Air Conditioning And Pressurization / Oxygen Flashcards

1
Q

What is normal and max pressure

differential

A

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

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2
Q

The BMC’s extract bleed air

from which engine stages

A

5th stage low-pressure

8th stage high-pressure

note:
PRV limits the bleed pressure supply
to 43 +/- 3 psi

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3
Q

What occurs automatically when

a bleed leak is detected

A

The BMC isolates the effected manifold

by closing the appropriate valves

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4
Q

How is a Bleed leak depicted

on the synoptic page

A

Flow line is amber and

corresponding valves are closed

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5
Q

Can one engine supply two

AC packs simultaneously

A

No, The BMC prevents two packs

from being supplied by one engine

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6
Q

What happens when the system

has only one operating pack

A

High flow schedule is automatically
selected by the BMC

The HASOV’s close automatically
turning off the trim air

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7
Q
When do the packs automatically 
shut off ( FCV closed )
A

Bleed failure, shutdown
or engine starting

Ditching
( below 15,000’ )

Pack inlet overheat

Compressor discharge overheat

Pack discharge overheat
or under pressure

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8
Q

Selecting the TRIM AIR PBA switch

to OFF closes which valves

A

2 HASOV’s and trim air valves

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9
Q

What are the two modes of operation
with the cabin pressure control
system in AUTO

A

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 )

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10
Q

What are the caution/warning
messages and associated cabin
altitudes during a loss of
pressurization

A
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.
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11
Q

After selecting MAN pres. what
new info is displayed on
STATUS page

A

Both outflow valve position indicators

Cabin rate analog gauge

Cabin altitude and Delta P

note:
landing elevation is not displayed
( must monitor cabin alt )

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12
Q

How long does it take the cabin
pressure controller to remain
scheduled at the pre-pressurization
altitude after takeoff

A

10 minutes

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13
Q

What occurs when the EMER DEPRESS

switch is selected ON

A

Both outflow valves are
commanded open

Cabin altitude limited to 14,500’ +/- 500

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14
Q

What does selecting Ditching switch

ON provide

A

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
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15
Q

How many Oxygen bottles does the

system have

A

4

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16
Q

When do the pax masks automatically

deploy

A

14,500’ ( +500 / -750 )

17
Q

How is the crew alerted when
the oxygen bottle drops below
75% ( < 1,400 psi )

A

Amber
“OXYGEN LO QTY” CAS

Note:
this cas will also appear if the oxygen
cylinder SOV is closed

18
Q

What is the minimum oxygen quantity

for dispatch

A

75%