenoid Valve Differential Pressure Valve Fuel Servo Valve Centrifugal Pump rise up the Fuel Pressure to 40 PSIG. Protects the Gear Pump against cavitation. Gear Pump rise up the fuel pressure (100% RPM) to 600 PSID with a fuel flow of max 646 kg/h Main Fuel Solenoid Valve The main fuel solenoid valve permits metered fuel to flow through the main fuel manifold to the main fuel nozzles. It is energized open during APU start, if RPM > 5% and EGT rise >28 C. It closes during APU shutdown. Differential Pressure Valve The differetial pressure valve holds a constant differential pressure of 200 PSID across the fuel servo valve. This differential pressure creates a linear relationship between fuel flow and torquemotor current. Fuel Servo Valve The servo valve controls the fuel flow output from the fuel control and pump assembly. The servo valve is a torquemotor operated flapper type valve. The valve s position is electrically controlled by the FADEC and has a regulating range from 7 to 250 kg/h. The servo valve current is a function of APU speed, inlet temperature and pressure; and is EGT limited. High Pressure Relief Valve The high pressure relief valve protects the fuel system against overpressurization. It has a crack point pressure of 640 psid. Start Fuel Solenoid Valve The start fuel solenoid gets a signal from the FADEC to permits unmetered fuel flow through the start fuel nozzles. opens, after start circuit aktivation. Software Conf.15 or opens, if RPM > 2% Software Conf.16 ( FF ca 10 kg/h) closes, if RPM > 70%. FRA US/E gz Page: 34

39 ENGINE FUEL AND CONTROL GEARBOX FWD START FUEL SOLENOID VALVE FUEL PUMP FUEL SERVO VALVE MAIN FUEL SOLENOID VALVE FUEL CONTROL AND PUMP ASSEMBLY FRA US/E gz FUEL DRAIN TUBE DIFFERENTIAL PRESSURE VALVE Figure 18 FWD Fuel Control and Pump Assembly Page: 35

40 ENGINE FUEL AND CONTROL START PURGE VALVE The start fuel purge solenoid va!ve allows APU compressor discharge air to remove remaining fuel in the start fuel manifold and nozzles. This prevents coking of the start fuel nozzles. The start fuel purge solenoid valve is a normally closed shutoff valve. The FA- DEC energizes the solenoid for 60 seconds to open when the APU reaches 70% RPM. This permits compressor discharge air to purge the start manifold and nozzles of remaining fuel. When the APU Master switch is placed to OFF; the start fuel purge solenoid valve is energized to the open position for 30 seconds and then deenergized to the closed position, The start fuel purge solenoid valve is Iocated on the left side of the APU just aft of the ignition exciter. it is located in the high pressure start fuel Iine between the fuel control and pump assembly and the start fuel nozzles. Start Fuel Manifold The start fuel manifold and four start nozzles along with the main fuel manifold and fourteen fuel nozzles deliver fuel to the combustion chamber for APU operation. Start Fuel Nozzles ( 4 ) four start nozzles deliver fuel to the combustion chamber for APU operation Filter Clogging Indicator Filter Clogging Indicator ( Red ), is shown at 6 PSID. Indicates a clogged fuel filter. is resettable. Fuel Filter Fitting protects the 14 Main Fuel Nozzles against contamination. Main Check Valve closes when APU is Shutdown. Drain Check Valve opens after APU Shutdown, drains the unburned fuel of the Combustion Chamber, connects the Drain Lines to the Drain Mast. closes when the Combustion Discharge Presssure ( CDP ) increases (15% APU RPM ) drains fuel from Start Fuel Nozzles and Start Fuel Manifold during - APU Start > 70% APU RPM and - during every APU Shutdown when the Start Purge Valve opens, drains fuel to the Drain Mast (13 ccm Drain Fuel ). Main Fuel Manifold The main fuel manifold attaches to the main fuel nozzles ( 14 ). The main fuel nozzles bolt to the combustor housing. Air in the combustor atomizes the fuel through a slot in the fuel nozzles. Main Fuel Nozzles ( 14 ) Fourteen fuel nozzles deliver fuel to the combustion chamber for APU operation.the main fuel nozzles supply fuel to the combustor at 550 pph.air in the combustor atomizes the fuel through a slot in the fuel nozzles. besteht aus: Fuel Filter protects the fuel Gear Stage against contamination. Filter Bypass Filter Bypass, opens at 10 PSID. FRA US/E gz Page: 36

41 ENGINE FUEL AND CONTROL START FUEL MANIFOLD IGNITOR MAIN FUEL MAIN FUEL MANIFOLD NOZZLE ( 14 ) FWD COMBUSTION CHAMBER START PURGE VALVE START FUEL NOZZLE ( 4 ) FILTER CLOGGING INDICATOR START FUEL MANIFOLD DRAIN LINE TO DRAIN CHECK VALVE FUEL FILTER ASSEMBLY FUEL FILTER FUEL FILTER FITTING FRA US/E gz MAIN CHECK VALVE MAIN FUEL MANIFOLD Figure 19 Fuel System Components COMBUSTION CHAMBER DRAIN LINE DRAIN CHECK VALVE Page: 37

