US 5,479,162 AGranted

Aircraft anti-theft system

AssigneeUnited Beechcraft, Inc.

InventorsRandall R. Barger, Thomas V. Saliga

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Abstract

An anti-theft system that can be retrofitted onto existing aircraft disables the starter motor of an engine or engines a predetermined time after the aircraft is taken out of service and re-enables starting only after the pilot has provided adequate identification (e.g. by entering a personal identification number at a cockpit keyboard). The predetermined time interval is selected to be long enough to ensure that the system does not impose a flight hazard by preventing in-flight re-starts. In a preferred version of the system, a drop in the output voltage of the aircraft's main electric power system is used as an indication that the aircraft is out of service. To simplify installation on existing aircraft, the system provides for communication among various functional elements over a pre-existing part of the aircraft (e.g. by imposing AC tones on a starter motor control line).

Claims8

Dependent claims

An anti-theft system installed on an aircraft comprising a pressurized cabin separated from other portions of the aircraft by a plurality of bulkheads, a main electric power system supplied by a starting battery or by a generator driven by an engine, and a starter control line having a first end connected to a start switch within the cabin and a second end connected to a starter relay located intermediate the cabin and the engine, the engine being startable by an electric starter motor powered by the main electric power system when the starter relay operates the starter motor, the system installed without penetrating any of the bulkheads, the system comprising:

operator-identification apparatus situated within the cabin, the operator-identification apparatus generating an input code, the operator-identification apparatus operatively connected to a first communication apparatus situated within the cabin and in turn operatively connected to the first end of the starter control line, and
a second communication apparatus connected to the second end of the starter control line, the second communication apparatus controlling a starter relay control apparatus having a first, locked, state in which the relay is prohibited from operating the starter motor, the starter relay control apparatus having a second, unlocked, state in which the relay operates the starter motor
wherein the first communication apparatus sends a first code signal, corresponding to the input code, as an alternating electric voltage on the starter control line, to the second communication apparatus, the second communication apparatus unlocking the starter relay control apparatus only if the first code signal matches an access code stored in the second communication apparatus.

Dependencies are inferred from the claim text.