ATA 21 Air Conditioning - Bombardier DHC 8-400 (PWC PW150) PDF

BOMBARDIER DHC 8-400 (PWC PW150) ATA 21 - AIR CONDITIONING TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM Cabin temperature can also be selected using the switches...

BOMBARDIER DHC 8-400 (PWC PW150) ATA 21 - AIR CONDITIONING TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM Cabin temperature can also be selected using the switches on the flight attendant panel. INTRODUCTION The air conditioning system has the following subsystems: The air conditioning pack supplies the flight compartment and cabin air distribution systems with conditioned air. The conditioned air is used for cabin and flight compartment heating, cooling, ventilation and pressurization. GENERAL DESCRIPTION • • • • Air Distribution Cooling Temperature and Indication Control Pressurization Control The air conditioning system takes bleed air from each engine and delivers it to one integrated pack containing two Air Cycle Machines (ACM), distribution and recirculation air systems. Air required to operate the system is supplied by each engine from high or low pressure bleed ports. On aircraft equipped with an Auxiliary Power Unit (APU), bleed air is available from the APU when the aircraft is on the ground. An optional ground air conditioning connection is available to supply conditioned air from a ground source. Conditioned air is supplied to the cabin through upper and lower vents in the ceiling and sidewalls. Conditioned air is supplied to the flight compartment through the sidewalls. The gasper system provides air to the individually controlled air outlets in the cabin, flight compartment and lavatory. The recirculation system draws air from the cabin zone and routes it back to the mixer, where it is mixed with air discharged from the Air Cycle Machines. The conditioned air from the ACM pressurizes the aircraft. Pressurization is controlled by regulating the amount of air leaving the aircraft. An avionics cooling system supplies cooling for the avionics equipment bay and the EFIS/ESID liquid crystal displays. Air temperature is independently controlled for the cabin and flight compartment and can be controlled either automatically or manually. Cabin and flight compartment temperatures are selected using the switches on the AIR CONDITIONING control panel on the flight compartment overhead console. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 2 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - ECS SIMPLIFIED BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 3 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM AIR DISTRIBUTION PURPOSE The distribution system has these functions: • • Divides conditioned air to the two airplane zones Supplies air to electronic equipment The air conditioning (ECS) packs supply the flight compartment and cabin air distribution systems with conditioned air. The conditioned air is used for cabin and flight compartment heating, cooling, ventilation and pressurization. The air distribution system takes conditioned air from the ECS packs and distributes it to the flight compartment, the passenger compartment and the toilet. Rigid, semi-rigid and flexible ducts are used in the distribution system. The ducts are routed under the cabin floor and have separate distribution systems for the cabin and the flight compartment. Conditioned air is supplied from: • • • Ground supplied conditioned air (optional) Two air cycle machines Recirculation system The conditioned air is distributed to the cabin through lower dado panel vents, overhead vents and passenger gaspers. A recirculation fan helps to boost the supply of conditioned air. A gasper system distributes air to individual outlets in the cabin, flight compartment and the lavatory. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 4 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - CABIN AIR DISTRIBUTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 5 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM FLIGHT COMPARTMENT AIR DISTRIBUTION PURPOSE Conditioned air is also distributed to the flight compartment through lower vents near the rudder pedals, through side console gaspers and selectable vents for side window de-misting and to the aft baggage compartment. An avionics cooling system cools the avionics equipment bay and the EFIS/ESID liquid crystal displays by drawing heated air away from them. On aircraft with the ground air conditioning connection (8215000071): • An optional ground air conditioning connection is available to supply conditioned air from a ground source. Cabin and flight compartment temperatures are selected using the switches on the AIR CONDITIONING control panel on the overhead console. Cabin temperature can also be selected using the switches on the flight attendant panel. Caution lights indicate excessive temperatures in the Air Cycle Machine (ACM) compressor discharge and in the cabin or flight compartment supply ducting. The flight compartment conditioned air distribution system supplies the flight crew with conditioned air. Conditioned air is supplied to the flight compartment to maintain a comfortable environment. Conditioned air for the flight compartment is also used for side window de-misting and aircraft pressurization. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 6 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - FLIGHT COMPARTMENT AIR DISTRIBUTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 7 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM FLIGHT COMPARTMENT AIR DISTRIBUTION GENERAL DESCRIPTION Air supply to the flight compartment is ducted from the air conditioning pack, through the rear pressure bulkhead, to the left side of the splitter duct. From the splitter duct, the flight compartment air is ducted along the right side of the aircraft below the cabin floor. Before reaching the flight compartment, the distribution system also supplies conditioned air to the aft baggage compartment inlet, forward lavatory gasper and the forward flight attendants gasper. SUB-SUB-SYSTEM DESCRIPTION At the flight compartment bulkhead, a “Y” duct splits the airflow into two individual but identical distribution systems, one for the pilot side and the other for the co-pilot side. In the flight compartment, the distribution system has lower level and upper level outlets. The upper level outlets are de-misting nozzles for the pilots and co-pilots side windows. The lower level outlets include a foot warming piccolo tube near the rudder pedals, a fixed grille near knee height and a large torso gasper. Flow control levers located near the window sill allow the pilot and co-pilot to control the flow of air into the flight compartment. A small manually controlled gasper at window height is also supplied. SUPPLY DUCTS The air conditioning pack supplies conditioned air through its supply ducting to a fitting in the rear pressure bulkhead. Forward of the pressure bulkhead, the flight compartment and cabin flows are separated by the splitter duct. An outlet on the left side of the duct supplies flight compartment air and an outlet on the right side of the duct supplies cabin air. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 8 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - SPLITTER DUCT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 9 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM FLIGHT COMPARTMENT AIR DISTRIBUTION SUPPLY DUCTS A supply duct routes the conditioned air from the splitter duct to the flight compartment bulkhead. The duct is located below the cabin floor on the right side of the aircraft. In addition to supplying the flight compartment, the duct supplies the aft baggage compartment inlet and the forward lavatory and flight attendant gaspers. A duct branches from the main flight compartment duct at station X743 and supplies the aft baggage compartment inlet. Two solenoid valves are installed; one at the inlet to the baggage compartment and the other at the outlet grille. These solenoid valves control the ventilation of the baggage compartment. Aft of the flight compartment bulkhead at station X-18, a duct branches off from the main duct. This duct then divides into a duct which supplies the forward lavatory gasper and a duct which supplies the forward flight attendant gasper. Aft of the flight compartment bulkhead station X-39 on the right side of the aircraft, the supply duct divides into two ducts. These ducts penetrate the bulkhead and supply the left and right side flight compartment distribution systems. The left and right side distribution systems in the flight compartment are identical to each other. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 10 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - FLIGHT COMPARTMENT AIR SUPPLY DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 11 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM FLIGHT COMPARTMENT AIR DISTRIBUTION SUPPLY DUCTS Forward of station X-54, a duct branches off to supply the side window de-mist system. A manual damper valve is installed in this duct at floor level. A flow control lever located at shoulder height regulates the quantity of air flowing through the valve. The airflow from the damper valve is then directed to the side windows through three composite de-mist nozzles installed at the window sill level. A shut off valve is installed below the flight compartment floor forward of station X-69.4. This valve controls the flow of air to the torso gasper, fixed sidewall grille duct and the foot warming piccolo tube. A dedicated flow control lever located at shoulder height regulates the quantity of air flowing through the valve to these outlets. Between stations X-54 and X-69.4, a duct branches off from the supply duct. This duct supplies a shoulder height small gasper. The small gasper is controlled at its outlet since the supply duct is not regulated by the damper valve. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 12 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - FLIGHT COMPARTMENT AIR DISTRIBUTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 13 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION CABIN AIR DISTRIBUTION SUB-SUB-SYSTEM DESCRIPTION PURPOSE The air distribution, cabin and baggage compartment has the following: The passenger cabin conditioned air distribution system divides the flow of conditioned air to the passenger cabin upper and lower duct systems INTRODUCTION • • • • • Distribution Damper Recirculation Fan Recirculation Fan Switch Splitter-Distribution Duct Distribution-Noise Treatment Duct Conditioned air is supplied to the cabin to maintain a comfortable environment for the passengers and crew. Conditioned air is also used for aircraft pressurization. GENERAL DESCRIPTION Air supply to the cabin is ducted from the air conditioning pack into the fuselage at the centre of the rear pressure bulkhead. The air is then ducted under the baggage compartment floor, where it splits into an upper and lower supply duct for each side of the fuselage. The lower duct supplies air to the dado panel vents, while the upper duct supplies air through sidewall risers to the overhead vents and gasper system. The Environmental Control System Electronic Control Unit (ECU) monitors a supply duct temperature sensor, an overtemperature switch and a cabin temperature sensor as part of the control loop. Cabin ducting supplies air to: • • • • • • PSU gaspers Sidewall downwash Ceiling up-wash Dado panels Galley gaspers Lavatory gaspers TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 14 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - CABIN AIR DISTRIBUTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 15 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION DISTRIBUTION DAMPER PURPOSE The Distribution Damper is used to adjust the amount of air being delivered to the upper and lower duct systems. DESCRIPTION The distribution damper is installed just aft of station X604.5. It is an electronically controlled and electrically actuated valve with a 7 inches/177.8 mm diameter inlet and two 6.5 inches/165.1 mm diameter outlets. The left hand side supplies the upper distribution system, for the cooling mode. The right hand side outlet supplies the lower distribution system, for the heating mode. The upper outlet duct supplies the Passenger Service Units (PSU) gaspers, the sidewall downwash and the inboard ceiling up-wash. The lower distribution duct supplies the dado panels. The right digital channel of the ECU automatically sets the distribution damper depending on the cabin zone supply temperature sensor. During heating, 70% of the warm air goes to the lower vents and 30% to the overhead vents. During cooling, 70% of the cool air goes to the overhead vents and gaspers and 30% to the lower vents. During standard temperatures, 50% of the air is directed to the overhead vents and 50% to the lower vents. The right digital channel of the ECU controls the electric motor of the distribution damper valve. If the right digital channel or the electric motor fails, the damper valve will remain in its last position. Faults are logged in the non volatile memory of the ECU and sent to the CDS. Two position switches in the damper valve send discrete signals to the ECU indicating whether the valve is in the full warm or the full cool position. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 16 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - DISTRIBUTION DAMPER TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 17 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION RECIRCULATION FAN PURPOSE The recirculation fan draws air from the passenger cabin and returns it to the mixing box in the air conditioning unit, re-introducing it into the conditioned air flow. DESCRIPTION The recirculation fan, located on the right side of the air conditioning pack, draws cabin air through the Recirculation Filter that is located between the rear wall of the baggage compartment and the rear pressure bulkhead. The recirculation ducting contains a check valve that prevents reverse flow through the fan in flight or during pack operation. The recirculation fan on/off switch on the flight deck air conditioning panel controls the on/off operation of the recirculation fan. The recirculation fan has two speeds (controlled by the ECU digital channel in command). The fan starts operating at the slow speed. This is to prevent excessive current draw. Power (28V DC) is supplied through a 100 amp fuse from the main distribution box located in the nose section TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 18 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - RECIRCULATION FAN TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 19 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION RECIRCULATION FAN CONTROLS AND INDICATIONS The recirculation fan toggle switch is located on the AIR CONDITIONING control panel in the flight compartment. The switch controls the ON/OFF operation of the fan. When the switch is set to the RECIRC position, the fan starts at slow speed to reduce initial current draw and it then changes to a high speed. It also operates at slow speed during single ACM operation. Fan speed is controlled by the ECSECU. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 20 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING CONTROL PANEL RECIRCULATION FAN OPERATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 21 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION SUPPLY DUCTS The air conditioning pack supplies conditioned air through its supply ducting to a fitting in the rear pressure bulkhead. Forward of the splitter duct, at station X763, there is an aluminium section of the cabin supply ducting. The zone supply overtemperature switch and the two zone supply temperature sensors are located in this section of the ducting. After supplying the aft galley gasper and the aft flight attendant gasper, the cabin supply duct divides in two at the distribution damper. The left side of the damper supplies the upper cabin distribution duct which is routed under the cabin floor on the left side of the aircraft. The right side of the damper supplies the lower cabin distribution duct which is routed under the cabin floor on the right side of the aircraft. The upper cabin distribution duct supplies the Passenger Service Unit (PSU) gaspers and the sidewall downwash and ceiling up-wash vents. The lower cabin distribution duct supplies the dado panels. The upper cabin distribution duct has a main supply duct. The risers which branch off the main duct supply air to the large PSU bins. The supply air to the smaller bins located at the extreme forward and aft end of the cabin interior. Each riser divides into two smaller (“Y”) ducts before entering the PSU. One duct supplies the sidewall downwash/ceiling up-wash chamber while the other duct supplies the PSU gasper chamber. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 22 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - CABIN AIR DISTRIBUTION DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 23 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION SUPPLY DUCTS The sidewall downwash refers to the air that flows down the sidewall of the cabin interior. This air flows out of small holes located along the bottom of the downwash/ up-wash chamber behind the PSU bin. The ceiling up-wash refers to the air that flows up towards the ceiling of the cabin interior. This air flows out of upward facing ducts connected to each end of the downwash/up-wash chamber. These ducts are located between the PSU bins. Air entering the PSU gasper chamber supplies the individual passenger controlled gaspers. The lower cabin distribution duct has a 6.5 inches/165.1 mm main supply duct which reduces to a 5 inches/127 mm diameter duct. Small (1.5 inches/38.1 mm) risers branch off the main duct to supply the dado panel (elbow) inlets. The shape of the elbow inlet causes the air to flow fore and aft into the dado panel which forms a chamber for the dado panel outlets. The dado panel outlets are a fixed angle outlet 30° towards the floor with adjustable flow control louvers. The cabin ducts are insulated with a fibreglass blanket. The insulation is then wrapped with an aluminized tedlar film. The 2 inch diameter bin riser ducts are only insulated below the inter-costal. This is, so that, in the heating mode the internal duct temperature will moderate before entering the gasper or downwash chambers. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 24 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - CABIN AIR DISTRIBUTION DETAIL 2 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 25 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION SUPPLY DUCTS DISTRIBUTION - NOISE TREATMENT DUCT PURPOSE The distribution noise treatment duct reduces the overall cabin noise coming from the Air Cycle Machines (ACM). DESCRIPTION The duct is installed in the cabin supply ducting between station X664.5 and X683.5. The distribution noise is reduced by the air being forced through the duct that is a perforated aluminium tube surrounded by an insulating material and silicone impregnated glass cloth. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 26 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - NOISE TREATMENT DUCT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 27 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION WASTE AIR PATH The primary waste air path, for conditioned air that is not collected by the recirculation system, or leaks directly overboard, is through the outflow valve of the Cabin Pressure Control System (CPCS). The outflow valve is located on the aft pressure dome above the level of the aft baggage compartment floor. A waste path of at least 155 in² is provided in order to limit the residual cabin pressure to -150 ft. when the outflow valve and the safety valve are open. The waste air flows through the seat rail grille and under the cabin compartment floor until frame station X 714.602. Aft of X 714.602 the majority of the waste air will flow through the inter-costal and around the aft cargo compartment. The waste air must flow around the aft cargo compartment, since there is virtually no open area below the floor level at the canted frame, X829.542/836.452 and the low leakage rates of the aft cargo compartment prevent waste air flow through the aft cargo compartment bulkheads and liners. In order to provide the required waste air path, a nominal 1 inch gap is left between the inboard face of the frames from X714.602 to X829.542/836.452 and the aft cargo compartment liner. Also, the insulation just below the inter-costal is sculpted away from the inter-costal lightening holes, to provide a low resistance flow path to under the cabin floor. The CPCS outflow valve exhausts into the unpressurized aft equipment bay. The waste air then flows out of the aircraft through the aft equipment bay access panel. This panel is a louvered grille with an open area of 155 in². TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 28 of 214 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 29 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM GROUND CONNECTION SUPPLY DUCTS PURPOSE The ground connection provides a way of supplying conditioned air to the Environmental Control System (ECS) when the aircraft is on the ground. GENERAL DESCRIPTION An external source of conditioned air is attached to the ground connection. Conditioned air flows through the ground connection and its ducting to the air conditioning supply ducts. The ground connection system has the following components: • • • Ground Connection Ground Connection Check Valve Ground Connection Ducts SUB-SUB-SYSTEM DESCRIPTION An external air supply source is connected to the aircraft ground connection. Ducts carry the conditioned air from the ground connection point to the cabin and flight compartment supply ducts. The ground connection system has a check valve located in the ducting. The check valve is held in the open position by the air pressure from the external air supply source. ECS supply system ducting carries the conditioned air to the cabin and flight compartments. The check valve is held in the closed position by a spring when there is no pressure. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 30 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK/GROUND CONNECTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 31 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION GROUND CONNECTION PURPOSE The ground connection lets an external source of conditioned air, supply the aircraft air-conditioning system on the ground. DESCRIPTION The ground connection is a duct accessed through the external air conditioning door. The door is circular shaped, hinged and sealed, located at the rear fuselage right hand side. The connection point has a cover to prevent outside contamination from entering the system. The ground connection duct has a check valve to prevent system pressure discharging overboard when the ECS is operating using bleed air, or during emergency ram ventilation. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 32 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - GROUND CONNECTION DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 33 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION UNIT(S) GROUND CONNECTION CHECK VALVE PURPOSE The ground connection check valve prevents dirt from entering and loss of air back through the Ground Air Connection. The check valve is a 5 inches/127 mm diameter, aluminium, dual flapper valve. The check valve is installed in the ducting between the ground connection point and the air conditioning pack. During flight, the check valve prevents pressurized air from the air conditioning packs or the emergency ram air system from venting overboard. When there is no pressure available, the check valve is held closed by a spring to prevent dirt from entering the system. GROUND CONNECTION DUCTS PURPOSE The ground connection ducts provides a direct path to the aircraft air conditioning system for the external conditioned air. The ground connection ducts carry conditioned air from an external supply source to the air conditioning supply ducts for the flight and cabin compartments. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 34 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - GROUND CONNECTION CHECK VALVE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 35 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION RAM AIR PURPOSE The emergency ram air system supplies unconditioned air to the flight and cabin compartments in the event of a failure of the air conditioning pack. GENERAL DESCRIPTION The emergency ram air system comprises a duct connected between the pack heat exchanger ram air inlet plenum and the pack conditioned air outlet duct. It includes a check valve at the outlet connection, to prevent reverse flow during normal operation of the pack: • • Check Valve Ram Air Ducts SUB-SUB-SYSTEM DESCRIPTION The function of the emergency ram air system is to: • Supply emergency ram air to the cabin and flight compartments in the event of a failure of the air conditioning packs In flight, ram air enters the aircraft through the NACA vents at the base of the dorsal fin. It flows through the ram air ducting to the dual heat exchanger where it cools the bleed air entering the air conditioning packs refer to 21-51-00. If there is no air flow from the air conditioning packs, the pressure from the ram air is enough to overcome the spring in the ram inlet check valve. The check valve will open allowing ram air to flow directly into the flight compartment and cabin supply ducts. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 36 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - RAM AIR SYSTEM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 37 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION UNIT(S) RAM AIR CHECK VALVE PURPOSE The ram air check valve prevents loss of conditioned air back through the ram air ducting during pack operation and provides Emergency Ram Ventilation in forward flight when two packs are off. The ram air check valve is a circular, 5 inches/127 mm diameter, dual flapper valve. It is spring-loaded to the closed position. The valve is installed between the upper and mid emergency ram air ducts and provides essential ventilation in flight when the pack is not operating. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 38 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - RAM AIR CHECK VALVE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 39 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION UNIT(S) RAM AIR DUCT PURPOSE The Ram Air Duct carries emergency ram air to the flight and cabin duct system. A series of ducts carries the emergency ram air to the flight and cabin compartments distribution system. The emergency ram air ducting starts at the aft side of the ram air inlet duct. The air is ducted down and then forward between the two ACMs to the front of the air conditioning pack. The ram air ducting then joins the conditioned air supply duct at a tee connection just upstream of the splitter duct. The tee connection then distributes the emergency ram air to the cabin and the flight compartments. RAM AIR INLET CHECK VALVE PURPOSE The Ram Air Inlet Check Valve allows additional air flow across the dual heat exchanger during ground operations. The valve closes to prevent loss of ram air flow from the NACA vents during flight modes. The Ram Air Check Valve is a spring loaded, dual flapper device. The air flow is created by the fans on the air cycle machines. If the air cycle machines are operating at maximum speed on the ground, more air is demanded than can be supplied by the NACA vents. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 40 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - RAM INLET CHECK VALVE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 41 of 214 BOMBARDIER DHC 8-400 (PWC PW150) • • • • AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION Avionics and Display Cooling Fan Speed Control-Fan Unit Zone Temperature Switches Low Speed Warning Detector AVIONICS COOLING PURPOSE The system removes heat around equipment in the avionics and wardrobe racks and heat from the five liquid crystal display units on the flight compartment instrument panel. This improves the reliability and availability of the avionics systems. The avionics cooling system has two independent duct networks and three fans. GENERAL DESCRIPTION The aircraft has an extraction type cooling system for the avionics equipment racks and for the liquid crystal displays (LCD) found in the five Display Units (DU) on the flight compartment instrument panels. Control of the system is automatic and requires no pilot action for both normal and abnormal operation. The cooling system has three identical fans, which pull heated air from equipment. Each fan can supply half the required cooling flow. Failure of any fan is recorded in the Central Diagnostic System (CDS) for further maintenance action. There is no indication of a single fan failure to the flight crew. Only two of the three fans are required to be operational for dispatch. Failure of additional fans are annunciated to the flight crew by a FANS FAIL message displayed at the bottom right corner of the Engine Display (ED). The electrical and ducting systems have been designed so that single failures do not result in the loss of the DUs. The avionics cooling system has these components: TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 42 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AVIONICS AND LCD COOLING SYSTEM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 43 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AVIONICS COOLING SUB-SUB-SYSTEM DESCRIPTION The avionics cooling system has dual redundant duct assemblies. Each duct assembly has a cooling fan and branches that are connected to and remove heat from the: • • • 5 Display Units (DU) Avionics Rack Wardrobe Rack LOCATION One of the two duct assemblies is routed from Fan 1, below the cabin floor, to the instrument panel on the pilot side. It is also routed behind the avionics rack and wardrobe shelf. The other duct assembly is routed from Fan 2, below the cabin floor, to the instrument panel on the co-pilot side. The duct assembly on the co-pilot side contains the Standby fan (Fan 3), which is located below the flight compartment floor near the co-pilots seat. Each duct assembly alone can supply enough cooling for continuous operation of the DUs. The hot air is exhausted into a duct that directs the air to the rear of the baggage compartment liner. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 44 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AVIONICS EQUIPMENT AND DISPLAY UNIT COOLING SYSTEM DUCTS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 45 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AVIONICS COOLING SUB-SUB-SYSTEM DESCRIPTION GENERAL Fan 1 and Fan 2 are running whenever the electrical power is applied to the aircraft 28V DC main bus. If either of these fans fail, the standby fan (Fan 3) automatically starts operating. Each fan, operating at high speed mode (HSM), supplies one half of the required air flow. When the standby fan takes the place of the failed fan, the cooling system becomes fully operational again. Operation of the fans is inhibited on the ground when the flight compartment temperature is below 41°F/5°C. In case of electrical power failure, when only the battery power is available, Fan 1 operates at low speed and Fan 2 turns off. If Fan 1 is not available, Fan 2 operates at low speed. The standby unit (Fan 3) is not available when the main buses are not powered. This operational mode is capable of supplying the minimum air flow required for the DU to operate at reduced brightness. With minimum air flow and reduced brightness, the DU will operate with higher internal temperatures, but below the automatic shutoff threshold. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 46 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AVIONICS COOLING ELECTRICAL SCHEMATIC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 47 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM requirements while still meeting the battery loading requirements. The standby fan (Fan 3) is not available when operating on battery power. CABIN AIR DISTRIBUTION NORMAL FAN OPERATION AVIONICS COOLING Two of the three fans operate in High Speed Mode (HSM) when either of the following conditions are true: AVIONICS COOLING FAN AND LOW SPEED WARNING • • • DETECTOR The fans extract heated air from the avionics equipment and the DUs. FAN FAILURE The avionics cooling fans also supply a constant flow of air across the flight compartment zone temperature sensors. GENERAL The avionics cooling fan has an electronically controlled, two speed, brushless DC motor. There are three fans, Fan 1, Fan 2 and Fan 3, which supply airflow in the two avionics cooling ducts. When DC generated power is available and the aircraft is in flight Weight Off Wheels signal, the fan speed control unit operates as follows: • • • WOW, and DC power is available, and flight compartment temperature is >5°C or, W OFF W, and DC power is available Three fans available, two fans operating at HSM Two fans available, two fans operating at HSM One fan available, one fan operating at HSM Failure of any fan is recorded in the Central Diagnostic System (CDS) for further maintenance action. There is no indication to the flight crew of a single fan failure. Each fan has a