US20110148192A1 - Aircraft security system - Google Patents

Abstract

The security system provides an aircraft security system capable of protecting both single and multiple engine aircraft. Variations of the present system prevent unauthorized starting of protected aircraft and activate an alarm when engine starting it is attempted. Embodiments of the system draw no power from the aircraft when the security system is armed and in no way interferes with the normal starting or operation of the aircraft when the system is disarmed. Embodiments of the present system can activate an alarm when an aircraft's doors or panels are opened. Embodiments of the present invention can activate an alarm when installed equipment or other devices are tampered with or removed from their housings.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)
• This application is a continuation of U.S. patent application Ser. No. 12/197,538, filed Aug. 25, 2008, which is a continuation of U.S. Pat. No. 7,423,554, Ser. No. 11/138,652, filed May 26, 2005, which application claims the benefit under 35 U.S.C. 119(e) from U.S. Provisional Application Ser. No. 60/576,262, filed Jun. 2, 2004, which are incorporated herein by reference in their entirety.
FIELD OF INVENTION
• This application relates generally to methods and apparatus for an aircraft security and alarm system.
BACKGROUND
• The physical security of aircraft is historically poor on most aircraft in operation today. Aside from the ignition switches, the only security provided on most aircraft is key-type door locks which are generally of poor quality and can be readily opened with a wide variety of keys. Once inside the aircraft, an intruder has easy access to a multitude of easily removable and often expensive avionics and instrumentation devices. Engine ignition is also easily accomplished by an unauthorized person. For example, most single engine aircraft have key-type, turn-to-start ignition switches. The switch units are readily accessible and clearly marked on the back as to the function of each terminal, making the switch units easily bypassed and/or hot wired to achieve ignition. Multi-engine aircraft have no start security in that they have only toggle and/or push-button ignition switches.
• Accordingly, there is a need for an aircraft security system that is simple, light-weight, easy to install in new and existing aircraft, and is difficult to detect by an unauthorized person—yet prevents operation of the aircraft when armed. In addition, there is a need for a security system that does not draw power from the aircraft when armed, and is functional only when the aircraft is on the ground and parked.
SUMMARY
• The various embodiments described herein relate to methods and apparatus of an aircraft security system. The teachings provided herein solve the earlier mentioned problems and additional problems not stated herein.
• _write
• This summary is an overview of some of the teachings of the present application and is not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description below and in the appended claims. Other aspects of the system will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which are not to be taken in a limiting sense. The scope of the present system is defined by the appended claims and their legal equivalents.
BRIEF DESCRIPTION OF THE FIGURES
• FIG. 1A illustrates a block diagram of one embodiment of the present Aircraft Security System configured for both single and multi engine aircraft.
• FIG. 1B illustrates a block diagram of one embodiment of the present Aircraft Security System configured for both single and multi engine aircraft.
• FIG. 2 illustrates a schematic view of one embodiment of the present Aircraft Security System configured for single engine aircraft.
• FIG. 3 illustrates a schematic view of one embodiment of the present Aircraft Security System configured for multi engine aircraft.
• FIG. 4 illustrates a schematic view of one embodiment of the present Aircraft Security System configured for single engine aircraft.
• FIG. 5 illustrates a schematic view of one embodiment of the present Aircraft Security System configured for multi engine aircraft.
DETAILED DESCRIPTION
• In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments. It will be apparent, however, to one skilled in the art that the various embodiments may be practiced without some of these specific details. The following description and drawings provide examples for illustration, but are not intended in a limiting sense and are not intended to provide an exhaustive treatment of all possible implementations.
• It should be noted that references to “an embodiment” or “one embodiment” in this disclosure are not necessarily to the same embodiment, and such references may contemplate more than one embodiment. Further, the terms “bus” and “buss” are used interchangeably throughout the specification and in the drawings.
• Further, references made to actuation of a switch may include opening or closing of a switch. It is understood that embodiments demonstrating a circuit having a switch in a first state may also be reconfigured to a circuit having a switch in a second state without departing from the scope of the present subject matter. Thus, an embodiment having a normally closed switch may be realized in an embodiment having a normally open switch without departing from the present subject matter. Those of skill in the art upon reading and understanding the present application will appreciate that differences in configuration and components may be employed without departing from the scope of the present teachings.
