ATA 75 Air - Issue 6 January 2023_Compress.pdf

BOMBARDIER DHC 8-400 (PWC PW150) ATA 75 - AIR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 24 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM GENERAL DESCRIPTION The engine air system provides secondary air for engine co...

BOMBARDIER DHC 8-400 (PWC PW150) ATA 75 - AIR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 24 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM GENERAL DESCRIPTION The engine air system provides secondary air for engine cooling, cavity sealing and oil scavenging. It also gives compressor surge control, a pressure signal for bleed air control and NL decouple logic. The Air System provides compressed air for: • • • • • • • Cooling of hot engine components Bearing sealing Reference air pressure for the oil pressure regulating valve Scavenging of various bearing cavities P2.2 bleed valve operation P2.7 bleed valve operation P3 signal to the FADEC The air system is a critical system for the operation and performance of the engine. The function of the air system is done by these systems: • • • Cooling and distribution Compressor control Air indicating COOLING AND DISTRIBUTION SYSTEM The cooling and distribution system distributes air to the areas of the engine that require it and cools the hot section components. This air is also used for sealing and scavenging of the engine bearing oil cavities. COMPRESSOR CONTROL SYSTEM The compressor control system controls the performance of the compressor. The system uses two pneumatic valves controlled by the FADEC to prevent compressor surging. AIR INDICATION SYSTEM The air indication system senses compressor discharge pressure at the exit from the HP compressor (P3). This air pressure signal is then used by the: • • • Compressor stall logic Flameout logic NL decouple logic of the engine control system and the environmental control system BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - COMPRESSOR SURGE CONTROL SYSTEM BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION The secondary air distribution system supplies air for: • • • Cooling of the hot section components Bearing oil cavity sealing Scavenging AIR COMPRESSOR CONTROL The Air Compressor Control system controls the performance of the compressor to provide adequate stall margin under all operating conditions. GENERAL DESCRIPTION The function of the Air Compressor Control system is done by the: • • • • • • • • FADEC P2.2 Handling Bleed Off Valve P2.7 Handling Bleed Off Valve P2.7/P3 Check Valve P3 Air Separator P3 Air Separator to P2.2 Bleed Valve Air Tube P3 Air Separator to P2.7 Bleed Valve Air Tube Gas Generator Case to P3 Separator Air Tube SYSTEM OPERATION The Air compressor control System has two pneumatic valves for compressor control. They are located on the left and right sides of the engine. The valves are actuated by P3 air. An electrical signal from the FADEC controls P3 air. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - COMPRESSOR CONTROL SCHEMATIC BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION P2.2 HANDLING BLEED OFF VALVE The P2.2 handling bleed off valve prevents compressor stall and surge. The P2.2 handling bleed off valve is a normally open, dual coil torque motor driven, modulating in-line valve. It incorporates: • • • • An inlet An outlet Flange mounted servo port A Linear Variable Differential Transducer (LVDT) connected to a valve poppet An electrical connector is hard mounted to the torque motor. The P2.2 valve is located on the left side of the low pressure compressor case. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.2 HANDLING BLEED OFF VALVE LOCATOR BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P2.2 HANDLING BLEED OFF VALVE CONTINUED During engine start the valve is positioned to maximum bleed. During normal engine operation, the valve is modulated toward the closing position according to a FADEC schedule. The valve is positioned by a command signal from the FADEC to the valve’s torque motor. This signal moves the flapper rod, which changes the control pressure to the valve, upsetting the force balance and moving the valve. When the FADEC receives the LVDT position feedback signal, it commands the torque motor back to the null flapper rod position. This balances the forces on the valve and it remains stationary in its new position until the next FADEC command is received. During engine shutdown, the valve is commanded back to the full open position. The P2.2 valve provides redundancy in the event of a failure. The torque motor and LVDT each have 2 coils connected to 2 separately wired channels. In the event of a power loss to the torque motor, its null bias will cause the valve to open to its full bleed position. The valve is also designed to fully open if there is a loss of servo supply pressure. