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What bleed air port services the OBOGS system?
Left P3 port
What bleed air port services the heat, defog, pressurization and anti-G?
Right P3 port
What bleed air must pass through a heat exchanger?
- OBOGS, Anti-G, canopy seal
- all other ECS functions
Environmental control is on what bus?
Cooling air is supplied to the heat exchanger by what two methods?
How is the left P3 port bleed air controlled?
supply lever on the OBOGS regulator
With a/c on the ground, how is ventilation air provided?
blower activated by weight-on-wheels switches
What does the RAM AIR FLOW switch do?
- supplies fresh air ventilation
- Controls the FRESH AIR VALE
What two switches control bleed air into the cockpit?
- BLEED AIR INFLOW switch - inflow valve
- DEFOG switch - defog valve
- both on battery bus - INFLOW SYS
Amount of fresh air ventilation is controlled by what switch during ground and unpressurized flight (below 8000')?
- RAM AIR FLOW
- closed - OFF
- mid open - NORM
- full open - HI
What does the BLEED AIR INFLOW switch do?
Controls the position of the inflow valve and how much bleed air is supplied, if any
What does the TEMP CONTROL dial do?
- controls a motor-driven heat exchanger bypass valve
- diverts a portion of warm bleed air around heat exchanger to be mixed with cool air downstream - controlling cabin temp
Which sensors are connected to the TEMP CONTROL switch?
- rear cabin temperature sensor
- cockpit temperature control sensor
The TEMP CONTROL switch automatically controls cockpit temperature between ____-____.
At what duct temperature does the heat exchanger bypass valve close, and all bleed air is forced through the heat exchanger?
Inflow system is on what bus?
Defog air temperature is automatically maintained by the position of the _____ switch.
The air conditioning only operate when the:
- Engine is on
- Generator on-line
- AIR COND or DEFOG switch ON
Air conditioning blowers will produce _____ on the HI setting.
Air conditioning is powered on what bus?
generator; AIR COND
The pressurization control valve regulator is located in the ______.
aft pressure bulkhead
Starting at 8000', describe how the pressurization control valve maintains cockpit pressure altitude.
- CKPT PX is maintained at 8000' until a dif. pressure of 3.6 +/- 0.2 is reached at 18,069'
- 18,069-31,000' dif. pressure will be maintained at 3.6+/-0.2 at a cabin altitude of 16,600'
Cockpit dif. pressure is monitored by ______.
- delta P regulator (differenctial pressure regulator)
- Aft pressure bulkhead
What keeps the solenoid bump valve open when on the ground?
Weight-on-wheels switch removes power from the solenoid, leaving the valve open
What does the DUMP position do on the pressurization switch do?
- removes electrical power to the solenoid dump valve; depressurizes the cockpit
- bleed air continues to flow
- ram air is not provided
What does the RAM/DUMP position do on the pressurization valve?
- removes power from the solenoid dump valve; depressurizes cockpit and allows ram into the cockpit at the same time
- DEFOG is automatically turned off
If the BLEED AIR INFLOW switch is OFF, and the RAM/DUMP is selected, what happens?
an increase in ram air flow into the cockpit will occur
amber CKPT PX
cockpit pressure differential pressure exceeds 3.9-4.0 psi
The safety valve receives a signal from the dif. PX regulator if the cockpit dif. PX exceeds ____psi
Anti-G: a safety valve in the flow line automatically relieves pressure if it exceeds _____ psi.
How does the anti-G valve work?
as +G's increase, a rod moves downward exposing more of the orifice which allows more PX in to the G-suit.
How does the OBOGS monitor oxygen concentration?
automatically for the current altitude
what does a plenum do?
functions as a holding tank between OBOGS unit and regulators
red OBOGS FAIL
- occurs whenever there is low bleed air pressure before the concentrator
- Before engine start
- Loss of bleed air
amber OBOGS TEMP
temp in OBOGS ducting exceeds 200F
At the end of the three minute OBOGS test, what does it mean if the red OBOGS FAIL light is illuminated?
OBOGS failed the test
OBOGS bit test
- allows ambient air into the system dropping the O2 concentration, thus illuminating the OBOGS FAIL light
- when valve closes, concentration returns to normal, annunciator should go out
What bleed air system incorporates a water separator?
What does placing the DEFOG switch to ON do?
- defog valve is opened, increasing bleed air supply
- inflow valve is automatically set to high, increasing bleed air supply
- A/C compressor is automatically turned on drying the air
- An ejector downstream draws ambient cockpit air into the ECS system, increasing volume
How long does it take to close the defog valve, DEFOG switch off?
up to 40 sec
What climb performance can be expected with DEFOG on?
a reduction up to 47% in FLAPS UP climb performance
Having DEFOG on does what to ITT?
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