Air Conditioning.docx

2A-21-10: General Air Conditioning The air conditioning system provides pressurized and temperature-controlled airflow to maintain a comfortable environment for the occupants of the aircraft and provides a source of equipment cooling. Hot pressurized air from an external air cart or the compress...

2A-21-10: General Air Conditioning The air conditioning system provides pressurized and temperature-controlled airflow to maintain a comfortable environment for the occupants of the aircraft and provides a source of equipment cooling. Hot pressurized air from an external air cart or the compressor section of the auxiliary power unit on the ground or the compressor section of the engines is cooled through a series of processes by the Environmental Control System (ECS) Air Conditioning Packs (ACPs), remixed with some of the high temperature bleed airto achieve the desiredtemperature, and then delivered throughout the airplane. Distribution ducts provide air to the cockpit, passenger cabin, and baggage compartment. The higher pressure of this airflow allows regulation of the ambient pressure within the airplane to maintain an air density comfortable for breathing even though the airplane may beatthe highest operating altitude limit of 51,000 feet. Cabinaltitude withinthe airplane is controlled by regulating how much of the pressurized conditioned air remains within the aircraft. The airflow leaving the aircraft is regulated by a Thrust Recovery Outflow Valve (TROV) that opens and closes in response to automatic or manualcommands to maintainthe desired cabinaltitude level. The air conditioning system is divided into the following operational subsystems: 2A-21-20: Airflow and Temperature Control System 2A-21-30: Pressurization Control System 2A-21-20: Airflow and Temperature Control System 1. General Description: The Airflow Control System is a combination of two independent systems, the right and left Air Conditioning Controllers (ACCs), and each controls its respective Air Conditioning Pack (ACP) (see Figure 1.Air Conditioning Pack Simplified Block Diagram). Airflow for the cockpit and cabinare provided by boththe left and right ACC. As adosed loop system, it provides the advantage of improved cabin comfort and optimizes the use of bleed air. The ACPs modify high temperature and high pressure bleed air drawn from the aircraft engines or APU. Either or both engines or the APU may supply the bleed air to the ACPs. Normally the APU is used as a bleed air source on the ground untilengines are started; after engine start each engine supplies bleed air to the corresponding side ACP (left engine to left ACP, etc.). Engine bleedair supplied to the ACPs istaken from the lower temperature and pressure 5111 stage and/or higher temperature and pressure 5111 stage of the engine compressor (see Figure 2. Airflow and Temperature Control Simplified Block Diagram). Under most operating conditions, 5111 stage bleed air pressure and temperature is adequate for airaaft systems operation.At low power settings, 8th stage air may be required to meet minimum pressure and/or temperature needs. When the pressure of the eighth stage air exceeds that of the 5t11 stage, a check valve closes to prevent eighth stage bleed air from enteringthe engine compressor through the fifth stage bleed valve. The bleed air from the engines in the supply manifold is controlled and regulated to 40 psi and 400"F ±10, or 500"F ±10 when only one engine is available for bleed air or with a single wing anti-ice selected ON. Engine bleed air entering the ACPs is regulated by Pack Inlet Valves (PIVs) to a lesser pressure of 35 psi (single ECS pack operation).If only one engine is available as a bleed air source, the PIV of the remaining engine opens to allow maximum possible inlet air (within the ACP compressor discharge temperature limit of 425"F). The ozone converters, located in the tail compartment, break down atmospheric ozone into oxygen. From there, scrubbed bleed air enters the ACP, first passingover the primary stage of an air to air heat exchanger. The heat exchanger uses ambient air drawn into a ram air scoop in the dorsal fin as a cool air source to initially reduce bleed air temperature. The turbine bypass valve provides an additional function at high altitudes. Above35,000 feet, cabinheatingrequirements are greaterthancabin cooling, and additional airflow is needed to maintain cabin pressurization. For these reasons the turbine bypass valve opens to allow a more direct path for much of the engine bleed air inthe final ACP output rather than routing all of the air through the turbine expansion cooling process. The modulated ACP airflow of both packs enters into a common cold air manifold for distribution to the aircraft interior. The cold air manifold is paired with a hot air manifold to provide sources of supply for mixing air of different temperatures toachieve adesired comfort level inthe cabinandcockpit. (Both the cold and hot air manifolds are located beneath the flooring at the aftsection of the passenger cabin.) The hot air manifold is supplied by two ducts that are connected to each of the ACP bleed air inlets downstream of the ozone scrubbers. The ducts supply air at a nominal temperature of 400"F to the hot air manifold for blendingwith conditioned air inthe cold air manifold. The aircraft interior is supplied with temperature blended air throughthree supply ducts: Cockpit supply duct Forward cabin supply duct (zone one) Aft cabinsupply duct (zone two) All three ducts are connected direcUy with the cold and hot air manifolds through trim air valves. The three trim air valves modulate the amount of hot air admitted into the supply ducts, warming the cold air to achieve the desired temperature at each supplied location. The addition of hot air by the trim air valves is controlled by temperature selector switches on the BLEED AIR I TEMP CONTROL panel on the cockpit overhead. The forward and aft cabin supply ducts are divided to supply each side of the cabinwith air outlets located in the cabin sidewalls at floor level.The cockpit supply duct is split to supply the pilot and copilot sides of the cockpit and are atfoot level near the rudder pedals. All three supply ducts are fittedwith baffled silencers to reduce airflow noise. A separate gasper duct, connected only to the cold manifold, supplies cold air to the cabin overhead side panel eyeball outlets. The airflow and temperature control is divided into the following subsystems: ACP controls Cabin and cockpit temperature controls Equipment cooling Description of Subsystems, Units and Components: Air Conditioning Pack (ACP) Controls: System operation is provided by two annunciator switches located on the overhead panel on the flight deck. Control switches for the left and right ACPs are located on the BLEED AIR I TEMP CONRTOL panel on the copilot side of the cockpit overhead labeled L PACK and R PACK (see Figure 3. Temperature Control PaneO. Above the pack switches are the bleed air source control switches that select options for ACP supply. Bleed air supply ducting includes an isolation valve that enables the APU to supply both ACPs, each engine bleed to supply the corresponding ACP (e.g. L ENG to L PACK) or for one engine to supply both ACPs. After setting the bleed air supply to the ACPs, selecting the L PACK and/or R PACK switch on signals the Air Conditioning Controller (ACC) (located behind a closeout panel in the forward left hand side of the baggage compartment) for that pack to perform the following: Open the ACP inlet valve and modulate bleed air intake to meet cooling demands Monitor the ACP ouUet temperature Monitor compressor outlet temperatures, reducingcompressor ouUet temperature by positioning the ACP inlet valve to minimum flow if temperature exceeds 425°F Monitor turbine inlet temperature,warming airenteringthe turbine by routing it through the reheater if inlet temperature falls to 75"F Monitor and open the compressor bypass valve if compressor discharge air pressure is too low Open the turbine bypass valve above 35,000 feet to increase airflow to the aircraft interior Provide maximum air output during single ACP operation Provide monitoring and fault information to the Monitor and Warning System (MWS) The ACCs are linked to the Modular Avionics Units (MAUs) over ARINC-429 connections for input and output information (the left ACC to MAU #1, right ACC to MAU #2). The ACCs obtain altitude, outside air temperature (OAT) and pack switch information from the Flight Management System (FMS) through the MAUs for ACP control functions (other information pertaining to bleed air status is also used). The ACCs communicate ACP health and status information back to the MAUs to be formatted for ASCB-D data sharing, including the Monitor and Warning System (MWS). If ARINC-429 data connection is lost, the ACCs use default settings for ACP operation to preserve system function. The default mode assumes an aircraft altitude of 15,000 feet and an Outside Air Temperature (OAT) of 0°C. ACP performance degradation in the default mode depends upon actual aircraft altitude and OAT - for instance, the turbine bypass valve will not open if the aircraft is above 35,000 feet, nor will additional cooling air to the electronic equipment racks be available. Indirect control of the ACPs is provided by the switches on the ENGINE START panel (see Figure 4. Engine Start Control Panel.) If the APU is supplying bleed air for the operation of the ACPs prior to engine start, selecting the MASTER CRANK or MASTER START switch ON will shut down the right ACP. Selecting the START L ENG or START R ENG switch to ON will shut down the left ACP. The OFF legend in each pack switch will illuminatewhile the ACPs are notoperating. The ACPs are shut down by the ACC dosing the inlet valve of each ACP. When the first engine start iscomplete,theleft ACP inlet valve will open andthe left pack will retum to normal operation. When the MASTER START switch is selected OFF, the right ACP will retum to normal operation. This ACP automatic switching function for engine starts is confined to ground operations by Weight-On-Wheels 0NQW) switch position to predude loss of pressurization during inflight engine starts. Ambient ram air is normally used only for cooling in the ACP heat exchangers, after which it is exhausted from the aircraft through the louvers on the aft rear section of the fuselage. Some operational circumstances may require use of ambient air within the aircraft rather than conditioned ACP air. In these instances, selecting the RAM AIR switch on the TEMP CONTROL panel to RAM will direct ambient air into the cold and hot air manifolds completely bypassing the ACPs. When the RAM AIR switch is activated, the ACPs will shut down and the aircraftwill immediately depressurize (the L PACK and R PACK switches will illuminate OFF). Circumstances that might dictate use of the RAM AIR switch are: Overpressurization due to loss of system control Smoke removal from the aircraft interior Ditching over water Cabinand Cockpit Temperature Control: The operation of the trim air valves, mixing hot manifold air with cold manifold air, controls the temperature of the air entering the cabin and cockpit. Temperature control selectors on the TEMP CONTROL panel on the cockpit overhead signal the Air Conditioning Controllers (ACCs) to adjust the trim air valves to add or reduce hot air input to achieve the desired temperature (see Figure 3.Temperature Control Panel). There is a rotary temperature control selector for each supply duct: COCKPIT, FWD CABIN and AFT CABIN. The function of each temperature control selector is controlled by the corresponding AUTO I MAN mode switch above the selector. In the AUTO mode, the temperature selector range is from 60°F degrees at the COLD setting to 90°F at the HOT setting. In the MAN mode, the temperature selector directly controls the position of the trim air valve through the ACC. When selecting temperatures in the MAN mode, the TEMP DISPLAY switch (described in the following paragraphs) should be selected to the DUCT position to avoid a supply duct overheat (at 215 ±15°F) or duct ice formation. LED temperature displays for the cockpit, forward and aft cabin are positioned above the AUTO I MAN mode select switches on the TEMP CONTROL panel. Each digital display may be selected to one of three readouts by using pushbuttons on the TEMP CONTROL panel: VVith the AUTO TEMP SELECT pushbutton set to ON, the temperature readouts display the desired temperatures set with the rotary temperature selectors for each of the three air conditioned areas (e.g.cockpit to 68°F, fwd cabin to 70°F and aft cabin to 72°F). VVith the AUTO TEMP SELECT pushbutton set to OFF (illumination extinguished), the TEMP DISPLAY pushbutton may be used to set the digital temperature readout to reflect the actual temperature in the air conditioned areas by depressing the button to the ZONE position (illuminated blue). VVith the AUTO TEMP SELECT pushbutton set to OFF and the TEMP DISPLAY pushbutton set to DUCT (illuminated green), the digital temperature readouts reflect the actual temperature in the supply ducts to the air conditioned areas, read from temperature sensors downstream of the trim air valves. The TEMP DISPLAY pushbutton alternates between ZONE and DUCT each time the button is depressed. Zone temperature readings are taken from temperature sensors that are positioned at variablelocations within each zone. Location of the sensors is dependent upon aircraft interior customization and not fixed in production aircraft. Each temperature sensor has a dedicated fan to circulate zone air over the sensor. There are no controls associated with the fans. The failure of temperature sensing information, auto temperature control circuits, trim air valves or a supply duct over-temperature will be sensed by the ACCs and a Crew Alerting System (CAS) message initiated prompting the flight crew to attempt manual control of zone temperatures. Equipment Cooling: Many electronic installations in the aircraft require a specific temperature range for optimum operation. Heat generated by electronic equipment must be dispelled to maintain the required temperature range. Cabin and cockpit conditioned air is used to cool equipment by ducting the airflow in the desired direction and/or fans mounted in equipment racks or integral to the equipment unit. There are five cooling fans installed as follows: L EER Fan R EER Fan L PSU Fan Forward Cabin Sensor Fan Aft Cabin Sensor Fan The LEER and REER each contain an electrically-powered, two-speed cooling fan. Below 35,000 feet, the fans operate at high speed. Above 35,000 feet, the ACC shifts the fans to low speed, provided both ACPs are operating. If only one ACP is available, fan speed remains high above 35,000 feet. The Left PSU fan pulls air through ducts in the passenger compartment that are fitted with eyeball outlets for passenger ventilation. The speed of the PSU fan also changes at 35,000 feet, but in the reverse of the EER fans - the PSU operates at low speed below 35,000 feet and shifts to high speed above 35,000 feet. The Left PSU duct exhaust is directed into the top of the LEER to assist equipment cooling. LEER airflow is routed through the equipment racks and over the Power Distribution Box (PDB) before exhausting through louvers into the area beneath the forward cabinfloor. The Transformer Rectifier Units (TRUs) are located in the compartment beneath the forward cabin floor and are cooled by the exhaust of LEER fan airflow. Airflow is assisted by an integral fan on each TRU. After passing through the underfloor compartment, the air is drawn upward into the bottom of the REER by the action of a cooling fan in the right PDB at the bottom of the REER. The underfloor air cools the PDB and mixes with the cooling air drawn into the top of the REER by the REER fan. The combined flow is then exhausted overboard through the Thrust Recovery Outflow Valve (TROV) that is located behind the REER. The TROV, sh01Nn in Figure 5. Pressure Relief Valve (PRV) and Thrust Recovery Outflow Valve (TROV), has a variable opening to control the rate at which the conditioned air exits the aircraft. Aircraft pressurization is controlled by varyingthe size of the TROV opening. If the TROV is fully open, the aircraft is not pressurized since the flow of ACP air is not restricted. As the aircraft climbs, the size of the TROVopening deaeases to retain more ACP conditioned air within the aircraft, aeating a pressurized atmosphere in the interior controlled via the TROV. The Baggage Compartment or AEER contains a single-speed cooling fan. The fan operates whenever the Left Main DC bus is powered and the fan circuit breaker is dosed. Each Display Unit (DU) has an integral fan that operates whenever the DU is powered. All EER fans are monitored for failure. Temperature sensors in the areas cooled by the fans provide indications of degraded operation resulting in equipment overheating. Any detected failure is displayed as a message on the CAS window. Controls and Indications: Airflow and temperature controls are depicted graphically on the ECS I Press synoptic 213 window display (see Figure 6. ECS 213 Synoptic Page).The synoptic window contains: The Cabin Pressurization Control System (CPCS) provides control,regulation and monitoring of the cabin pressure to ensure maximum passenger comfort and safety. The conditioned bleed air used for cabin air conditioning is also used for cabin pressurization. Pressurization control is accomplished by the modulation of the Thrust Recovery Outftow Valve (TROV), which is controlled by the Cabin Pressure Controller (CPC) in the normal operating mode. The primary function of the CPC is to limit the differential pressure across the aircraft fuselage. The dual-channel controller controls the rate of change of cabin pressure as well as the level of cabin pressure based on inputs from the Air Data Modules (ADMs) and the Flight Management System (FMS). If the FMS data is not valid, the controller shall use an auto schedule for control of the cabin altitude and rate. Cabin pressure control is accomplished via three modes of operation: Automatic Mode (AUTO): (See Figure 8. Pressurization Schedule (Automatic Mode).) In AUTO mode, the aircraft's data is used to provide pressure altitude, corrected barometric pressure and aircraft Landing Field Elevation (LFE). During AUTO mode, the CPC provides cabinpressure control via either oftwo identical control channels. Each channel commands an