Engine Starting.docx

Engine Starting 2A-80-10: Engine Starting System General: The engine start system supplies the mechanical energy necessary to rotate the core compressor and achieve the operational speed necessary for engine start, dry cranking andwet cranking. Forairstarts, required airflow is available from ble...

Engine Starting 2A-80-10: Engine Starting System General: The engine start system supplies the mechanical energy necessary to rotate the core compressor and achieve the operational speed necessary for engine start, dry cranking andwet cranking. Forairstarts, required airflow is available from bleed air supplied bythe APU (assisted airstart) or by air flowingthrough the engine (windmilling start). Ignition requirements are automatic or are met by continuous ignition, which is selected by the flight crew. Start and cranking cydes are initiated from the cockpit control panel to allow the FullAuthority Digital Engine Control (FADEC) to select normal (automatic) ground and airstart, alternate (manual) ground and airstart and wet or dry cranking. Note The power levers on the center pedestal must be in the idle position duringengine starting. The enginewill accelerate to the power setting commanded bythe power levers atthe completion of the starting process. A (caution) CAS message will be displayed to alert the crew if a power lever is forward of the idle position during engine start. The engine starting system consists of the following: Starter Air Valve (SAV) Air Turbine Starter (ATS) Starter Air Duct The system uses High-Pressure (HP) air to tum the ATS which then turns the HP compressor through the accessory gearbox. The SAV is electrically controlled by the Engine Electronic Controller (EEC) and supplies air to the ATS. When the start sequence is initiated from the flight compartment, the EEC will signal the SAV to open. HP air is then supplied through the ducting to the ATS. During engine startingthe pressure regulating and shutoff valve is in the dosed position to prevent back flow of air into the engine. The starting system components are located on the outside of the Structural Bypass Dud (see Figure 1. Engine Starting System Simplified Block Diagram). Description of Subsystems, Units and Components: Starter Air Valve (SAV): The SAV controls the air supply to the ATS and consists of: A dual-coilsolenoid control valve A butterfly valve, rotating on a single axis Microswitches (to indicate valve "not dosed") A manual override feature with a mechanical position indicator SAV Operation -Solenoid De-energized: Upstream air passes to chambers A, B and C. Air pressure differential loading, plus the torsion spring closing load, forces the piston to close the butterfly valve. SAV Operation - Solenoid Energized: Air still passes to chambers A and B, but chamber C is now vented to the atmosphere, via the adjustable vent. Pressure in chamber B now overcomes the torsion spring load to force the piston to open the butterfly valve, allO'Ning air to the starter motor. Chamber C venting is controlled, by the adjustable vent, to prevent starter motor shock loading. It is set during manufadure and is not adjusted in service. The "Fail-safe" condition of Valve Closed is achieved if: The air supply to the valve fails or the diaphragm is split The electrical power to the solenoid fails .- - - - - - - - - - - - - - - - MANUAL OPERATION OF THE SAV PLACES A CREW MEMBER IN CLOSE PROXIMITY TO VERY HIGH TEMPERATURES AND EXTREMELY HIGH NOISE LEVELS. THE PROCEDURE REQUIRES A HEADSET OR OTHER MEANS OF COMMUNICATION WITH THE COCKPIT IN ORDER TO MONITOR ENGINE RPM DURING START FOR CUES IN TIMING THE OPERATION OF THE SAV. THE PROCEDURE SHOULD BE THOROUGHLY REVIEWED PRIOR TO PREFORMING THE OPERATION. SAV Control: Automatic: The SAV is controlled by the EEC (either channel) from pilot input. When normal (automatic) engine start is selected, the EEC will energize the SAV solenoid. This opens the valve and initiates engine rotation. Fuel flow and ignition are switched on automatically by the EEC. After a successful lightoff, the EEC will de-energize the solenoid at 43% N2, closing the SAV which disengages the starter motor. Note The valve can be operated manually to dispatch aircraft if it fails to operate under normal control command. Manual: When alternate (manual) start is selected, the EEC will energize the SAV solenoid. This opens the valve and initiates engine rotation. Fuel and ignition are switched on manually. After a successful lightoff, the EEC will de-energize the solenoid at 41% N2, closingthe SAV and thus disengaging the starter motor. V\lhen the SAV is open, the positional microswitches will generate a blue SVO icon alongside the N2 readout on the Engine Indicating and Crew Alerting System (EICAS) primary and start synoptic pages. If an electrical failure of the SAV solenoid prevents normal engine starting, a procedure is provided for manually opening