42 ENGINE FUEL AND CONTROL FUEL SYSTEM OPERATION Starting The APU start sequence is controlled by the FADEC. After the start relay is energized (Software version 15) or After 3% RPM (Software version 16), the fuel solenoid energizes and opens. (At 2% RPM ignition is activated) Unregulated fuel from the high pressure fuel pump is supplied to the start fuel manifold. It enters the combustion chamber via 4 start nozzles. After 1 second ignition is activated (Software version 15). At a speed of 5% RPM and a minor of 28 C EGT rise, the main fuel solenoid valve opens. The fuel servo valve starts controlling the fuel flow. The magnitude of the regulating fuel flow depends upon RPM, EGT, T-amb and P-amb. Control is provided by the temperature control circuit within the FADEC. At this point the fuel flow is approximately 25 kg/h and will continuosly increase. Regulated high-pressure fuel goes into the main fuel manifold, from where it leaves through 14 main fuel nozzles for combustion. At 55% RPM ignition is deenergized. At 70% RPM the start fuel solenoid valve closes and the start purge valve energized open for 60 sec. CDP air enters the 4 start fuel nozzles in order to blow out the remaining fuel from the start fuel manifold. At 80% RPM the temperature control circuit is turned off and the speed control circuit will now control the fuel flow. Running Speed > 98% 2 sec after 98% RPM load can be applied. The fuel servo valve, controlled by the FADEC, coverns the fuel flow to keep the APU-speed at 100% at all normal loads. The max. load factor is limited by the EGT-set point. The EGT-set point is variable and is computed by the FADEC. The set point depends upon T-amb and P-amb (see EGT-Chart). The max. EGT is slightly higher than the EGT-set point. An exceedance of max. EGT will cause an APU Auto Shut Down Shutdown When the APU Master Control Switch is put to OFF following fuel valves will close: Main Fuel Solenoid Valve Fuel Servo Valve and APU Fuel Shutoff Valve Start Purge Valve opens for 30 sec. and closes again. FRA US/E gz Page: 38

43 ENGINE FUEL AND CONTROL AMBIENT TEMPERATURE OF ( C ) FRA US/E gz MAXIMUM EGT C EGT Limit - APU Speed more than 98% Figure 20 APU-MAX. EGT CHART Page: 39

44 POWER PLANT DRY MOTOR THE APU General: You dry motor the APU to operate the APU without fuel to the start fuel nozzles. Procedure Set the switch and the circuit breaker: Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag. Open this circuit breaker and attach a DO-NOT-CLOSE tag: APU Control Unit, E3-3 Electrical Shelf, Put the container below the start fuel manifold. Disconnect the fuel line for the start fuel manifold from the start purge valve. Connect the fuel hose to the start purge valve. Put the end of the fuel hose into the container. Set these circuit breakers and these switches: Remove the DO-NOT-CLOSE tag and close this circuit breaker: APU Control Unit, E3-3 Electrical Shelf, Remove the DO-NOT-OPERATE tag from the APU master switch on the P5 forward overhead panel. Set the BAT switch on the P5 forward overhead panel to the ON position. Make sure this circuit breaker is closed: DC BOOST PUMP. on the P6-5 Load Control Center Assembly. Set the APU master switch on the P5 forward overhead panel to the START position and release it to the ON position. Permit the APU engine to motor until the APU has an automatic shutdown. Make sure the FAULT light comes on. NOTE: The FAULT light is on the P5 forward overhead panel. Make sure the FADEC has a LITE BITE code shown. Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag. B /430/ FRA TS82 hs Page: 40

45 POWER PLANT START PURGE VALVE B /430/530 FUEL LINE FOR START MANIFOLD FUEL OFF ON P 5 FWD OVERHEAD PANEL APU MASTER CONTROL SWITCH CIRCUIT BREAKER APU CONTROL UNIT E3-3 IGNITION EXCITER FWD ÅÅÅÅ ÅÅ Å ÅÅÅ FUEL HOSE ÅÅ CONTAINER APU CONTROL UNIT FAULT DISPLAY SWITCH FAULT DISPLAY CIRCUIT BREAKER FRA TS82 hs ON BAT OFF P 5 FWD OVERHEADPANEL TR NO.3 3 BAT BUS APU FUEL BOOST PUMP 50 5 CIRCUIT BREAKER Figure 21 P6-5 P 5 FWD OVERHEADPANEL APU MASTER CONTROL SWITCH APU Dry Motoring START ON LITE FADEC Page: 41

46 POWER PLANT WET MOTOR THE APU General: You wet motor the APU to operate the APU without ignition. Procedure Set the switch and the circuit breaker: Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag. Open this circuit breaker and attach a DO-NOT-CLOSE tag: APU Control Unit, E3-3 Electrical Shelf. Put the container below the combustor drain. WARNING: DO NOT TOUCH THE IGNITION COMPONENTS UNTIL YOU DO THESE STEPS. THESE STEPS WILL RELEASE THE HIGH VOLTAGE FROM THE IGNITION EXCITER. IF YOU DO NOT OBEY THIS PROCE- DURE, INJURY TO PERSONS CAN OCCUR. Do these steps to release the high voltage from the ignition exiter: Make sure 5 minutes have gone by since the last APU start. Disconnect the igniter cables from the igniter plugs. Ground the igniter cables to the APU. Disconnect the electrical connector from the ignition exciter. Set these circuit breakers and these switches: Remove the DO-NOT-CLOSE tag and close this circuit breaker: APU Control Unit, E3-3 Electrical Shelf. Remove the DO-NOT-OPERATE tag from the APU master switch on the P5 forward overhead panel. Set the BAT switch on the P5 forward overhead panel to the ON position. Make sure this circuit breaker is closed: DC BOOST PUMP, P6-5 Load Control Center Assembly. Set the APU master switch on the P5 forward overhead panel to the START position and release it to the ON position. Permit the APU engine to motor until the APU has an automatic Shutdown. Make sure the FAULT light comes on. NOTE: The FAULT light is on the P5 forward overhead panel. B /430/ Make sure the FADEC has a LITE BITE code shown. Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag. FRA TS82 hs Page: 42