built-in electronic Low Speed Warning Detector (LSWD) which sends a signal to the Input/Output Module (IOM) when the fan is rotating slower than 5000 rpm. The IOM uses the low speed warning signal to record and display faults. The IOM continuously monitors the fans for signals from the LSWD. Both IOM 1 and IOM 2 monitor all three fan fail outputs. SPEED CONTROL-FAN A fan speed control unit is installed on the side wall of each of the three avionics cooling fans. At start-up, electrical power is supplied to all three fans. If there is no fan fail signal from the LSWD, Fan 3 will shut down and Fan 1 and Fan 2 will operate in High Speed Mode (HSM). This is to ensure that a hidden failure does not exist in any of the three fans. POWER FAILURE OPERATION If only battery power is available, the system automatically selects an operational fan (Fan 1 or Fan 2) based on signals from the LSWD. The selected fan operates from battery power at Low Speed Mode (LSM). A fan operating at LSM can supply enough airflow to meet the avionics and LCD cooling TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 48 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AVIONICS AND LCD COOLING FANS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 49 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AVIONICS COOLING ZONE TEMPERATURE SWITCHES PURPOSE The two zone temperature switches control fan operation depending on the flight compartment temperature. They also control the recording of fan failures in the CDS system. Each avionics cooling fan has a connection to one of two zone temperature switches located under the DUs. These switches inhibit the fan operation on the ground, when the flight compartment temperature is below 41°F/5°C. This allows the LCD internal heater to operate during cold day starts without interference from the fans. The temperature switches are disabled by a relay if the Weight On Wheel (WOW) signal indicates that the aircraft is airborne. Each zone temperature switch has a second section which sends a signal to the Input Output Module (IOM). The signal causes the IOM to inhibit the recording of a fan failure by the CDS when the temperature is below 50°F/10°C. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 50 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - ZONE TEMPERATURE SWITCHES TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 51 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AVIONICS COOLING CONTROLS AND INDICATIONS There are no manual controls for the avionic cooling fans. The avionics cooling system status is indicated on the Engine Display and/or Caution and Warning Panel. ONE FAN FAILURE Single fan failures are logged within the CDS and are not shown to the flight crew. TWO FANS FAILURE (AIR MODE) If the aircraft is in the air, the FANS FAIL advisory message is displayed on the Engine Display (ED). TWO FANS FAILURE (GROUND MODE) If the failure of two fans occur while on the ground and speed is less than 50 Kts, the FANS FAIL advisory message is displayed on the Engine Display (ED) to inform the pilot that dispatch is not permitted. At the same time, the IOM turns on the AVIONIC caution light on the Caution and Warning Lights Panel. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 52 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AVIONIC COOLING FANS MALFUNCTION INDICATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 53 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AVIONICS COOLING INTERFACES LOW SPEED WARNING DETECTOR Each fan has a built-in electronic Low Speed Warning Detector (LSWD) which sends a signal to the Input/Output Module (IOM) when the fan is rotating slower than 5000 rpm. The IOM uses the low speed warning signal to record and display faults. The IOM continuously monitors the fans for signals from the LSWD. Both IOM 1 and IOM 2 monitor all three fan fail outputs. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 54 of 214 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 55 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM the APU FADEC based on EGT. CABIN AIR DISTRIBUTION SUB-SYSTEM DESCRIPTION COOLING The cooling system has these sub-systems: • • PURPOSE Air Conditioning Pack Flow Control System The cooling system supplies the airplane with a regulated flow of conditioned air. The left and right air conditioning packs supply the cooling air. The air conditioning system supplies the desired flow of conditioned air to the aircraft air distribution system. The air is conditioned to the proper temperature and humidity required to maintain a comfortable environment for the crew and passengers. GENERAL DESCRIPTION The air conditioning pack is part of the Environmental Control System (ECS). It is located in the aft fuselage immediately behind the rear pressure bulkhead. It is installed onto the structure with struts and vibration isolators. Mount straps retain pack position when some of the vibration isolators are disconnected for component maintenance. The ECS uses bleed air from the engines or Auxiliary Power Unit (APU) to supply conditioned air to the cabin and flight compartment. The system responds to flight crew commands and compartment temperature controls to supply a comfortable temperature environment for passengers and crew. The flow control system uses pressure and temperature data to control the flow of the bleed air that enters the air conditioning pack. The Electronic Control Unit (ECU) opens and closes the pack flow control and shutoff valve to regulate the flow of bleed air as a backup control for engine bleed air (primary control is at the nacelles). It is also the primary control for APU bleed air backup is in TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 56 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK AIRFLOW TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 57 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION AIR CONDITIONING PACK PURPOSE The air conditioning pack conditions the bleed air to the proper temperature and humidity and delivers it to the air distribution system for environmental control of the cabin and flight compartment. • • • • • • • • • • • • Turbine Shutoff Valve (2) Fan Bypass Check Valve (2) Ram Outlet Check Valve (2) Ram Inlet Check Valve Temperature Reduction Shutoff Valve Air Conditioning Pack Ducts Air Conditioning Pack Struts Air Conditioning Pack Mounts Valve-Temperature Reduction Switch Compressor Over-temperature Switch Compressor Outlet Temperature Sensor (2) Outlet Temperature-Secondary Heat Exchanger Sensor GENERAL DESCRIPTION The air conditioning pack is part of the Environmental Control System (ECS). It uses bleed air from the engines or Auxiliary Power Unit (APU) to supply conditioned air to the