During a normal ground start, what is the primary purpose of the Display Processing Computers in the engine start-switch circuit?, They directly supply electrical power to the starter air valve solenoids and control pneumatic flow to the starter., They receive switch-position data, provide the start-switch hold function, pass start information to the Electronic Engine Controls and release the switch when commanded., They calculate starter cutout speed independently and mechanically release the engine start switch when N2 reaches the required value., The Starter Air Valve is being manually operated during maintenance. Why must pneumatic pressure still be supplied to the valve?, Pneumatic pressure prevents excessive differential loading on the actuator diaphragms while the manual override changes valve position., Pneumatic pressure is required only to provide a valid valve-position signal to the Electronic Engine Controls., Pneumatic pressure provides lubrication to the flexible manual-drive shaft while the valve is being rotated., At approximately 60 percent N2 during a normal start, what sequence occurs within the air turbine starter system?, The starter air valve remains open while the clutch disengages mechanically from centrifugal force, after which pneumatic pressure is removed., The starter air valve closes, the turbine and reduction gears decelerate, and the clutch disengages while the starter output shaft continues turning with the engine., The starter air valve modulates toward closed while the starter turbine continues driving the engine until idle speed is reached., During Bowed Rotor Start motoring, how does the Electronic Engine Control prevent N2 from accelerating above the required motoring speed?, It modulates the Starter Air Valve by intermittently removing electrical power from its solenoids., It cycles the Air Turbine Starter clutch between engaged and disengaged positions., It modulates the engine bleed isolation valve while keeping the Starter Air Valve fully open., A maintenance motoring procedure has already used two extended starter operations of less than 15 minutes each. What restriction applies to subsequent starter operations?, Each subsequent operation is limited to five minutes, with a minimum ten-minute wait between engine motoring cycles., Each subsequent operation remains limited to 15 minutes, but the cooling period increases to ten minutes., Only normal two-minute starter cycles may subsequently be used until the starter has cooled for one hour., Why does the Bowed Rotor Start system deliberately prevent both fuel and ignition while the engine is being motored?, It allows the N2 rotor temperature distribution to equalise before combustion, reducing rotor bow, rubbing, start-stall and high-vibration risk., It allows the fuel manifold to completely drain before the Electronic Overspeed system performs its pre-start test., It prevents the High Pressure Compressor from accelerating until the Low Pressure rotor has reached its normal idle speed., Which inputs are specifically used by the Electronic Engine Controls to calculate Bowed Rotor Start motoring dwell time?, Compressor discharge temperature and Turbine Center Frame core vibration., N1 speed and Exhaust Gas Temperature., Starter-air pressure and Accessory Gearbox oil temperature., After Bowed Rotor Start motoring is complete, the engine start lever is moved to IDLE. Why does light-off not necessarily occur immediately?, The Electronic Engine Controls first perform fuel manifold prefill and then test the Electronic Overspeed and Thrust Control Malfunction Accommodation system before permitting fuel and ignition., The Display Processing Computers delay ignition until the Starter Air Valve reaches its fully closed position., The Auxiliary Power Unit Electronic Control Unit must first return its inlet guide vanes to the minimum bleed-air position., An Electronic Engine Control automatically aborts a ground start because no light-off occurred. Why should the engine subsequently be dry-motored before another start attempt?, Dry motoring cools the starter turbine before another starter duty cycle begins., Dry motoring removes the flammable fuel-and-air mixture remaining in the engine without introducing additional fuel or ignition., Dry motoring restores the fuel manifold pressure required for the next Electronic Overspeed system test., Which abnormal start condition is specifically listed as one that the Electronic Engine Controls detect, but is not necessarily included among the conditions that automatically abort every ground start?, The crew must wait until the MOTORING indication disappears and the engine reaches maximum motoring speed before moving the start lever to IDLE., The engine must first reach 60 percent N2 so the starter clutch can disengage before fuel is introduced., The start lever must remain at CUTOFF until the Starter Air Valve begins its automatic closing sequence.

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