PC-21 Oxygen System Flashcards
What is the purpose of the oxygen system?
- To supply the aircrew with oxygen enriched breathing gas from engine start through all phases of aircraft operation, including ejection
- Protects the aircrew from inhaling noxious and toxics fumes during an emergency.
What is a disadvantage of the system?
Pilot loses the ability to smell invisible fumes that are an early indication of a potential problem.
What does it mean when the oxygen system is self-contained?
No cockpit air is breathed once the mask is fitted and the oxygen system has been turned on.
What are the two sub systems of the oxygen system?
- OBOGS - primary source of breathing gas for the aircrew during normal operations
- Emergency Oxygen (EO) - supplies oxygen to the aircrew during ejection from a cylinder fitted to the ejection seat.
What are the main components of the OBOGS?
- Heat exchanger
- OBOGS Pressure Reducing Shut-Off Valve
- Overpressure and overtemperature switches
- Water separator
- Oxygen Concentrator
- Solid State Oxygen Monitor Controller
- Oxygen hoses
What does the heat exchanger do?
Reduces temperature of incoming bleed air and passes cooled air to the PRSOV
What does the PRSOV do?
Controls the air pressure at a preset level
What does the overpressure switch do? Overtemperature switches?
- If PRSOV fails to control the air pressure, the switch will sent a signal to close the PRSOV and stop the airflow.
- Same thing if air is too hot
What does the water separator do?
Removes water from the air that is passed through
What does the Oxygen concentrator do?
Comprises of 3 oxygen concentrator beds that transform cooled, dried bleed air into oxygen enriched breathing gas.
What is the SSOM-C?
- It constantly monitors and controls the % of oxygen ini the output breathing gas
- Monitors air pressure in the cockpit
What is the primary function of the oxygen regulator?
- Reduces the pressure of the breathing gas to a suitable level for breathing.
- Maintains constant positive pressure differential in order to prevent breathing air contamination if there is a leak in the system
What controls does the oxygen regulator have?
- OXY switch
- Test pushbutton
- Mixture switch
What does the anti-suffocation valve?
Allows the pilot to breathe when the OBOGS is not operating.
What are the main components of the anti-g system?
- Anti-g valves
2. Connector assemblies
What is the function of the anti-g system?
Supply cool air to the pilots anti-g suits.
What are the main components of the EO system?
- EO cylinder
- Emergency Regulator Connector (ERC)
- EO regulator
- EO handle
- EO pressure gauge
What does the ACS shutoff lever do?
- Used to mechanically close the firewall shut-off valve in order to prevent air from flowing into the cockpit air distribution system
- OBOGS PRSOV is closed
- OBOGS and anti-g systems no longer function
What does OBOGS interface with to allow for warnings to be displayed on MFDs? What about DWP
Mission Computer (MC) RIOC 3
What provides power to oxygen regulators?
28V DC from BATT BUS
What does the OXY switch ON/OFF do?
When On:
- Power is supplied to SSOM-C, which in turn supplies power to the OBOGS concentrator
- OBOGS PRSOV is opened to provide engine bleed air
- Internal regulator valve is opened to pass breathing gas to the pilot
What is the TEST pushbutton used to ?
Used to check leakages of breathing gas at the face seal and from the flexible hoses.
What does the MIXTURE switch do?
- AUTO (normal position)
- MAX (generates max oxygen to both pilots)
Where is OBOGS schematic shows?
MFD ECS
What does the oxygen indicator show?
- White = taking a break
- Black = Not flowing
- Constantly black = pilot not breathing.
Before engine start, what should oxy and mixture switch be set to? After engine start?
- OFF
- AUTO
- After start, OXY switch to ON.
What occurs when OXY switch is set to ON after engine start?
OXY test will take between 3-5 mins, oxy warning will display.
When does the OBOGS operate at max capacity?
Above 15,000 ft
When should MAX be switched to?
- Aircraft operating consistently at high altitudes
- Evidence of hypoxia
- Stressful situations, such as aerobatic maneuvers or emergency situations
What factors affect the duration of the EO supply?
- Cabin altitude (increase in altitude increases the duration)
- Breathing rate (decreasing in breathing rate increases duration)
Under what situations would EO handle be operated in flight? How can it be activated?
- OBOGS fails
- Engine is shut down
- Pulling the EO2 handle
What does a red OXY OFF caption in MFD, red OXY caption on DWP, amber NO ANTI G mean?
Oxygen system is turned off.
What does a red OXY warning on DWP, MFD Warnings and red OXY BIT caption on MFD ECS mean?
SSOM-C power up or continuous built in test detects a failure
What does a red OXY warning on DWP, MFD WARNING, and a low LOW OXY caption on MFD ECS mean?
Oxygen pressure or concentration is low.
What does a red OXY warning on DWP, MFD, red OXY FAIL and amber NO ANTI g on MFD ECS page mean?
Oxygen system is shut down due to a critical failure, over-temperature or overpressure
What does a red OXY FLOW on MFD WARN and red OXY FLOW MFD ECS page mean?
Oxygen flow indicators remain in the same state, flow or no flow, for > 30 seconds
What does an amber OXY SENSOR on MFD mean caption mean?
System temperature or pressure sensor fails
What does an amber NO OXY ALERTS caution on MFD, amber EICAS caution and grey RIOC 3 FAIL advisory on the MFD
- RIOC 3 failure
- No oxygen system temperature and pressure sensor alerts are available.
What should be done in the case of smoke or fumes in the cockpit?
- EO supply activated
- ACS shutoff lever pulled
