Environmental Control System Flashcards
Primary purpose of the ECS
To route compressed air from the SDC, mounted on the Midwing Gearbox (MWGB), to the ECU, located aft in the left sponson, for use by the pneumatically supported primary and secondary environmental systems.
3 Parts of the Environmental Control System
- Air Conditioning2. Avionics Cooling3. OBIGGS/OBOGS
SDC
Shaft Driven Compressor - Mounted on the MWGB, is the primary air supply source
What can power the SDC
Either the APU or the main drive system
ECU
Environmental Control Unit - Conditions air for distribution to the cockpit and/or cabin.
OBOGS
Onboard Oxygen Generating System - converts partially conditioned air supplied by the ECU into oxygen-enriched air in order to support unpressurized flight at altitudes above 10,000 feet MSL.
OBIGGS
Onboard Inert Gas Generating System - Converts partially conditioned air into Nitrogen Enriched Air (NEA) for distribution to the fuel cells. The nitrogen atmosphere within the fuel cells has an inerting effect that reduces vulnerability to fire and explosions, but it is not a fire suppression system.
OBIGGS System Pressure
Supplies 40 psi at sea level and decreases to no less than 20 psi at the aircrafts operating limit of 25,000 ft DA
Rate and output pressure of the SDC
Supllies air to the ECU at 42 pounds per minute with an output pressure of 52.8 psi.
SDC Magnetic Chip Detector
Provides signal to the Avionics Bay Interface Unit (ABIU) resulting in an SDC FAIL caution
SDC Solenoid Valve
Controls oil flow to the Inlet Guide Vanes (IGV) and the Hydraflow Surge Control Valve (SCV). It is normally closed and opens when the ECS is ON.
SDC Oil pressure sensor
Provides a signal to the CMS for a low oil pressure indication of less than 20 pounds per square inch gauge (psig).
SDC Input Drive Shaft
Engages the MWGB to the SDC at approximately 12,000 rpm.
ECS Controller
Monitors the SDC for low oil pressure, low oil level, magnetic chips, and ECU ducting leakage, while controlling the air distribution throughout the cockpit and cabin through fan and valve operations
Heat Exchangers
Provide a means in which heated compressed air from the SDC can be cooled to the desired temperature
ECU Shutoff Valve
Regulates airflow to the Primary Heat Exchanger
Emergency Vent Fan and Check Valve
Supplies unfiltered ambient air to the cockpit and cabin in the event of an ECU failure
OBOGS has ___ outlets and is designed to be used by up to ___ personnel
7; 4
Emergency Oxygen
Backup oxygen supply from Emergency O2 bottle in case of OBOGS failure
Amount of Oxygen in Emergency O2 system
400 liters
Duration of Emergency O2
Enough to support 4 crewmembers for 3 minutes
Normal operating pressure of Emergency O2
2100 psi
When will LOW OXYGEN Advisory be displayed
when Emergency O2 pressure falls below 1800 psi
How can Emergency O2 be operated in the event of an electrical failure
The valve can be opened using the manual button located on the emergency oxygen control valve.
How does the pilot control the ECS
Through the dedicated ECS function key on the CDU keyboard
SDC FAIL Caution
- Low SDC oil pressure and APU engaged, 2. Low SDC oil pressure and Nr > 82%3. SDC chip detected.
Failure of the SDC will cause:
loss of OBOGS/OBIGGS, ECS, wing de-ice, and avionics particle separator scavenge air
What Triggers ECS AUTO TEMP FAIL Advisory
- Cabin temperature sensor failure2. Cockpit temperature sensor failure
ECS DISTRIBUTE FAIL Advisory
Indicates failure of the ECS proportioning valve or [C] the cockpit flow control valve has failed.
What triggers SDC INOP Advisory
- SDC solenoid failure2. Inlet guide vanes and/or surge control valve fail to move to proper position
What should be avoided in the event of ECS SDC LEAK
- Icing conditions below -4 degrees C2. Altitudes above 10,000 ft
What triggers AVIONIC BAY HOT Catution
Bay temperature above 130 degrees F
What Conditions trigger AVIONIC COOLING FLT Advisory
- Inlet fan failure 2. Exhaust fan failure 3. Inlet filter clogged 4. A drop in cooling air pressure
What trigger LOW NITROGEN Caution
O2 content above 9%
What triggers LOW OXYGEN Caution
O2 below 30% in the OBOGS output or that the breathing supply is inadequate and no compressed air is available.
Where is the ECU located
In the aft section of the left sponson
What can provide compressed air to the ECU during ground operations
Pneumatic power cart
Swivel duct assembly
Maintains compressed air to the ECU during wing stow operations by providing rotation of the ECS ducting through the midwing pivot point
Which BUS provides electrical power to the ECS Controller
No. 3 DC Bus
Particle Separator
Filters air, removing dirt and debris from air entering the Primary Heat Exchanger and scavenges filtered debris overboard
Primary Heat Exchanger
Cools compressed air entering the ECU to the compressor inlet of the ACM
Secondary Heat Exchanger
Cools ACM Compressor discharge air
Auxiliary Heat Exchanger
Lowers air temperature to improve performance of the water extractor and increases turbine outlet air temperature to provide additional heating capacity
Reheater/Condenser Heat Exchanger
Raises the temperature of turbine outlet air above freezing, requiring less additional heated air to prevent ice from forming in the condenser
Proportioning Valve
Determines the relative proportion of total airflow going to the cockpit and the cabin based on the selected temperature
Recirculation fan
electrically driven fan located in left hand cabin supply duct that provides an enhanced flow of cockpit exhaust air into the cabin distribution system
ECS in AUTO Mode
Pilot enters cockpit and cabin temperature between 54-84 degrees F
ECS in MANUAL Mode
Allows selection of cockpit airflow between 25-100%, and temperature 35 and 201 degrees F
Central Integrated Checkout (CIC) System
Tests ECS system for faults and records them on the brick, and generates warning, caution, and advisory messages
Emergency Oxygen Relief Valve
Opens if system pressure exceeds 2,500-2,700 psi