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.2 HANDLING BLEED OFF VALVE DETAIL BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P2.2 HANDLING BLEED OFF VALVE CONTINUED The P2.2 HBOV is fully modulating. It is controlled by the FADEC to provide surge margin during steady state operation. The amount of valve opening is biased closed by 50% whenever the Environmental Control System (ECS) is demanding P2.2 bleed for pre-cooling P3. This is done by transmitting a discrete from the ECS ECU to the ECIU and then to the FADEC on the ARINC 429 data bus. For a transient surge the amount of opening is biased open by 50% for the duration of the surge. For a steady state surge the amount of opening is biased open by 14%. The FADEC will retain this bias until a FADEC Fault Clear is done. If further surging is detected the FADEC will bias the HBOV open by an additional 14% to a maximum of 70%. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.2 HANDLING BLEED OFF VALVE STEADY STATE SCHEDULE BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P2.7 HANDLING BLEED OFF VALVE The P2.7 handling bleed off valve prevents compressor stall and surge. The P2.7 handling bleed off valve is a normally open, dual coil torque motor driven, on-off in-line valve. It has: • • • An inlet An outlet A flange mounted servo port An electrical connector is hard mounted to the torque motor. The P2.7 valve is located on the right side of the intercompressor case. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.7 HANDLING BLEED OFF VALVE LOCATOR BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P2.7 HANDLING BLEED OFF VALVE CONTINUED During engine operation the valve is positioned open or closed by a command signal from the FADEC. The signal is fed to either coil of the torque motor which then closes the servo supply pressure P3 and increases the vent area causing the control pressure to drop. The compressor bleed pressure P2.7 pushes on the underside of the valve poppet and opens the valve. When the current to the torque motor is reduced, the vent is closed. This increases the control pressure P3 and closes the valve. During engine shutdown, a compression spring opens the valve to the full open position. In the event of a loss of electrical power to the torque motor the valve fails to the closed position. The P2.7 HBOV is non-modulating fully open or fully closed. It is controlled by FADEC to provide surge margin during transient operation. The P2.7 HBOV is opened during rapid accelerations slams or in steady state if FADEC detects that the surge margin is inadequate with the P2.2 HBOV fully open. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.7 HANDLING BLEED OFF VALVE DETAIL BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P2.7/P3 CHECK VALVE The P2.7/P3 check valve prevents P3 air flowing back into the compressor at the P2.7 stage. The P2.7/P3 check valve is part of the environmental control system (ECS). The ECS uses either P2.7 or P3 air. If the P3 air is being used, the P2.7/P3 check valve will prevent backflow into the high pressure compressor. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P2.7/P3 CHECK VALVE DETAIL BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM AIR DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION CONTINUED P3 AIR SEPARATOR The P3 air separator removes contamination from the P3 servo air. In order to prevent contamination damage of the P3 servo inlet port, a centrifugal separator is used to remove dirt and dust from the P3 air. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P3 AIR SEPARATOR BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM CONTROL AND INDICATION GENERAL DESCRIPTION The air indication system senses compressor discharge pressure at the exit from the HP compressor and transmits this pressure as an electrical signal to the related FADEC. This signal is used for: • • • Engine NL decouple logic Bleed air control Surge recovery A transducer senses P3 air pressure and converts this pressure to a proportional electrical signal that is then sent to the FADEC. The FADEC uses this signal for the NL decouple logic and surge recovery. The FADEC also transmits it to the ECS ECU, for bleed air control. The function of the Air Indication system is performed by the: • • P3 Pressure Transducer P3 Transducer to Gas Generator Case Air Tube BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - AIR INDICATION SYSTEM SCHEMATIC BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR SYSTEM CONTROL AND INDICATION COMPONENT LOCATION AND DESCRIPTION P3 PRESSURE TRANSDUCER The P3 pressure transducer senses compressor discharge pressure at the exit from the HP compressor. The P3 transducer converts this pressure into a proportional electrical signal and sends it to the FADEC. The transducer is located on the cyclonic de-aerator. It is connected to the gas generator case by a stainless steel tube and to the FADEC through an electrical wiring harness. The P3 transducer is a 2 channel device. In the event one channel fails the other channel can fully provide the signal to the FADEC. BOMBARDIER DHC 8-400 (PWC PW150) ENGINE AIR - P3 PRESSURE TRANSDUCER BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK