Environmentals Flashcards
How is cockpit air heated and cooled
Heated by condition bleed air
Cooled by vapour cycle system using an engine driven compressor
Where are the environmental controls located
Front cockpit right side console
Power is provided through which circuit breaker located where
CKPT TEMP
FWD Cockpit Generator panel
The heat exchanger is divided into two sections what goes through each section
Anti-G, OBOGS and canopy seal
All other Enviros functions
Where is bleed air tapped from for ECS and what’s is it used for
P3 left - OBOGS
P3 Right - canopy seal, anti-g, heating/defogging and pressurisation.
What two sources of cooling air is supplied to the heat exchanger.
Blower on the ground thru weight on wheels
Ram in flight
Which two switches control the position of the bi-level flow control shutoff valve (inflow valve)
Bleed air inflow switch on ECS panel
Defog switch on centre console
What two switches must be off to prevent P3 bleed air from entering the cockpit
Bleed air inflow switch
Defog switch
What CB is power provided through for the bi level flow control and shut off valve (inflow valve), and Bi level flow control bypass valve (defog valve).
INFLOW SYS CB on fwd cockpit batt bus panel.
What position is the inflow valve in if air con compressor is operating and the aircraft is below 7500 flat MSL and why
Automatically closed. It improves cooling performance by eliminating warm bleed air into the cockpit.
When the defog switch is set to on what is the position of the Bi-level flow control shutoff valve and why
Fully open
To maximise the volume of bleed air entering the cockpit
Where are the two overtemp sensing sources downstream of the heat exchanger located and what are the temperatures and indication
Rear distribution valve aft of the front ejection seat
Duct just aft of the firewall
300*F
Amber DUCT TEMP eicas message
What is shut down when the firewall shut off handle is pulled
Hydraulic system
Fuel system
Environmental system
Briefly describe the operation of the anti-G system
A weighted rod covers an orifice at nil g conditions but as G is encountered the rod moves down opening an orifice to allow engine bleed air to inflate the g-suit. The more gs encountered the more of the orifice is exposed allowing more bleed air in and proportionally inflating the g-suit
What switch controls the canopy seal/anti-g shutoff valve
Bleed air inflow valve
Where is power for the canopy seal/anti-g shutoff valve provided from
CB placarded INFLOW SYS on batt bus CB panel in fwd cockpit.
Canopy seal/anti-g shutoff valve is de-energised_________
Closed
What component in the canopy seal/anti-g system protects the anti-g valves from contamination
Water seperator
Explain how the anti-g test button tests the system.
When the button is pressed the weighted rod is depressed to allow bleed air to flow into the suit
Where is bleed air for heating and defogging tapped off from?
RH p3 port
What valves are used to route bleed air for heating and defogging
Bleed air inflow valve (bi level flow control and shutoff valve)and defog valve (bi level flow control bypass valve).
How is air for heating and defogging routed in the cockpit
Via the Vent control lever placarded Air located on the centre console in fwd cockpit only
How is air for heating and defogging distributed in they cockpit
Via the defog outlets and foot warmers
The vent control lever mechanically controls what valves in the air ducts
The butterfly valves
At what temp is the air entering the cockpit automatically controlled to
60 - 90 deg F
What switch allows you to control cockpit air temp and where is it located
Temp control switch on the environmental control panel in fwd cockpit right switch panel
Which portion of the temp control switch is used for auto temp control
Auto portion works on a potentiometer
Briefly describe the operation of the temp control switch in the manual position
Moving the temp control switch to the 6 o’clock position where it is spring loaded toward null position. Moving the switch left or right towards hot or cold manually changes the position of the heat exchanger bypass valve
What does the temp control switch recieve its inputs from
Temp control sensor located in the duct between the two cockpits, the temp control rheostat position and the cabin temperature sensor located on the rear pressure bulkhead.
What happens if the temp controller detects a temperature in excess of 165 deg F
It directs the the heat exchanger bypass valve to move to full closed forcing max bleed air through the heat exchanger.
Where is power for the temp controller provided from
CB placarded CKPT TEMP located on the generator bus circuit breaker panel in the front cockpit.
What four things does placing the defog switch to on do
Defog valve is opened increasing the bleed air supply
The inflow valve is set to high further increasing the the amount of bleed air entering the cockpit
The aircon compressor is automatically turned on to dry the air
An ejector downstream of the heat exchanger takes the bleed air and passes it through a venturi (jet pump) drawing ambient air into the ecs ductingfurther increasing the volume of air available for defogging.
