Air Conditioning And Pressurization / Oxygen Flashcards
What is normal and max pressure
differential
Normal 10.33 psi @FL420
( from cabin pressure chart )
Max. 10.73 psi
( AFM LIM and opening of
cabin safety valves )
note:
“CABIN DELTA P” msg. at 10.85 psi
The BMC’s extract bleed air
from which engine stages
5th stage low-pressure
8th stage high-pressure
note:
PRV limits the bleed pressure supply
to 43 +/- 3 psi
What occurs automatically when
a bleed leak is detected
The BMC isolates the effected manifold
by closing the appropriate valves
How is a Bleed leak depicted
on the synoptic page
Flow line is amber and
corresponding valves are closed
Can one engine supply two
AC packs simultaneously
No, The BMC prevents two packs
from being supplied by one engine
What happens when the system
has only one operating pack
High flow schedule is automatically
selected by the BMC
The HASOV’s close automatically
turning off the trim air
When do the packs automatically shut off ( FCV closed )
Bleed failure, shutdown
or engine starting
Ditching
( below 15,000’ )
Pack inlet overheat
Compressor discharge overheat
Pack discharge overheat
or under pressure
Selecting the TRIM AIR PBA switch
to OFF closes which valves
2 HASOV’s and trim air valves
What are the two modes of operation
with the cabin pressure control
system in AUTO
PRIMARY ( predictive ) uses FMS info
Autopilot on, VNAV engaged, and
Landing elevation source
selected to FMS
SECONDARY ( reactive ) uses airplane
altitude and vertical speed ( ADC )
What are the caution/warning
messages and associated cabin
altitudes during a loss of
pressurization
Amber "CABIN ALT" 8200' RED "CABIN ALT" 9000' note: when aircraft altitude goes below 41,000' with the landing elev. set to 7230' or higher the limits increase proportionately; caution at 1000' above landing field elev. warning at 1800' above landing field elev.
After selecting MAN pres. what
new info is displayed on
STATUS page
Both outflow valve position indicators
Cabin rate analog gauge
Cabin altitude and Delta P
note:
landing elevation is not displayed
( must monitor cabin alt )
How long does it take the cabin
pressure controller to remain
scheduled at the pre-pressurization
altitude after takeoff
10 minutes
What occurs when the EMER DEPRESS
switch is selected ON
Both outflow valves are
commanded open
Cabin altitude limited to 14,500’ +/- 500
What does selecting Ditching switch
ON provide
Air conditioning pack flow is shut off
Cabin is de-pressurized
OFV’s are driven to the closed position
note: inhibited above 15,000' manuall sequence; Packs Off, Emer Depress On, both OFV's closed
How many Oxygen bottles does the
system have
4