Embraer EMB145 Operation Manual page 2108

PNEUMATICS
AIRPLANE
AIR CONDITIONING
OPERATIONS
AND PRESSURIZATION
MANUAL
AUTOMATIC PREPRESSURIZATION SEQUENCE ON GROUND
(NORMAL MODE OPERATION)
This sequence is initiated and maintained as long as the airplane is on
the ground and the engine 1 thrust lever is set to THRUST SET
position or above. It causes the cabin altitude to descend toward an
altitude equivalent to 0.2 psi (15 mbar) below the takeoff altitude.
The purpose of the automatic prepressurization is to avoid cabin
bumps due to the irregular airflow on the fuselage during rotation and
takeoff and also to keep a controlled cabin altitude just after rotation,
as the cabin altitude tends to follow the airplane altitude.
In the case of takeoff with air conditioning supply, the cabin altitude is
controlled with an altitude rate of descent equal to –450 ft/min.
In the case of takeoff without air conditioning supply, the outflow
valves are closed, also avoiding cabin bump.
TAKEOFF SEQUENCE
(NORMAL MODE OPERATION)
This sequence is initiated after the airplane leaves the ground with the
purpose of avoiding reselecting the landing altitude, in case it is
necessary to return to the takeoff airport.
It causes the cabin altitude to continue descending towards the
altitude equivalent to 0.2 psi below the takeoff altitude. If an altitude of
0.2 psi below the takeoff altitude has already been reached during the
prepressurization sequence, the cabin altitude does not change.
The takeoff sequence lasts until the theoretical cabin altitude becomes
greater than the actual cabin altitude, or until 15 minutes have elapsed
since the sequence initiation, whichever occurs first.
Page Code
5 02
2-14-15
REVISION 41
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