• FIG. 1A illustrates a block diagram of one embodiment of anaircraft security system100, includingblock71 including an aircraft battery,block72 including an aircraft master switch and an electrical buss,block73 including an anti-theft system,block74 including one or more aircraft starter switches for single and multiple engines, andblock75 including one or more aircraft starter relays and starter motors for single and multiple engines.FIG. 1A illustratesblocks71,72,73,74, and75 as being coupled byconnections80,81,82, and83 all being shown as a single line. However, it will be realized by those of ordinary skill in the art thatconnections80,81,82, and83 may include one or more conductors and one or more other forms of electrical or mechanical couplings betweenblocks71,72,73,74, and75 without departing from the scope of the present subject matter.
• In one embodiment, the aircraft battery ofblock71 couples throughconnection80 to the aircraft master switch and electrical buss ofblock72. In one embodiment, the aircraft master switch ofblock72, when closed, allows power from the aircraft battery to reach the electrical buss ofblock72, and when the aircraft master switch is open, power from the aircraft battery is disconnected from the electrical buss. When the master switch is closed, power from the electrical buss ofblock72 is coupled throughconnection81 to the anti-theft system ofblock73. In one embodiment, the anti-theft system operates in both an activated or armed mode, and a deactivated or unarmed mode. The apparatus and methods for determining the modes and operations of the anti-theft system are described in further detail below.
• If power fromblock72 reachesblock73 and the anti-theft system is activated, the anti-theft system will disconnect the power supplied fromblock72, and thus not allow power for the aircraft battery topower block74 orblock75. By not allowing power to reachblocks74 and75, the anti-theft system ofblock73 prevents the starting of the engine or engines present on the aircraft, even if the aircraft starter switch or switches ofblock74, as described below, are actuated (closed).
• If power fromblock72 reachesblock73 and the anti-theft system is deactivated, the anti-theft system will allow the power to be coupled throughconnection82 to block74. In various embodiments,block74 includes one aircraft starter switch, associated with the singe engine of a single engine aircraft. If power is supplied toblock74 and the aircraft starter switch is actuated (closed), power will be coupled throughconnection83 toblock75. In various embodiments,block75 includes an aircraft starter relay that will be energized by the power supplied throughconnection83. When energized, the aircraft starter relay will allow power to reach the starter motor associated with the aircraft engine, and thus allow starting of the aircraft's engine.
• In various embodiments,block74 includes multiple aircraft starter switches, wherein each of the switches is associated with one of the engines of a multiple engine aircraft. If power is supplied toblock74 and one of the aircraft starter switches ofblock74 is actuated (closed), power will be coupled throughconnection83 toblock75. It will be realized by those of ordinary skill in the art that for multiple engine applications,connection83 may include separate connections associated with each of the engines of the multiple engine aircraft. In various embodiments, block75 includes multiple aircraft starter relays, each one being associated with a starter motor. When power is supplied to block75 throughconnection83, the particular starter relay associated with the starter switch being actuated will be energized. When energized, the particular starter relay energized will allow power to reach the aircraft starter motor associated with that starter relay, allowing the aircraft engine associated with that starter motor to be started.
• As described above with regards to a single engine aircraft, for a multiple engine aircraft, if power fromblock72 reaches block73 and the anti-theft system is activated, the anti-theft system will disconnect the power supplied fromblock72, and thus not allow power from the aircraft battery ofblock71 topower block74 orblock75. By not allowing power to reachblocks74 and75, the anti-theft system prevents starting of the engines present on the aircraft, even if the aircraft starter switch of the one or more starter switches ofblock74 are actuated (closed). Thus, when activated, the anti-theft system prevents starting for any of the engines on the multiple engine aircraft.
• FIG. 1B illustrates a block diagram of one embodiment of anaircraft security system110. The embodiment ofaircraft security system110 is similar to the embodiment ofsystem100, except that block74 (aircraft starter switch -single and multiple engine) is coupled to block72 throughconnection81, and block74 is further coupled to the anti-theft system ofblock73 throughconnection82. The anti-theft system ofblock73 is coupled to block75 throughconnection83.System110 functions in a similar manner tosystem100. However, one embodiment may be preferred over the other with regards to installment of the system on an aircraft due to, among other factors, physical access to the various portions of the circuits in the aircraft.
