Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
1999-06-22
2001-03-20
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C701S007000, C701S008000, C701S009000
Reexamination Certificate
active
06205376
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to aviation electronics (avionics). More particularly, the present invention relates to methods and apparatus for identifying blocked pitot tubes or static ports of the pitot-static system of an aircraft.
BACKGROUND OF THE INVENTION
Aircraft typically include pitot-static systems which are used to determine the longitudinal air speed and the altitude of the aircraft. The pitot system includes one or more pitot tubes which project out of the airframe, into the air stream, and allow the impact pressure of the atmosphere to enter the tube(s). Sensors sense a pressure differential to create an air speed indicative output. The pressure differential can be between the impact air pressure from the pitot tube and static air pressure from a static port. The air speed indicative output is provided, typically by an air data computer, to an air speed indicator in the cockpit.
The static system typically includes two or more of the static pressure ports which sense the atmospheric pressure outside of the aircraft, ideally without being influenced by pressure variances caused by movement of the aircraft. The standard atmospheric pressure sensed by the static ports is used to generate altitude indicative signals which are provided, typically by the air data computer, to an altimeter in the cockpit of the aircraft. Frequently, in newer aircraft, the static ports are integral to the pitot tubes.
The pitot tube(s) and static ports of a pitot-static system can sometimes develop blockages which seriously affect the accuracy of the sensed pressures, and therefore seriously affect the accuracy of the determined air speed and altitude. The pitot tubes and static ports can be blocked with foreign materials such as insects, birds, and ice, for example. In other instances, the static ports or pitot tube openings have been taped shut during maintenance of the aircraft, and accidentally left blocked. Erroneous air speed and altitude determinations made as a result of these blockages can create a dangerous operating situation for the aircraft.
SUMMARY OF THE INVENTION
Disclosed are avionics systems and methods of using the same to monitor a pitot-static system for blockages. A first aircraft movement rate is calculated as a function of a pressure sensed using the pitot-static system. A reference movement rate is calculated using an independent navigation system such as an inertial reference system, a global positioning system, or an attitude heading reference system. The calculated first aircraft movement rate is compared to the calculated reference movement rate to determine whether the calculated first aircraft movement rate falls within a predetermined tolerance range about the calculated reference movement rate. If the calculated first aircraft movement rate falls outside of the predetermined tolerance range about the calculated reference aircraft movement rate, it is determined that a blockage exists in at least one of a pitot tube or a static port of the pitot-static system.
REFERENCES:
patent: 4229725 (1980-10-01), Reilly
patent: 5349347 (1994-09-01), Muller
patent: 5938147 (1999-08-01), DoGroff
patent: 6038932 (2000-03-01), Wandel et al.
patent: 6101429 (2000-08-01), Sarma et al.
Cuchlinski Jr. William A.
Eppele Kyle
Jensen Nathan O.
Marc-Coleman Marthe Y.
O'Shaughnessy J. P.
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