Pressurisation Flashcards
How can the outflow valve be controlled?
2 Normal AC AUTO controllers
1 Manual DC Manual controller
What is our target cabin differential pressure?
8.6Psi
What does a cabin pressurisation above 8.6psi indicate?
Non normal. Cabin failing to maintain optimum
If the FO is managing the pressurisation controller, how would the system be configured?
AUTO 2
In Auto what are the standard rates of climb and descent for the cabin?
500fpm climb
300fpm descent
How does Boeing logic climb or descend the cabin?
Approximately relative to the rate of climb or descent of the cabin
On take off, what is the max cabin differential pressure?
0.125psi (approx 200 feet)
What happens to the outflow valve as the Thrust levers are advanced?
Starts to close, cabin begins descent to max of 0.125
Where does the cabin start to maintain 8.6psi?
FL350
At less than FL350 where would you expect to see the cabin PSI?
Less than 8.6
Above FL350 what cabin altitude would you expect to see?
8.6psi maintained relative to the aircraft altitude
Where does the pressurisation controller get inputs from?
Thrust levers
ADC
Landing Field Elevation
Captains Altimeter
Air/Ground Logic Main wheels
For a flight originating from a high altitude airport (>approx 4000’) what altitude would you see for the cabin altitude?
Take off airport altitude?
What are the 3 phases of flight that the cabin pressurisation recognises?
Climb
Cruise
Dsecent
How does the cabin transition from climb to cruise phase?
Level off for more than 1 minute
How does the cabin transition from cruise to climb?
Change of altitude >1000 feet
What does the cabin pressurisation consider upon entering cruise?
Cabin altitude and final landing altitude comparison
Selects higher of the 2
How does the cabin enter descent phase from cruise?
Descent of more than 1000 feet
Maintains 8.6 psi until FL350 then descends at Boeing logic
With an RTO what happens to the outflow valve?
Automatically opens fully
If the cabin reaches 11,000 feet what happens to the outflow valve?
Boeing logic uses the DC power to close the outflow valve
Uses different system to sense cabin altitude in this situation
Called Cabin Rate limiting
What happens at 14,000 feet?
Deploys the oxygen masks automatically
How long does the oxygen generation system last?
12 minutes
When does the cabin altitude warning system message display on the EICAS?
10,000
‘Resets at 8,500
On standby power, who controls the pressurisation?
Manual control
When does the pressurisation auto INOP light come on?
AUTO 1 and 2 fail
Select manual, in flight, with all systems powered
With failure of AUTO 2 what happens with Boeing logic?
Automatically swaps between AUTO 2 and 1, but with no indication or light
When both auto controllers fail, where does the outflow valve go?
Freezes in the the position it was in when the failure occurred.
Stays in that position until manual control is established
Placing the mode selector in Manual what happens?
Power removed from both AUTO controllers
Where are the pressure relief valves located?
FWD of the left wing root, just above wing
When do the Positive pressure relief valves open?
> 9.1psi
The positive pressure relief valve doors open in flight, what happens to the doors?
They remain open. Reset by maintenance
When do the negative pressure relief doors open?
Px greater inside the aircraft than outside
How many negative pressure relief doors do we have?
5
2 Rear cargo doors have 2 negative pressure relief doors
Discreet cabin altitude light comes on when?
> 10,000 cabin altitude
Master Warning light and aural
Extinguishes when cabin descends below 8500
With a failure of AC power, what happens to the outflow valve?
Freezes in position until Manual power is established
What has to happen for the AUTO INOP light to turn on inflight?
Manual Mode Select