• FIG. 2 illustrates one embodiment of anaircraft security system200 including a starter breaker4 electrically connected tomain power bus3 and astarter switch5, where themain power bus3 is powered by amaster switch2 from amain battery1. In various embodiments,main power bus3 may be an instrument bus.System200 further includes asecurity relay11 having activation means for a first set ofcontacts20 and a second set ofcontacts21, where the first set ofcontacts20 are normally closed, and are electrically connected to astarter switch5, astarter relay6, and where the second set ofcontacts21 are normally open and are electrically connected to aremote battery14, aremote switch12, analarm13, and adiode10A. Asecurity switch9 is electrically connected to thesecurity relay11. In one embodiment,security switch9 is a key lock switch. Other embodiments having different types of switches are possible without departing from the scope of the present subject matter.
• System200 includes one or more modes of operation. In normal, unarmed operation,security switch9 is open, and the control coil ofsecurity relay11 is de-energized. In this mode, normally closedcontacts20 ofsecurity relay11 will be in a closed state. Activation of themaster switch2 and thestarter switch5 in this mode causes current to flow through the normally closedcontacts20 of thesecurity relay11, allowing current flow frommain power bus3 and starter breaker4, to thestarter relay6, which, when energized, closescontacts22 ofstarter relay6. Withcontacts22 closed, power is delivered tostarter motor7 fromstarter bus23 throughelectrical connection55,contacts22, andelectrical connection56.
• In another mode of operation ofsystem200,security switch9 is closed. The control coil ofsecurity relay11 is electrically coupled tomain power bus3 throughelectrical connection60,security switch9,electrical connection57. In one embodiment,diode10B coupleselectrical connection60 withelectrical connection59,electrical connection59 being coupled tosecurity switch9. Activation ofmaster switch2 with a closed (armed)security switch9 allows current frommain battery1 to flow throughmaster switch2 to themain power bus3, and thus energizes the control coil ofsecurity relay11, causing normally closedcontacts20 to open. With normally closedcontacts20 open, the current flow from themain power bus3 tostarter relay6 is disconnected.Starter relay6 remains de-energized, andcontacts22 remain open. Withcontacts22 open, no power is delivered tostarter motor7 from thestarter bus23. With normally closedcontacts20 open, activation ofstarter switch5 will not allow power frommain battery1 to energizestarter relay6, and thus will prevent starting of the aircraft.
• FIG. 2 illustrates an embodiment of thesecurity system200 in which at least one application is configured for single engine aircraft. During normal operation, themaster switch2 is closed, allowing battery power from themain battery1 to flow to themain power bus3 throughelectrical connections50 and51. During a normal ignition sequence, current flows from themain power bus3 throughelectrical connection67 to starter breaker4, then throughelectrical connection52 tostarter switch5. Whenstarter switch5 is actuated (closed), current flows throughstarter switch5, and throughelectrical connection58 to the normally closedcontacts20 of thesecurity relay11. From normally closedcontacts20, current flows throughelectrical connection54, energizing the control coil ofstarter relay6, andclosing contacts22, providing power to theengine starter motor7 fromstarter bus23 throughelectrical connection55,contacts22, andelectrical connection56.
• In various embodiments, thesecurity switch9 includes, but is not limited to, a toggle switch, a key pad, or a biometric security device which is activated for proper operation of the aircraft. In various embodiments, activation may include entering a Personal Identification Number (PIN) on a key pad before proper operation of the aircraft will be enabled. In various embodiments, the function and location of thesecurity switch9 is known only to authorized operators of the aircraft. In one or more embodiments, when the owner/operator desires security, the normallyopen security switch9 is closed. Oncesecurity switch9 is closed, activating themaster switch2 causes current to flow from themain power bus3 alongelectrical connection57 to the now closed (armed) contacts of thesecurity switch9. Power is now available, throughelectrical connection60, to the control coil ofsecurity relay11, activatingsecurity relay11. In various embodiments, the path of current flow includeselectrical connection59 anddiode10B.