cabin and flight compartment. The system responds to flight crew commands and compartment temperature controls to supply a comfortable temperature environment for passengers and crew. Two air cycle machines (ACM), with one dual heat exchanger located in the aft fuselage, cool the bleed air coming from the two engines. This configuration provides the redundancy of two packs while allowing access to a much larger dual heat exchanger during operation with a single ACM. The air conditioning pack has the components that follow: • • • • • • • • Heat-Dual Exchanger Condenser/Reheater/Mixer Spray Nozzle Water Collector Air Cycle Machine (2) Fan Inlet Diffuser Housing Pack Bypass Valve (2) Compressor Inlet Check Valve (2) TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 58 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK FLOW BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 59 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM The primary-cooled bleed air then divides into two air flow paths which pass through two compressor inlet check valves one check valve for each air flow path to the compressors of both Air Cycle Machines (ACM). CABIN AIR DISTRIBUTION The ACM compressors increase the temperature and pressure of the incoming bleed air. The two compressor outlet flows combine into one flow at the secondary part of the dual heat exchanger. Two compressor outlet temperature sensors one for each compressor outlet measure the compressor outlet temperatures. AIR CONDITIONING PACK SUB-SUB-SYSTEM DESCRIPTION The air conditioning system is started by selecting BLEED 1 and/or BLEED 2 switches on the AIR CONDITIONING control panel, or the BL AIR switchlight on the APU CONTROL panel. These switch settings determine the selection of the bleed air source, manual or automatic ECS operation and air flow rates for the flight and passenger compartments. With the air conditioning PACKS switch set to AUTO, and BLEED 1 & 2 selected the bleed air comes from the left and right engines. With pilot and crew switch selections made, the ECS Electronic Control Unit (ECU) measures temperatures, pressures, and flow rates and uses this information to adjust valve positions in the ECS to get the selected conditioned air temperatures and flow rates (refer to 21-61-00). The ECU uses this compressor outlet temperature to reduce the flow as temperature increases. The ECU performs this function by modulation of the Pack Flow Control and Shut Off Valve (PFCSOV). A compressor outlet overtemperature switch monitors the combined compressors temperature. The switch activates on rising temperature and signals the ECU to close the turbine shutoff valve and the Pack Bypass Valve. If the switch is still activated after a time delay, the ECU closes the PFCSOV. The heat exchanger uses ram air to remove heat from the compressed bleed air. A secondary heat exchanger temperature sensor monitors the cooled bleed air as it leaves the secondary heat exchanger as a monitor of heat exchanger effectiveness. The ECU controls the two Nacelle Flow Control and Shutoff Valves (NFCSOV) to regulate the air flow to the air conditioning pack. The ECU sets the two NFCSOVs to get an equal bleed air flow from each engine refer to 36-11-00. Bleed air passes through the open pack flow control and shutoff valve to the air conditioning pack. The ECU receives the pressure and temperature data of the bleed air from the pack inlet absolute pressure sensor and the pack inlet temperature. The ECU uses this data to control the flow of bleed air through the pack flow control and shutoff valve during APU operation. As soon as the bleed air flows into the air conditioning pack, it passes through the primary part of the dual heat exchanger. The primary heat exchanger uses ram air to remove some of the heat from the bleed air. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 60 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK SCHEMATIC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 61 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM The bleed air expands as it passes across the turbine. The expanding air spins the turbine to supply the mechanical power to rotate the ACM compressor and fan. CABIN AIR DISTRIBUTION The temperature of the expanding bleed air greatly decreases to become the conditioned cooled air for the flight and cabin compartments. The volume of the expanding air increases and the pressure decreases. SUB-SUB-SYSTEM DESCRIPTION AIR CONDITIONING PACK The cooled bleed air from the secondary heat exchanger passes through the reheater and then to the condenser. The condenser, mixer and reheater are all part of the Condenser/Mixer/Reheater unit. The expanded air from both turbines and hot bleed air from the Pack Bypass Valve enters the mixer which combines with air from the recirculated air from the cabin. This air exits through the condenser and is then passed to the cabin and flight compartment distribution systems. The condenser is a heat exchanger which uses the cooler air from the ACM turbines to remove enough heat from the bleed air. This decrease in temperature causes water vapour in the bleed air to condense. The bleed air with condensed water vapour then passes to the water collector. The water collector uses centrifugal action no moving parts to remove the condensed water from the bleed air flow. The water in the collector then passes out through a water line to a spray nozzle attached above the dual heat exchanger. The high pressure of the bleed air forces the water out of the nozzle as a spray. The spray nozzle has two functions: • • Evaporates the water sprayed into the air flow to increase the efficiency of the heat exchanger Discards the water into the ram air flow which gets exhausted out of the aircraft Dried bleed air from the water collector then passes through the reheater another heat exchanger. The reheating of the bleed air vaporizes any condensation that gets past the water collector. The reheater uses secondary heat exchanger outlet air for heating. Bleed air from the reheater divides into two streams. Each air stream passes through a fully open turbine shutoff valve to an ACM expansion turbine. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 62 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK SCHEMATIC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 63 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM TEMPERATURE REDUCTION CABIN AIR DISTRIBUTION Under certain operating conditions, when HP (P3) engine bleed air is being used, it will be necessary to cool the engine bleed air that is delivered to the pack. The digital channel in control is responsible for operating the single Temperature Reduction Shutoff Valve. This valve is commanded open if the Pack Inlet Temperature Sensor indicates that the temperature is too high. Once it is commanded open, the Temperature Reduction Shutoff Valve will be kept open until the Pack Inlet Temperature Sensor indicates that the temperature is sufficiently low. SUB-SUB-SYSTEM DESCRIPTION AIR CONDITIONING PACK The ECU controls the two Pack Bypass Valves to regulate the temperature of the conditioned air sent to the cabin and flight compartment. These valves pass a portion of the warmer and higher-pressure bleed air taken before the dual heat exchanger to the outputs of each ACM expansion turbine. Opening the Pack Bypass Valve increases the flow of warm bleed air into the turbine outlet. This raises the temperature of the air supplied to the flight or cabin compartment. Closing the Pack Bypass Valve decreases the flow of warm bleed air into the turbine outlet. The Temperature Reduction Switch will trip and send a signal for BIT logic if the inlet temperature does not decrease when the Temperature Reduction Valve is commanded open. BIT logic will be able to detect failures associated with the temperature reduction control. Each digital channel has its own discrete input for the Temperature Reduction Switch and its own temperature sensor input for Pack Inlet Temperature. Both digital channels share control of the Temperature Reduction Shutoff Valve. This controls the temperature of the air supplied to the flight and cabin compartments. Bleed air, bypassed by the Pack Bypass Valves, also raises the humidity of the very dry conditioned air sent to the flight and cabin compartments. Each ACM turbine drives a fan which keeps the ram air flow through the dual heat exchanger at acceptable levels. This becomes necessary when the aircrafts speed cannot generate enough ram air flow through the dual heat exchanger such as when the aircraft is on the ground. When the aircraft is airborne, the ACM fans can limit the flow of ram air. As the flow of ram air increases, the ram air pressure on the fans increases. This increasing pressure opens two bypass valves in the ram air outlet ducts to permit the maximum flow of ram air. A recirculation fan takes air from the cabin to mix with the conditioned air from the ACM turbines. A RECIRC switch turns the recirculation fan on or off. Operating conditions determine the automatic control of the recirculation fan speed. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 64 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK SCHEMATIC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 65 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 66 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 67 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 68 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - AIR CONDITIONING PACK DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 69 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION HEAT-DUAL EXCHANGER PURPOSE The dual heat exchanger is used to cool the engine bleed air, to levels compatible with the ACM and system performance requirements. The dual heat exchanger is an aluminium plate-and-fin, primary cross-flow/ secondary counter-flow heat exchanger. It provides primary cooling of the pack inlet air and secondary cooling of the air from the ACM compressors. The dual heat exchanger is mounted at the top of the air conditioning pack between the ram air inlet duct and fan inlet diffuser housing. Vibration isolators on the left and front of the unit provide support and location for the top of the pack. A handle is provided front and back to assist manoeuvring the unit during maintenance. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 70 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - DUAL HEAT EXCHANGER LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 71 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION CONDENSER/REHEATER/MIXER PURPOSE The condenser is used to condense the water out of the cabin supply air prior to entering the turbines. The reheater is used to raise the temperature of the air entering the turbine. The mixer is used to combine recirculated air from the passenger compartment and air from the two turbine exit ducts. The condenser/reheater/mixer is located at the bottom of the air conditioning pack. The condenser/reheater/mixer is a dual turbine/single recirculation inlet with a bifurcated condenser outlet. The condenser/reheater/mixer is a cross-flow, plate and fin, aluminium heat exchanger. It has three air circuits. The condenser circuit receives warm, moist ACM compressor air from the secondary heat exchanger. The mixer circuit contains the cool air from the ACM turbines and the recirculated air from the cabin and flight compartment. The air in this circuit is cool enough to condense the water vapour from the surrounding air. The condensed water then goes to the water collector. After passing through the condenser, this air in the mixer circuit is delivered to the cabin and flight compartment. The reheater circuit contains the air that is downstream of the water collector. This air is reheated before it is delivered to the ACM turbine inlet. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 72 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - CONDENSER/REHEATER/MIXER DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 73 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION SPRAY NOZZLE PURPOSE The spray nozzle is installed on the top left side of the ram air header duct. The spray nozzle increases the heat sink by spraying water that has been removed from the system on to the cold face of the secondary heat exchanger. The nozzle sprays water against the ram air inlet face of the dual heat exchanger. This water evaporates and improves the efficiency of the heat exchanger. Removal of the water from the system is important for extending the life of the air cycle machine. If the water cannot be removed from the air before it enters the ACM turbines, it causes turbine nozzle erosion and imbalance, which degrades ACM performance and decreases its reliability. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 74 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING - SPRAY NOZZLE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 21 - AIR CONDITIONING Issue 6 - January 2023 Page 75 of 214 BOMBARDIER DHC 8-400 (PWC PW150) AIR CONDITIONING SYSTEM CABIN AIR DISTRIBUTION WATER COLLECTOR PURPOSE The water collector removes free water from the bleed air flow at the high pressure, hot side condenser outlet. The water collector is installed on the left side of the condenser and removes water from the bleed air. It has swirl vanes which use centrifugal action to push the condensed water to its inside walls. The water go