independent AC motor on the TROV. The AC motor (correspondi ng to the channel in control) is used to drive the TROV to control cabin pressure. VVhen one channel is in control during AUTO mode, the other channel is operating in standby mode. Both channels receive ARING 429 input from the aircraft avionics, as well as discrete signalsfrom the aircraft such as Weight-on-Wheels 0-NQW) and door dosed signals. Semi-automatic Mode (SEMI): (See Figure 9. Pressurization Schedule (Semi-Automatic Mode).) In SEMI mode, the crew has the ability to manually input aircraft cruise and cabin altitude, barometric correction, LFE and the rate of cabin dimb or descent via the copilot Standby Multifunction Controller (SMC). Thiscapability allows the flight crew to input this data in the event FMS data is not available or is invalid. Based on these inputs, the CPC then controls cabin pressure in the same manner as during the AUTO mode. Manual Mode (MANUAL): In the event that both AUTO mode channels in the CPC become inoperative, or when MANUAL is selected, the CPCS can function in MANUAL mode. In this mode, the flight crew hasthe ability to regulate cabin pressure by manually driving the position of the TROV. This is accomplished by selecting the FAULT/MANUAL switch on the Cabin Pressure Control Panel (CPCP) and rotating the MAN HOLD knob to the desired position for the TROV. Manual Mode control of the TROV is accomplished via an independent DC motor on the TROV. In MANUAL mode, cabin pressure information is provided to the flight crew by an independent Cabin Pressure Acquisition Module (CPAM) which is aseparate, stand-alone unit from the CPC. The CPAM calculates the cabin rate of ascenVdescent, cabinaltitude and cabin delta-pressure and provides this information via the ARINC 429 bus to the Cabin Pressure Indicator (CPI). The CPAM will also post cabin pressure CAS messages. In AUTO and SEMI modes of operation, information displayed on the CPI originates from the active channel of the CPC. Cabin pressure is affected by the thrust recovery outflow valve (TROV) position, and bleed air flow from the engines (derivative of throttle position). To avoid uncomfortable cabin pressure bumps, small activations ofthe CABIN ALT knob (usingonly half of the knob's full deflection)for short durations (one second or less) should be used. After each activation, pause and observe the resulting Cabin Rate of Change (ft/min). Targeting a rate of change between 500 and 1000 FPM is recommended for crew and passenger comfort. Smooth throttle movements will result in smooth cabin pressure changes. Oncethethrotues are atthe desired position, make appropriate changes using the CABIN ALT knob per the instructions above. Avoid abrupt throttle movements, if able. Cabin Pressure Control System (CPCS): The CPCS dual-channel digital controller is used to accomplish control, perform power-up and periodic Built-in Test (BIT) of allthe components in the CPCS. It reports test results and messages along the ARINC 429 data bus for display on the CAS, the 1/6 and 2/3 Environmental Control System I Pressure synoptic pages as well as provide component fault information to the Central Maintenance Computer (CMC) for later retrieval by the crew or maintenance personnel. The components of the pressurization system are: Cabin Pressure Controller (CPC) CABIN PRESSURE CONTROL panel Standby Mutifunction Controller (SMC) Thrust Recovery Outflow Valve (TROV) Cabin pressure indications Cabin Pressure Acquisition Module (CPAM) Baggage compartment shutoff and smoke removal valves Pressure Relief Valve (PRV) Description of Subsystems, Units and Components: Cabin Pressure Controller (CPC): The CPC is located in the REER.It is designed as a dual channel unit containingtwo identical channels. Each channel of the controller contains a microprocessor with an independent power source (115V AC) and an outflow valve motor driver. At any given time, only one channel is in control of sensing cabin pressure and commanding the TROV open or dosed. The CPC contains two ARINC 429 transmitters. Channel 1transmits the CABIN ALT, DIFF PRESS, RC (cabin rate-of-change [climb I descent]) and cabin pressure related warning messages to the Modular Avionics Unit (MAU) No. 1. Channel 2 transmits the same data to MAU No. 2. Channel 1 andchannel 2 also transmit CABINALT, DIFF PRESS and RC (cabin rate-of-change [climb I descent]) to the CPI. The CPC also receives cabin altitude data from the CPAM for comparison with its channels. During normal operation, cabin pressure information is received from the active channel of the cabin pressure controller and displayed on the CPI. If either