PS1’s pneumatics simulation incorporates the entire bleed air ducting of the 747, pressurized -- as desired -- by the various bleed air supplies (APU, or ground source, or the engines). PS1 models the control logic of the valves, the associated cockpit panels and indications, as well as a number of malfunctions such as bleed air overheat, bleed duct leak, cabin depressurization, cabin pressure controller fault, equipment cooling failure, pack system fault and overheat, smoke in air conditioning etc. Certain bleed air related malfunctions may affect other aircraft systems as well. The following systems operate with bleed air:
- Aft cargo heat
- Air conditioning and cabin pressurization (packs)
- Air driven hydraulic demand pumps
- Hydraulic reservoir pressurization
- Engine starter motors
- Leading edge flaps
- Potable water pressurization
- Smoke detection
- Thrust reverser mechanism (on CF6 and RB211 only)
- Wing and nacelle anti-ice

The simulation reflects the automatic control of the ouflow valves: The cabin altitude falls 100 feet below the airport altitude during the take-off roll, then rises along a particular altitude profile, ending again at 100 feet below field elevation upon touch-down, and rising to field elevation during the roll-out.

Limitations in version 1.3: The “manual” control of the outflow valves and cabin zone temperatures is not modelled. Modelled is only the “automatic” control system of the outflow valves and temps.

Sample screen shots: Pneumatics Simulation

ABOVE: All switches and lights displayed on the overhead panel are fully functioning in Precision Simulator. The EICAS synoptic (lower right corner) reacts to manual and automatic system inputs, and accordingly indicates the present status of the pneumatics system.

ABOVE: Although the APU is running, bleed air is not available as the APU Bleed Air Valve has been cut off by the pilot.

LEFT: The APU Bleed Air Valve has been turned on. The left and right duct pressure is now at 23 psi.

RIGHT: The APU is shut down. The APU Bleed Air Valve is turned off by the system logic (see EICAS valve symbol). A ground bleed air supply is now connected to the aircraft.
(Note: The Gasper and Humid Switches are airline options.)

ABOVE: Engine #1 has got a bleed air overheat. Although the valve has closed automatically, the pilot’s supposed to turn off the associated Engine Bleed Air Switch. Nacelle anti-ice #1 is no longer available. As the above 747 is fitted with CF6 engines, the #1 thrust reverser is now inoperative.

RIGHT: This is a malfunction in pack #3. This can now be a pack overheat or a pack controller fault. The exact problem in this malfunction simulation is random controlled. The pilot can now handle this situation using the “Abnormal (Check-)Lists” which are included in the PS1 package as well.

LEFT: Another malfunction -- a leak in the left bleed air duct. Among other things, the pilot now has to turn off the left Isolation Valve in order to isolate the center and right duct. Several systems are now inoperative, e.g. the hydraulic demand pump 1 (in some airlines also demand pump #2).

ABOVE: This is an emergency scenario -- a rapid cabin depressurization. The cabin altitude read-out on the EICAS indicates more than 36000 feet and is still rapidly rising. The pilot just initiated an emergency descent from FL430.

What do other aviation professionals say about this simulator?

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