the SAV to power the starter turbine in order to dispatch the aircraft. See 07-00-60: Manually Overriding Starter Air Valve for instrudions regarding the procedure. If a failure during an engine start prevents the SAV from closing at the normal starter cutout HP rpm, the flight crew must shut off the bleed air supply to the SAV to prevent damage to the starter air turbine. The abnormal condition is indicated by the continued display of the L SVO or R SVO (left or right start valve open) text icon on the Engine Start 116 window after the engine has reached idle rpm (see Airplane Flight Manual I Abnormal I Engine Starting System I Start Valve Failure to Close After Engine Start). Air Turbine Starter (ATS): The ATS is mounted on the engine accessory gearbox at the forward section of the engine. Pneumatic pressurized air from the SAV is routed to the starter through a dedicated duct. When the SAV opens to drive the starter, air is directed againstthe blades of the turbine, rotating the starter. Air from the starter is exhausted through an outlet on the bottom of the engine cowling. The starter turns an attached gear assembly that is connected to the drive shaft of the accessory gearbox, rotating the engine HP rotor. A sprag dutch is incorporated in the starter gearing in order to disengage the starter when engine rpm exceeds starter drive speed. At starter disengagement, the EEC closes the SAV and the starter turbine spins down through the frictional forces of the gear assembly. The unit has its own self-contained oil system, the oil pump being driven by the output drive shaft.It has an oilfiller andlevel indicator plug, as well as a combined Magnetic Chip Detector (MCD) and oil drain plug. Oil replenishment is through the filler port. V\lhen oilislevel with the filler port, the quantity is correct. ATS Operation: Note The EEC does notlimit the number or duration of starter operations. This is the responsibli ity of the flight crew. Air from the aircraft pneumatic system, via the SAV, passes through the nozzle guide vanes to drive the single stage turbine, then exhausts through the unit outer casing to under the cowl (Zone 1). The turbinedrives an annular gear via three shafts. The annular gear in tum drives the output drive shaft through a sprag-type clutch. At starter cut out speed the SAV is closed and the turbine loses speed, which disengages the sprag clutch.The turbine wheel runs down to zero rpm and the output drive continues to rotate with the gearbox. The turbine and output shaft rotate in opposite directions and the turbinewheel to output drive shaft gear ratio is 13:1. Starter Air Duct: The starter air duct has two parts, front and rear, which are connected together with a V-band coupling damp. It is installed along the lower right side of the engine. At the rear,the duct is attached to the SAV and at the front to the ATS. The mating flanges are also connected with the V-band coupling clamps. Air leakage is prevented at the joints by metal seals which are installed between the mating flanges. Operational Summary: Starting System Functions: The engine can be started on the ground or airborne either automatically or manually. Air starts are either starter assisted or windmill depending upon aircraft speed and altitude. The EEC also provides an auto relight and a quick relight function. The quick relight function is only available in flight. The system is configured so that either starter can accept airfrom any one of three different sources: a ground unit, the auxiliary power unit or through an interconnecting duct from the opposite engine. The FADEC system interfaces with command signals from aircraft systems to control the following engine starting and cranking operations: Normal Ground Start: Engine ground starting mode in which the engine MASTER START switch is used. Temperature limits and functions are monitored and controlled by the EEC. Fuel High Pressure Shutoff Valve (HPSOV) and ignition control are automatic once the aircrew have selected the FUEL CONTROL switch to RUN. Alternate Ground Start: Engine ground starting mode in which the technician controlsthe start sequence. The engine MASTER CRANK switch is used in this mode. The EEC, upon commands from the cockpit, controls the fuel HPSOV. Ignition is commanded via the CONT IGN switch. The EEC does not limit TGT in this mode. Normal Air Start: Engine air starting mode in which engine limits and functions are monitored and controlled by the EEC. The engine MASTER START switch is used andthe fuel HPSOV andignition are automatic once the pilot has selected the FUEL CONTROL switch to RUN. Based on computed airspeed, the EEC will determine if a starter-assisted or windmillstart should be performed. The EEC does not limit TGT in this mode. Alternate Air Start: Engine air starting modeinwhich the pilot controls the start sequence. The engine MASTER CRANK switch is used in this mode. The EEC, upon