• Activation ofsecurity relay11 causes various events to occur. In an embodiment, the energizedsecurity relay11 opens the normally closedcontacts20, thus opening the start circuit and preventingstarter motor7 from energizing, even whenstarter switch5 is actuated, or ifstarter switch5 is tampered with. For example even if the “S” and “B” terminals ofstarter switch5, as illustrated inFIG. 2, are jumpered or otherwise shorted, the normallyopen contacts20 will prevent power from being delivered tostarter relay6, and thus prevent starting of the aircraft's engine.
• In various embodiments, the energization ofsecurity relay11 will close normallyopen contacts21. With normallyopen contacts21 closed, current can flow fromremote battery14 throughelectrical connection61 and throughremote switch12 and throughelectrical connection62, and through the now closed normallyopen contacts21 of thesecurity relay11. Current then continues to flow throughelectrical connection63 anddiode10A toelectrical connection60, providing a second source of current flow through the control coil ofsecurity relay11, keepingsecurity relay11 energized (latched). In various embodiments, the current flow toelectrical connection63 will allowalarm13 to become activated. Once latched,security relay11 andalarm13 will remain activated even if starter breaker4 is opened or if the aircraft's primary power is removed from themain power bus3 by opening the aircraft'smaster switch2.Alarm13 is deactivated by opening the contacts ofremote switch12. In various embodiments, the function and location of theremote switch12 is known only to the owner/operator of the aircraft or other authorized persons.
• FIG. 3 illustrates an embodiment where thesecurity system300 is useful in applications, including, but not limited to, use in multiple engine aircrafts. Reference numbers are repeated for elements ofFIG. 3 which are the same or similar to those ofFIG. 2. Elements inFIG. 3 depicting additional iterations of the same or similar elements as depicted inFIG. 2 are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.” According to various embodiments ofsystem300, during normal operation,master switch2 is activated allowing battery power to flow frommain battery1 tomain power bus3. During a normal ignition sequence, current flows frommain power bus3 throughelectrical connection67 and starter breaker4, then throughelectrical connection52 to the normally closedcontacts20 ofsecurity relay11. In various embodiments, the current continues to flow throughelectrical connections53A and53B to the normally open contacts of the engine starter switches5A and5B respectively. In various embodiments, current also flows to additional engine starting circuits, for example,electrical connections53C and53D to the normally open contacts ofstarter switches5C and5D respectively. For purposes of illustration, only the complete starting circuits associated withstarter switches5A and5B are shown and further discussed in detail. However, it will be recognized by those skilled in the art that similar iterations of these circuits could be duplicated without departing from the scope of the present subject matter.
• In one embodiment, starter switches5A and5B are operated by separate means. In one embodiment, starter switches5A and5B may be operated at separate times. Whenstarter switch5A is activated, current flows through its closed contacts andelectrical connection54A to the associatedstarter relay6A, energizing the control coil ofstarter relay6A, andclosing contacts22A. Withcontacts22A closed, current fromstarter bus23A flows throughelectrical connection55A,contacts22A, andelectrical connection56A topower starter motor7A. Thus, the starting of the aircraft's engine associated withstarter motor7A is enabled.
• When thestarter switch5B is activated, current flows through its closed contacts andelectrical connection54B to the associatedengine starter relay6B, energizing the control coil ofstarter relay6B, andclosing contacts22B. Withcontacts22B closed, current fromstarter bus23B flows throughelectrical connection55B,contacts22B, andelectrical connection56B to power starter motor7B. Thus, the starting of the aircraft's engine associated with starter motor7B is enabled.
• As discussed above, various embodiments ofsecurity system300 include additionalelectrical connections53C and53D that are coupled tostarter switches5C and5D respectively. These additional circuits and starter switches are coupled to additional starter relays (not shown) and starter motors (not shown). It will be realized by those of skill in the art that additional circuits and various combinations of starter switches are possible without departing from the scope of the present subject matter.
• In various embodiments, the function and location of thesecurity switch9 is known only to authorized operators of the aircraft. When the owner/operator desires security,security switch9 is activated (closed). In an embodiment, whensecurity switch9 is activated and an unauthorized start is attempted, current flows frommain power bus3, throughelectrical connection57 and the now closedsecurity switch9, throughelectrical connection60, and to the control coil ofsecurity relay11, thus activatingsecurity relay11. In one embodiment,electrical connection60 is coupled tosecurity switch9 throughelectrical connection59 anddiode10B.
