User manual

Page 83
Aircraft Operation Manual
Piper Cheyenne I, IA, II, IIXL
For ight simulation use only
heater ducts, and through the cool air ducts along both sides of the cabin to in-
dividually controlled air outlets. When the control is in the OUTSIDE AIR position,
the air is not needed for pressurization. Air is then routed below the cabin oor
and overboard. During ground operations, to prevent fumes from other aircraft
entering the cabin, the control may be placed in the RECIRCULATED AIR position.
In this position, no outside air enters the system. Restrict continuous operation in
the recirculated air position to 15 minutes.
Before takeoff, set cabin altitude 500 feet above the eld pressure altitude, using
the cabin altitude controller (4). Cabin pressurization will begin as the cabin pas-
ses through the altitude selected. Cabin altitude will remain at the selected alti-
tude until maximum cabin differential (5.5 PSI) is reached, at which time the cabin
altitude will begin to climb, until at 29.000 feet (IIXL only: 31.000 feet) pressure
altitude the cabin pressure altitude will be 10.000 feet (Garret: 11.100 feet). For
ights below an airplane altitude of 13.000 feet (Garret: 12.000 feet), the cabin
altitude control (4) should be left at the takeoff setting. For ights above 13.000
feet (Garret: 12.000 feet) (at which point maximum differential will be exceeded)
set the cabin altitude controller (4) to the cruise altitude +500 feet and adjust the
cabin rate of climb (1) as desired. It is recommended that this setting be made
during climb out after the controller has captured isobaric control.
To descend for landing be certain that the selected cabin altitude is higher than
the pressure altitude of the landing eld. Shortly after descent is initiated, set
the cabin altitude controller (4) to 500 feet above the pressure altitude of the
landing eld and adjust the rate control (3) high enough to allow the cabin to
descend to the landing setting before the aircraft descends to that altitude. For
normal descent, the rate knob (3) should be at the twelve o’clock position. A hig-
her setting should be selected for rapid descent, so that the aircraft altitude does
not catch up with the cabin altitude.
To the immediate left of the cabin altitude selector and rate of change controls
are instruments to simplify setting the system and to monitor system operation.
The cabin altitude instrument (2) indicates the cabin altitude in feet, and the
cabin rate of change gauge (1) indicates the rate at which cabin altitude is chan-
ging in feet per minute. A differential pressure gauge, which is incorporated in
the face of the cabin altitude instrument (2), indicates the differential pressure
between the cabin and the outside atmosphere.