commands from the cockpit, controls the fuel HPSOV. Ignition is commanded via the CONT IGN switch. The EEC does not limit TGT in this mode. The EEC will inhibit starter operation if N2 is above 41%. Alternate Windmill Air Start: This mode is for use when the starter is unavailable. The MASTER START or MASTER CRANK switches are not used and the pilot controls the start sequence. Ignition is commanded ON via the CONT IGN switch and the fuel HPSOV is controlled via the FUEL CONTROL switch. The EEC does not limit TGT in this mode. Dry Crank: Engine operating mode in which the engine is motored over without fuel (FUEL CONTROL switches OFF) or ignition (UR CONT IGN switches OFF). Wet Crank: Engine operating mode in which the engine is motored over with FUEL CONTROL switches ON and ignition off (UR CONT IGN switches OFF). Auto Relight: A function within the EEC which detects a flameout of the engine and automatically initiates an engine relight by turning on both igniters and controlling fuel flow. This function is not pilot-selectable. Continuous Ignition: Engine operating mode in which ignition (both igniters) is continuously operating. This mode is selected by the pilot (LJR CONT IGN switches ON) and controlled by the EEC and is available on ground or in flight. This mode is not time-limited, but will reduce overall igniter life. Quick Relight: A function within the EEC which detects the transition of the FUEL CONTROL switch from RUN to OFF and back to RUN when the engine isat or above the idle speed. The EEC automatically initiates an engine relight by turning on both igniters. This function is not pilot-selectable but continually operates in flight. Controls and Indications: Controls: (See Figure 2. Engine Starting System Controls and Indications.) Engine starting is electrically controlled by switches mounted on the Cockpit Overhead Panel (COP) and on the center console. The starter may be engaged in flight within the starter-assist envelope (as referenced in the AFM). The switches permit selection of lefl or right engine and also of "start" or "crank" sequence. The engine start I cranking I relight procedures are initiated via the following control switches: Note If both the MASTER CRANK and MASTER START switches are selected on, a {advisory) CAS message will be displayed to prompt the flight crew to select one or the other of the switches. MASTER CRANK (Cockpit Overhead Panel): The MASTER CRANK switch is a pushbutton type switch. The default position is OFF. When depressed, it is latched and the ON legend is illuminated. This position selects the engine for alternate (manual) starts or wet/dry cranking MASTER START (Cockpit Overhead Panel): The MASTER START switch is also a pushbutton switch. The normal position is 'relaxed', where the switch is not latched in and the ON legend is not illuminated. When selected ON, both normal and automatic, starts can be initiated L ENGIR ENG START (Cockpit Overhead Panel):The ENG START (engine start) switches are guarded pushbuttons which do not latch when depressed. When the SAV is not closed, the ON legend is illuminated and the switch will extend when released. A blue SVO icon is displayed alongside the N2 indication during normal operation. This changes to anamber SVO icon if the SAV remains open above starter disengagement speed CONT IGN (Cockpit Overhead Panel): The CONT IGN (continuous ignition) switch is aguarded pushbutton switchwhichlatches in either position. When depressed, the ON legend is illuminated.In this position, the EEC willswitch on both igniters in order to perform an alternate start, or, for continuous ignition (for as long as the button is depressed). A green IGN icon is displayed just below the SVO icon (beside the fuel flow indication) LIR FUEL CONTROL (Center Console): The FUEL CONTROL switches have RUN and OFF positions.During a normal start, the RUN position gives the EEC authority to open the Pressure Raising and Shutoff Valve (PRSOV) in the Fuel Metering Unit (FMU) at the appropriate time. During an alternate start, the ON position directly commands the EEC to open the PRSOV. Moving the switch to the OFF position willclose the PRSOV Indications: The engine start sequence indications and I or operating characteristics are as follows: The L ENGIR ENG START switch illuminates ON when the start relay is energized. It initiates the starting sequence for the selected engine, illuminates the SVO icon shown next to the HP indicator and provides an indication to the Engines synoptic page A blue SVO icon illuminates when the SAV passes through 7° on its way open and extinguishes when the valve is 5° from dosed When the EEC commands the SAV to close and the start relay is de-energized, the L ENG IR ENG START switch ON indication extinguishes.The MASTER START switch, however, remains ON untildeselected by the flight crew A flashing amber SVO icon on the engine instruments indicates that the