Pilot’s Operating Handbook Section 7
EXTRA 500 Description of Airplane and Systems
warning light on annunciator panel if differential pressure is
above 5.65 psi or cabin altitude above 10,000 ft.
The cabin pressure control system is energized when the cabin
PRESS switch is in the ON position. In normal operation the
pressure controller (installed in the centre console) will govern
the cabin outflow so as to achieve a cabin altitude 700 ft above
the selected (on pressure controller dial) airport altitude. In case
changes in the selected cabin altitude are made by turning the
dial, the controller will not immediately change the cabin
outflow valve setting for the new cabin altitude selected but will
change this continuously until the new setting is reached to
avoid sudden cabin pressure changes. The rate of change
towards the new setting is adjusted with the rate control knob of
the cabin pressure controller. In the 12 o’clock position
approximately 500 ft/min cabin change rate are achieved.
Turning the knob clockwise results in higher rates of changes,
turning it counter clockwise results in lower rates of change.
In case the system is not energized (
PRESS switch OFF) the
outflow valve remains in the setting (selected cabin altitude) it
actually has.
The cabin outflow valve as well as the safety valve have an
additional mechanical setting for cabin pressure relief not
dependent on electric energy or function of the cabin pressure
controller. The pressure relief setting of the cabin outflow valve
is 5.6 psi, the safety valve opens at 5.7 psi.
The safety valve also provides the dump function. When
actuating the
DUMP switch the safety valve is electrically
actuated to open and allows rapid decompression of the cabin
e.g. in an emergency. The dump function is also activated by
the landing gear squat switch. This avoids inadvertent
pressurization of the plane in ground operation.
Note Landing with cabin differential pressure is prohibited
7.21.b Pressurization System Operation
Use the cabin pressure controller (
Figure 7-19) as follows and
refer to
Figure 7-18 sample chart:
1 Activate the pressurization controller by switching the PRESS
switch
ON.
26. January 2011 7-61
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