of the channels become inoperative or the data becomes invalid, the CPI displays the cabin pressure information computed in the CPAM. The CPAM data will also be displayed when the pressurization system is in the MANUAL mode. The CPI provides digital presentations for cabin altitude and cabin differential pressure and a motor-driven analog cabin rate-of-change indicator. The CPAM does its own computing and has one ARINC 429 bus to the CPI. The data carried on ARING 429 buses consists of the following: Cabin rate-of-change Cabin altitude Differential pressure CABIN DFRN 10.80 CABIN DFRN 11.00 The CPAM outputs four discretes to the MAUs as follows: Three to MAU No. 1and one to MAU No. 2. The discretes to MAU No. 1 consist of the following: Cabin Pressure Low CABIN DFRN 11.00 CPAM Fail The discrete to MAU No.2 is for CABIN DFRN 10.80. The following are displayed on the 2/3 Summary synoptic page, 2/3 Environmental Control System I Pressure synoptic page and 1/6 Environmental Control System I Pressure synoptic page. Cabin altitude in feet Rate-of-change in feet Landing field elevation in feet Delta-P in psid MODE (Only displayed on 2/3 Environmental Control System I Pressure synoptic page) The CAS display messages are as follows: @i&j?ltDI (caution) Cabin Differential - 10.80 (caution)) Cabin Pressure Lo (warning) Cabin Differential - 1 1. 0 (warning) If the ARINC 429 buses from the CPC are available,the MAUs use them. If the ARINC buses are invalid or unavailable, the MAUs look to the discretes from the CPAM andthe display on the synoptic I system pages shows amber dashes. The CPAM Fail(amber) message displays anytime the CPAM fails regardless of ARINC 429 status. The MAUs pass CPAM Fail(amber) messages on to the CMC for storage. CABIN PRESSURE CONTROL Panel: (See Figure 10. Cabin Pressure Control Panel.) The CABIN PRESSURE CONTROL panel on the cockpit overhead provides pushbutton switches and a rotary (spring-loaded neutral) knob for pressurization mode selection and manual control. An indicator of TROV shutter position is also furnished. The pushbutton switches are illuminated toindicate the active pressurization mode. The FAULT portion of the FAULT I MANUAL pushbutton also serves as an indication of AUTO and SEMI mode failure. Selections on the panel enable the flight crew to perform and control the followingfunctions: Select the AUTO, SEMI or MANUAL mode of operation. Select the FLIGHT or LANDING mode of operation. Manually position TROV shutters to open or close, or to any intermediate position. Monitor the rate of TROV shutter movement. Standby Multifunction Controller (SMC): (See Figure 11.CPCS SEMI Mode - Standby Multifunction Controller (SMC).) The CPCSinterfaces with the standby SMC to receive flight crew selected aircraft/cabin altitude, LFE, barometric correction and cabin rate. The SMC receives the same data from the Cabin Pressure Controller (CPC) to display the selected data. The SMC provides the functionality of the cabin pressure selector panel. The capability of the SMC cabin pressure selector page differs based on cabin pressure mode selected: Automatic Mode: Input data provided by the FMS and Air Data System (ADS)input data are provided to the MAU which then gets provided to the CPC and SMC for viewing. Semi-Automatic Mode: Data are input via the SMC for the aircraft cruise I cabin altitude, barometric correction, LFE and cabin rate-of-climb I descent. Manual Mode: The CPAM provides FMS and ADS input data to the CPI for viewing. The SMC will dash out in the Manual mode. Note Commands received from the SMC are only received during Semi-Automaticmode and control cabin pressurization settings: cruise I cabin altitude, barometric correction display, landing field elevation and the cabin rate-of-climb I descent. Thrust Recovery Outflow Valve (TROV): The aerodynamic shape of the TROV has two opposable shutters mounted vertically within a square frame. The forward shutter pivots outward andthe aft shutter pivots inward to provide an opening to exhaust pressurized air. The size of the opening created by shutter movement controls aircraft pressurization. The shutters are positioned by one of three electrical drive motors (two AC and one DC). Linkages between the shutters ensure symmetrically opposite movement. The operatingdrive motor rotates a gear mechanism that moves the shutters. The design of the gears is such that positive motor input is required to move the shutters in either direction. This prevents shutter movement and loss of pressurization control in the event of electrical system malfunctions or failure. VVhen the CPC is operating inAUTO or SEMI mode either