DASSAULT FALCON 7X SYSTEMS SUMMARY Auxiliary Power Unit

APU DETAILED DESCRIPTION The APU consists of: - An air intake, located in the middle of the unit which connects to a structural RH lateral air inlet, - A centrifugal compressor and its bleed air port, - A combustion chamber, - A single stage turbine, - A primary exhaust duct, - A secondary exhaust duct acoustically treated and thermally insulated, - An accessory section. The accessories include: - The APU fuel control unit, - The fuel pump, - The oil pump, - The starter generator. APU LAYOUT Falcon 7X [APU Summary] Page 9 APU SYSTEMS FUEL SYSTEM The airplane fuel system supplies fuel to the APU Fuel Control Unit (FCU) via BOOST Pump 2 (which feeds also the No 2 Engine) through a dedicated APU fuel line, and an APU Fuel ShutOff Valve (FSOV). The FSOV opening and closing is managed by the APU ECU. The APU fuel line is able to feed the engine n°2 (central) in the failure case when the engine n°2 line is cut. IGNITION SYSTEM The APU ignition / starting system is fully automatic in operation and is controlled by the Electronic Control Unit (ECU). This system consists of: - The interface to the Starter / Generator and the GCU, - An ignition unit, - Two igniter plugs, - Two igniter leads. The functions of the ignition and starting system are as follows: - Provide cranking power for APU starting, - Provide ignition for combustion initiation, - Disengage the APU starter motor at the appropriate APU speed. Upon reaching 95% of N1, a signal from the ECU terminates the ignition. Falcon 7X [APU Summary] Page 10 APU ELECTRONIC CONTROL UNIT (ECU) The ECU is located in the mechanic-servicing compartment. APU operation is monitored through N1 signal generated by a magnetic sensor mounted on the accessory gearbox and a temperature signal (T5) generated by the single thermocouple probe installed in the APU exhaust duct. The speed-governing loop continuously monitors N1 and modulates fuel flow-timed acceleration during starting of the engine or control during self-sustaining operation. The temperature loop is not active during APU starting or normal operation unless exhaust duct temperature exceeds the maximum operating value. DISTRIBUTION The hot bleed air necessary for air conditioning is tapped downstream from the compressor. Falcon 7X [APU Summary] Page 11 OPERATION The APU is started using the DC Starter / Generator powered from battery No 1 connected to the LH Battery Bus (battery 1). During the APU start operation, the LH Battery bus is not connected to the LH Essential bus, as power to the LH and RH Essential buses is maintained by the No 2 battery or by the GPU. The Starter / Generator is controlled by a Generator Control Unit (GCU), both during the APU start and power generation. When the APU ECU is powered (by the crew members through the overhead MASTER p), it performs its BITE and opens the APU Fuel Shutoff Valve. Then, when the crew members push the START pushbutton, the Starter / Generator is energized and begins rotating the APU. As the APU main rotor speed (N1) reaches approximately 5% (N1), the ECU commands the ignition unit Solid State Power Control (SSPC) closed and the APU fuel shutoff solenoid valve opened. The ignition unit provides the electrical energy to create a spark across the igniter plugs. As the APU reaches approximately 50% (N1), the starter circuit is de-energized by the ECU. Electrical energy to the ignition system is terminated at 95% (N1) APU speed. As the APU reaches 95% (N1) of governed speed for more than 4 seconds, the ECU sends a Ready To Load (RTL) signal to the airplane system and the S/G can be commanded open to be loaded and provide electrical power to the airplane. Then, a certain time after having reached 100% (N1) of governed speed, when the ECU estimates that the APU operates satisfactorily and is capable to be air bled, the ECU allows the Load Control Valve (LCV) to open in case the bleed request is sent by the ECS AMSAC, in order to provide bleed-air to the airplane pneumatic system. For a normal APU shutdown, the ECU simulates an APU overspeed. Falcon 7X [APU Summary] Page 12 CONTROLS Crew controls of APU are performed via: - The APU portion of the overhead panel, - The APU FIRE pushbutton annunciator (Fire Control Panel), - The SERVICING page accessible in the TEST synoptic page, to test the APU oil level. APU PORTION OF THE OVERHEAD PANEL APU SECTION OF THE OVERHEAD PANEL Falcon 7X [APU Summary] Page 13 TO ACTIVATE CONTROL FUNCTION TO DEACTIVATE SYNOPTIC Powers the APU (APU not running and not powered) Push to power before start-up N1 and T5 values are not displayed Deactivates the APU (APU only powered and not running) Push to deactivate Abnormal APU stop or faulty Built-In-Test: - Blinking at 1 Hz: a pilot action on the MASTER pushbutton is possible or requested, - Blinking at 5 Hz: pilot action forbidden. The system is evolving automatically No action N1 and T5 values are displayed in the ENG synoptic page and ENG-TRM window. Push to start Initiates APU starting sequence when the ON light only is on. Initiates APU shutdown when both ON and RUN lights are on (APU running). Push to stop Falcon 7X [APU Summary] Page 14 MASTER pushbutton: - Provide primary power to the ECU, - Powers the aircraft Fuel Shut off open, - Allow the ECU power up sequence ("ON" illuminated when ready). The ON green light associated to the MASTER pushbutton is lighted when the APU is electrically powered. The START STOP pushbutton command start stop sequence of APU operation. The RUN green light associated to START STOP pushbutton is lighted when the APU is running. TEST SYNOPTIC PAGE In the TEST synoptic page, APU OIL status can be obtained through SERVICING window. SERVICING PAGE The test must be performed once a day with the APU off and the RH MASTER being ON. The system indicates: - If APU oil level is valid: , - If APU oil level is too low: , - If the oil data is invalid: . NOTE An hour meter located in the servicing compartment, records APU operating time. It automatically begins to record as soon as the APU N1 reaches 97% N1. Falcon 7X [APU Summary] Page 15 INDICATIONS Cockpit indications related to APU are displayed on: - The ELEC synoptic page (for APU generator status and ammeter measurement), - The ENG-TRM window (for APU parameters) - The ENG synoptic page (for APU parameters) ELEC SYNOPTIC PAGE As the APU supplies electrical power to the airplane, APU electrical indications can be displayed in the ELEC synoptic. This page indicates APU generator status and the corresponding ammeter measurement. ELEC SYNOPTIC - APU RUNNING Falcon 7X [APU Summary] Page 16 APU GENERATOR SYMBOL The APU generator status can be: - On line (green outlined synoptic), or - Disconnected (gray outlined synoptic), or - Failed (amber outlined synoptic). The ammeter indicates normal operating values or abnormal values using the following rules. APU AMMETER INDICATIONS The digital readouts are only displayed when the airplane is on the ground with APU running. The range of the scale is amber above 400 A. Falcon 7X [APU Summary] Page 17 ENG-TRM WINDOW APU engine parameters are displayed at the bottom of the ENG-TRM window. ENG-TRM WINDOW ENG SYNOPTIC APU Engine parameters are also displayed at the top right hand corner of the ENG Synoptic. APU INDICATIONS IN ENGINE SYNOPTIC Falcon 7X [APU Summary] Page 18 N1 indications APU N1 95 % N1 between 0 to 102 %: normal APU start or operation. No crew members action required APU N1 103 % N1 between 102 % and 105.9 %: limited APU overspeed, APU can continue. Crew members to be careful APU N1 --- % APU speed unknown: crew members must check that the APU is auto shutdown T5 indications T5 600 °C T5 below 870°C in normal operation (985°C at start up): normal APU start or operation. No crew members action required T5 990 °C T5 above 870°C in normal operation (985°C at start up): APU auto-shutdown due to overheat. Crew members must check that the APU is stopping. T5 --- °C Exhaust Gas Temperature unknown: crew members must check that the APU is auto shutdown Falcon 7X [APU Summary] Page 19 SYSTEM MONITORING Following APU parameters are monitored: - Any APU fault, - APU Load Control Valve (LCV) fails to open when command. ACTIVE PROTECTIONS A protective automatic shutdown is initiated in case of: - Fire, - APU operating limit are exceeded, - Loss of Weight On Wheel signal, - Starter / Generator tripped off-line, - ECS overheat. Falcon 7X [APU Summary] Page 20 ACTIVE PROTECTIONS For a normal APU shutdown, the ECU simulates an APU overspeed. Therefore, the overspeed protection system included in the ECU is tested at each end of APU operation: it is the overspeed system test which avoids any dormant failure in this area. For a protective shutdown, the ECU bypasses the above overspeed system test and immediately commands the FCU shutoff valve and torque motor metering valve closed. For a real APU overspeed condition, both the ECU primary overspeed system and the software command the FCU shutoff valve and fuel metering valve closed. The events leading to the automatic protective shutdown of the APU are the followings: EVENT DEFINITION Over-speed APU speed exceeds 105.9 % High oil temperature APU oil temperature exceeds 162°C (325°F) for 10 seconds with the APU operating Loss of overspeed protection Loss of primary over-speed protection Reverse flow APU inlet temperature exceeds 132°C (270°F) for 5 seconds with the APU operating and the LCV open Loss of speed sensor signals Failure of speed sensor channel Under-speed APU was operating and speed drops below 80% for 5 seconds ECU failure Internal ECU failure that could result in loss of APU control Loss of EGT sensor EGT sensor channel failed No crank APU start SSPC activated and no APU speed detected APU fire/emergency A signal received by the ECU from the fire protection system No flame Fuel and ignition activated and no light-off detected Generator off-line The generator has failed and the APU shuts down after 5 minutes Falcon 7X [APU Summary] Page 21 EVENT DEFINITION No acceleration Light off detected but fails to accelerate to governed speed ECS Overheat The ECS system experiences an overheat shutdown and the APU shuts down after 5 minutes Loss of DC power Loss of Battery Bus and Battery Direct Bus Oil pressure switch failed Failure of low oil pressure channel Over-temperature APU EGT exceeds schedule limits : EGT limit = f(speed), duration maxi = f(EGT - EGT limit): for example at 100% speed, EGT limit = 760°C (1400°F) and duration maxi is 4 seconds at 760°C Low oil pressure Low oil pressure condition active (lower than 26 psi) for 15 seconds with the APU operating Loss of WOW signal The APU shuts down automatically when the WOW is lost. Falcon 7X [APU Summary] Page 22 APU OIL FILLER PORT APU OIL FILLER PORT Falcon 7X [APU Summary] Page 23