It is assumed that an automated valve controller changes exogenous clearance levels of inflow valve and outflow valve
. It tries to make a valve clearance level maximum if it is closed or vice versa if the valve is open.
It concluded it was a 'serious incident' and said the outflow valve
on the aircraft had also contributed to pressure problems on other aircraft.
To illustrate the model, let's take a simple example consisting of a fluid tank with an intake valve and an outflow valve
. An actors model of this system is illustrated in table 1 below.
Airborne troubleshooting revealed a stuck cabin-altitude gauge and a partially stuck open outflow valve
. These factors prevented the aircraft from maintaining the prescribed pressurization schedule.
Fluid tank actors model Tag Behaviors Controller Loop--continuous operation Intake Valve Intake open--allow fluid into the tank Intake close--stop flow of fluid into the tank Tank Check level--measure the level of fluid in the tank and request intake on reaching a minimum level or outflow when above a maximum level Outflow Valve
Ouflow open--allow fluid to exit the tank Outflow close--stop fluid exit from the tank Table 2.
If an outflow valve
that should be closed is accidentally left open, media can leak to the environment without notice or until another part of the control system discovers the error.
The Air Accident and Incident Investigation Board (AAIIB) of Cyprus could not conclusively determine the causes of the incident, but indicated two possibilities: an electrical malfunction causing the opening of the outflow valve
, or the inadvertent opening of the aft service door.Following the December 2004 incident, the airline had the plane thoroughly inspected (at the cost of some US$1 million) but no malfunctions were detected, according to Christos Neocleous, secretary of ajet.
The heating medium circulation is only active when the outflow valve
V5 opens towards the direction of the condenser and when the inflow valve AV2 is open.
Edmund Kim, M.D., of Lawrenceville, Ga., says to try closing the outflow valve
Each mechanical ventricle is essentially a polyurethane sac with an inflow and outflow valve
. The sacs are worked hydraulically: Hydraulic fluid is injected outside the sacs to compress them, and then drawn away to let them expand.
The Air Accident and Incident Investigation Board of Cyprus could not conclusively determine the causes of the incident, but indicated two possibilities: an electrical malfunction causing the opening of the outflow valve
, or the inadvertent opening of the aft service door.