The Cabin pressure control system regulates the amount
of air that escapes the cabin through a pair of exit holes on the AFT
The Cabin pressure control system regulates the escape of air though the
use of two pneumatically driven outflow valves; the primary outflow valve
and secondary outflow valve’s are similar except for a pair of electric
solenoids (climb, dive) and an ejector package which is included only
on the primary outflow valve, in addition the primary outflow valve is
larger in diameter. The incoming air supply to the cabin is maintained
at a constant 10ibm/min (8imb/min single source) and is temperature controlled.
The pressure and rate of change of the cabin is determined by inputs from
the digital microprocessor (Also known as the Digital Altitude Controller),
Manual toggle valve and the cabin dump switch. The absolute cabin pressure
and the differential cabin pressure can be monitored in the cabin on the
cabin altitude gauge and on the differential gauge. The rate of cabin
change is seen in the rate window (lower) on the face of the Digital Altitude
Controller. The Digital Altitude Controller, the AUTO/Manual switch, the
Manual toggle valve, the cabin dump switch, the differential pressure
gauge, and cabin altitude gauge are all located on the cockpit tilt panel.
The primary outflow valve is located on the FWD inboard side of the AFT
pressure bulkhead and the secondary outflow valve is located on the FWD
outboard side of the AFT pressure bulkhead.