of the 115V AC motors is available to move the TROV shutters.Each motor is associated with one of the two CPC control channels (1 and 2). To preserve the longevity of the pressurization system components, the active channel switches with every flight CPC logic requires that the aircraft be on the groundwith weight on wheels, be fully depressurized for one minute with the TROV fully open before control channels swap - the logic avoids repetitive changes during touch and go landings). If the AC motor normally associated with the active control channel malfunctions, the CPC will automatically switch to the remaining AC drive motor. If a malfunction or failure of the 115V AC power system renders both motors inoperative, the CPC will signal the failure to the flight crew, prompting selection of MANUAL mode. In manual mode the DC motor positions the TROV shutters using switch commands directly from the cabin pressure control panel, bypassing the CPC. Failure of a single CPC channel is annunciated on the Crew Alerting System CAS) display window as a @Q'tfJiilm(advisory) CAS. Failure of both channels prompts a _ --_....;...._ ..:.. ·_IMU!if!! (caution) CAS message and illuminates the FAULT section of the FAULT I MANUAL pushbutton on the cabin pressure control panel. If the TROV malfuncti ons (independent of the operating control system) an [el!ji;Gzj d@tt!]p (advisory) CAS message is displayed. Cabin Pressure Indications: The cabinpressure is monitored with the indicator labeled CABINALT FT, located above the CABIN PRESSURE CONTROL panel. The indicator has digital displays for cabin altitude and cabin differential pressure. An analog dial displays cabin rate of change with a conventional needle pointer. Cabin Pressure Acquisition Module (CPAM): CPAM is located in the bottom section of the Right Electronic Equipment Rack (REER). It is a self-contained unit with a dedicated connection to the aircraft static pressure lines and an independent cabin pressure sensor. The CPC channels compare cabinpressure data. If a disagreement exists of greater than 310 feet, each channel compares with the CPAM. A disagreement of greater than 310 feet between the CPC channel and the CPAM causes that CPC channel to fail. When operating in MANUAL mode, only CPAM data is available for cabin pressure altitude and cabin differential pressure. CPAM data in manual mode is displayed in the digital cabin pressure indicators above the CABIN PRESSURE CONTROL panel. Note The use of manual pressurization will cause the c:c::m:I @¥Hl!iii!·N (warning) CAS message to be displayed at 10,000 feet cabin altitude. This is only true if both CPCS channels have failed. Baggage Compartment Shutoff and Smoke Removal Valves: (See Figure 12. Baggage Compartment Smoke Vent Valve.) The baggage compartment shutoff valve is a pressure differential (.l:i.P) operated diaphragm valve that prevents the deterioration of cabin pressure when the baggage compartment experiences a decompression. It also contains provisions for reopening the valve after the decompression condition has been corrected. Duringflight, the baggage compartment is pressurized. Conditioned air is routed through a baggage compartment shutoff valve into the baggage compartment. The shutoff valve will close at a differential of between 1.5 to 3.2 psi if the baggage compartment becomes depressurized. A (advisory) CAS message will be annunciated if a pressure differential reaches four psi between the cabin and the baggage compartment. The door separating the passenger compartment and the baggage compartment is normally closed unless access is required. When closed, the door acts as a secondary pressurized bulkhead. Since the baggage compartment is normally pressurized to a slighUy higher level than the passenger compartment to induce air flow, a split flapper vent valve inthe top left of the internal baggage compartment door allows the higher pressure airto into the cabin. The valve is hinged to allow airflow only into the cabin, and will close if the baggage compartment becomes depressurized to prevent loss of cabin air through the baggage compartment. The baggage compartment may be deliberately depressurized to remove smoke from the interior of the aircraft. A manually operated valve, installed above the baggage compartment access door on the cabinside, provides smoke removal. If smoke has been detected in the baggage compartment, the smoke evacuation valve handle may be rotated clockwise to the VENT I SMOKE position to remove smoke from the Internal Baggage Door CAS message color logic: Blue message anytime open belOIN 40,000 ft. Amber message anytime open above 40,000 ft.