start valve was commanded closed by the EEC but is still in the open position The (caution) CAS message is displayed when the SAV remains closed after the EEC commands the valve to open. {This is an indication that the SAV requires maintenance.) An alternative is to operate in manual mode. In this mode, the pilot coordinates with the maintenance technician, who manually opens and doses the SAV During normal start, if the throttle lever is not inthe idle position, upon selection of the MASTER START or MASTER CRANK switch to ON, the EEC activates the (caution) CAS message (indicatinga discrepancy between the throttle lever position and the engine automatic starting position) If uncorrected, the EEC will continue with the start sequence after lightoff and will accelerate the to the thrust set by the throttle lever position. The ll;li@'Ui....:....1!.li!f l@ {caution) CAS message is canceled when the MASTER START switch is deselected, the engine achieves the speed set bythe throttlelever or the throttle is returned to the idle position A complete description of the Engine Start 1/6 window display is contained in Section 28-09-00. Circuit Breakers (CBs): The following CBs power the engine starting system: Circuit Breaker Name CB Panel Location Power Source UR START A POP D-6 L ESS DC Bus UR START B CPOP D-6 R ESS DC Bus d. Crew Alerting System (CAS) Messages: The following CAS messages are associated with the Engine Starting system: Area Monitored CAS Message EEC L-R Autostart Abo (caution) EEC L-R SAV Maintenanc (caution) EEC L-R Throttle Configuration (caution) EEC Assisted Airsta (advisory) EEC Start Switch Configuratio (advisory) Limitations: Flight Manual Limitations: Starter Duty Cycle: The starter duty cyde is three start cydes with a maximum of three minutes per start cyde. Delay 15seconds between start cydes. After three start cydes,delay use of the starter for at least 15 minutes. (2) Starter Re-engagement: The starter may be re-engaged at HP rpm speeds up to starter cutout of 42% HP rpm. (3) Airstart Envelope: See Figure 3. Airstart Envelope. 0 m s:: :5. i !i :i CA ID o ;i :i ca m "0:;': 1602A AIRCRAFT ENGINE A/C PNE\JMATlC SYSTEM AIR SUPPLY (ECS BLEED DUCl) ACCESSORY GEARBOX (AGB) FLIGHT DECK CONTROLS F\JEL SUPPLY HP (FUEL I SDI/ IN) FLIGHT !JECK INCICATIONS "llN DC BUS IGtfTION EXQTER UNIT No.1 i'"" GI :""" m :J cc- en Iaii :J cc i 3 e:rn "2. Ill (j) m Ul 0m ::0 0 "U m z Gl )> c :::!. 6 2 Ol (ol FAN 111'-PAS&DUCT lll:Y: SOI= SOLENOID CONTROL VALVE FMU FUEL MANAGEt.ENT UNIT HPSDV •HC3H PRESSURE StfJTOFFVAJ..VE HPT HGHPRESSURE TURBINE LPT •LOW PRESSURE TURBINE 0 cc ii1 3 --------------------- "' "' Figure 2. Engine Starting System Controls and Indications SEE DETAIL A MASTER CRANK / START SWITCHES Altemate action switches. Normal position is off. When MASTER CRANK switch is selected ON, altemate engine starting mode and wat I dry aank mode are enabled. When MASTER START switch isselected ON, nonnal start mode isenabled. After IH!lection of either awitc:h to ON: Respective ONlegend illuminates blue. If APU is running, APU load control valve opens. If right ECS pack is operating, ECS packis shut down. Whan selected OFF: ON legend exilnguishes. Associated mode is disabled. If right ECS pack was operating when either switch was selected ON, ECS pack operation resumes. L ENGIR ENG START SWITCHES Guarded momentary action switches. Nonnal positionis off. Vlilth selection of either ENG START switch to ON and MASTER CRANK switc:h ON, a crank sequence for selected engine is initiated. Vlilth selection of either ENG START switch to ON and MASTER START switch ON, a l!llart sequence for selected engine is initiated. In either above case, the following also occuns when either ENG START switch is elected ON: Respective ONlegend illuminates blue. Ifleft ECS pack is operating, ECS pack is shut down. Starter Air Velw (SAV) opens to supply air to starter. SVO icon is displayed on Engine Instrument• PllliJe on Display Unit. Crank sequences are terminated manually. Start sequences can be terminated: Automatically under normal condition• by the EEC at appf'QXimately 42% HP RPM. Automatically under abnormal conditions at any time by the EEC. Manually by selection of the ENG START switch to OFF. VVhan the crank or start sequence i•terminated: ON legend extingui•hes. SAV closes. SVOicon axtinguishes. Ifleft ECS pack was operating when either ENG START switc:h was selected ON, ECS pack operation resumes. DETAIL A TIL-002638A OEM Provided Data Engine Starting BASICISSUE 2014-10..02 2A-80.00: 10 of 12 Figure 3. Airstart Envelope START ENVELOPE Q 20 Q ...... >< 15 L&. w STARTER ASSIST c REGION :.:.:.:.>. 10 -..... 250 Kts CAS 340 Kts CAS ..J c( 5 -5--+-..,..--,...........,.--+- --....----...,.---,---+---.--,--...---+----,.---..,..- ..,..--t---.,----.---r--! 0 0.2 0.4 0.6 0.8 1 MACH NUMBER TIL-006885 OEM Provided Data Engine Starting BASIC ISSUE 2014-10-02 2A-BO-OO: 11 of 12