If the defog switch is placed to off how long does the electrically controlled defog valve take to close
Up to 40 seconds
What effect does operation of the canopy defog have on the engine and why
Increases ITT for a given PCL setting because of higher bleed air load on engine
During a flaps up climb With defog on and PCL retarded to maintain ITT within limits, how is performance affected.
There is a reduction in performance of up to 47%
Name the 5 components of the pressurisation system
Control valve Safety valve Control valve regulator Differential pressure regulator (delta p regulator) Solenoid dump valve
What two valves combine to provide pressure control
Control valve
Control valve regulator
In what position is the dump solenoid de-energised
Open
What two valves operate together to give redundant control of max diff
Differential pressure reg (Delta p regulator)
Safety valve
Is the dump solenoid energised or de-energised with weight on wheels
De-energised open
What cockpit altitude is maintained until a cockpit diff pressure of 3.6+/- 0.2 psi
8000 ft
At what altitude is max diff reached
18069 ft
What is the cockpit pressure altitude at 31000ft
16600ft
At what cockpit pressure altitude does an amber CKPT ALT caution illuminate on EICAS
At or above 19000ft
At what cockpit press diff does a red CKPT PX EICAS message illuminate
3.9 - 4.0 psi
Where is the pressurisation control switch located
ECS panel
What are the three positions of the pressurisation control switch
Norm
DUMP
Ram/dump
In what position does the temp control switch control pressurisation automatically
NORM
What does selecting DUMP on the pressurisation control switch do
Removes power from the solenoid opening the control valve mechanically, however bleed air inflow continues
What does selecting the RAM/DUMP switch do
Opens the fresh air valve
Closes the defog valve if open
However bleed air inflow continues unless the bleed air inflow continues
How is cockpit and avionics cooling achieved
Vapour cycle system
How is the vapour cycle system controlled
By a toggle switch placarded AIR COND located on the ECS panel on RH fwd cockpit switch panel
In what two circumstances would the vapour cycle system be operating
With the AIR COND switch on
With the DEFOG switch to on
What four conditions must exist for AIR COND to operate
Engine running
Generator is on line
Gen bus is powered
AIR COND or defog switch is on
When must the evap blowers be on
Whenever avionics master switch is on
What will interrupt electrical power to the compressor clutch should there be abnormally high or low system pressure
Bi level pressure switch located in the service panel just forward of the right wing.
What effect does air cond operation have on engine performance.
Negligible, air cond can be operated for all takeoffs landings and ground operations
What switch controls the fresh air valve during ground ops and unpressurised flight
RAM AIR FLOW on ECS panel in front cockpit
What bus supplies electrical power to the fresh air valve
Hot battery bus
What are the three positions of the Fresh air valve
Closed, mid open and full open which corresponds to the Off, Norm and Hi positions of the Ram Air Flow switch
At what altitude is the fresh air valve automatically closed
Approaching 8000 ft to allow the cockpit to pressurise
Where does air for OBOGS operation come from
Bleed air from LH P3 port
What obogs component provides a limited supply of oxygen in the event of obogs failure
Plenum
What factors is the obogs plenum supply based on
Cockpit pressurisation
Aircraft pressure altitude
Pilot regulator settings
Pilot demand
Where is oxygen supplied from in the event of obogs failure
Ejection seat emergency oxygen supply
What component allows the pilot to breath cockp[it ambient air should obogs fail
Antisuffocation valve
What bus provides power for the obogs system
Hot battery bus
Will obogs operate in the event of engine failure
No
What are the indications of an obogs concentrator malfunction resulting in the production of zeolite dust
Respiratory irritation
Coughing
Presence of white dust in the oxygen mask
What 3 failures can a red OBOGS Fail EICAS message indicate
Low bleed air pressure upstream of the concentrator
Low concentration of oxygen
Internal OBOGS failure detected by BIT
An OBOGS FAIL EICAS message has displayed on start and then extinguished, what has occurred and can you continue the sortie
The upstream low pressure switch has detected no pressure and extinguished as the line pressurised on start. This is normal and sortie can be continued.
Will a failure be detected in the OBOGS system when first activated
Not for first 3 minutes as the OBOGS FAIL warning is inhibited during a 3 minute BIT
At what temperature does the OBOGS TEMP EICAS illuminate if an overheat is detected in the OBOGS ducting
200 deg F
How can the oxygen pressure regulator be gang loaded to provide high oxygen content pressurised breathing in the event of hypoxia symptoms or loss of cabin pressure
Place the supply lever to on
Concentration lever to MAX
Pressure lever to emergency
What action is required to disable the OBOGS system
Oxygen supply lever in both cockpits must be off