• Whensecurity relay11 is activated, various events occur. In an embodiment, the normally closedcontacts20 of thesecurity relay11 open, removing power from the starter switches5A and5B, and preventing either of the engines from being started, even if starter switches5A or5B are actuated. In an embodiment, whensecurity relay11 is activated, the normallyopen contacts21 ofsecurity relay11 close, allowing power to flow from theremote battery14 through theremote switch12 andelectrical connections61, and62, through the now closed contacts of normallyopen contacts21, and throughelectrical connection63 to theaudio alarm13. Current also flows fromelectrical connection63 throughdiode10A to keep thesecurity relay11 activated (latched) even if the starter breaker4 is reopened or when the aircraft's primary power is removed from themain power bus3 by re-opening the aircraft'smaster switch2. In one embodiment, oncesecurity switch9 is opened (unarmed), theaudible alarm13 is turned off by openingremote switch12. This removes power from thealarm13 as well as from the control coil of thesecurity relay11, unlatchingsecurity relay11. Unlatchingsecurity relay11 causes normallyopen contacts21 to open, and normally closedcontacts20 to close.
• FIG. 4 illustrates an embodiment of thesecurity system400 enhanced to provide security against unauthorized entry and unauthorized removal of installed devices. The embodiment is shown for single engine aircraft, but is equally applicable to multi-engine aircraft as shown inFIG. 5. Reference numbers are repeated for elements ofFIG. 4 that are the same or similar to those ofFIG. 2. Elements inFIG. 5 depicting additional iterations of the same or similar elements as depicted inFIG. 4 are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.”
• Various embodiments ofsecurity system400 are enhanced to includesecurity switch9 coupled tomain power bus3 throughelectrical connection57 and a circuit protection device, for example, an in-line fuse26, is included betweenelectrical connections57 and58.Electrical connection58couples circuit24 ofsecurity switch9 throughdiode10B toelectrical connection60, which then is coupled to the coil (the control portion) ofsecurity relay11. Whensecurity switch9 is closed (armed) andmaster switch2 is activated, power frommain battery1 flows frommain battery1 throughmaster switch2 andmain power bus3, and further throughcircuit24 ofsecurity switch9 to energize the coil ofsecurity relay11.
• Once activated,security relay11 opens normally closedcontacts20 and closes normallyopen contacts21, latchingsecurity relay11 throughremote battery14 andremote switch12 while preventing the powering ofstarter relay6, as described above. Further, in various embodiments,alarm13 is activated whensecurity relay11 is energized.
• As illustrated inFIG. 4, in various embodiments ofsystem400, aircraft doors and removable equipment are protected withswitches15 and16. InFIG. 4, switches15 and16 are shown as magnetic switches. However, switches15 and16 are not limited to being magnetic switches. In one embodiment, switches15 and16 are motion activated. In an embodiment, switches15 and16 are proximity switches. In various embodiments, other type switches are possible, including, but not limited to, optical, Hall effect, pressure, or other types of switches, such as proximity or motion activated switches. In various embodiments, additional switches are included. In various embodiments, switches15 and16 will not be the same type of switch. It will be recognized that various type switches, and various combinations of types of switches, may be used in a variety of applications and in various combinations. In various embodiments, switches15 and16 are in communication withsystem400 using a wireless form of coupling.
• In various embodiments, switches15 and16 are arranged so that when a door or a hatch of the aircraft is opened, or in the case of installed equipment, the equipment is tampered with or removed from its housing, the associatedswitch15 or16 is actuated. This allows current to flow fromremote battery14 throughelectrical connection61 andremote switch12, on throughelectrical connection64 and the now actuated contacts ofswitches15 or16, then on throughelectrical connection65 to thecircuit25 of thesecurity switch9. If the security system is set on (armed), thecircuit25 ofsecurity switch9 will be closed, allowing current to flow throughelectrical connection66 anddiode10C to activate and latchsecurity relay11, as discussed above. In various embodiments,alarm13 is also activated whensecurity relay11 is activated or latched. In various embodiments,alarm13 includes an audible alarm. In various embodiments, the alarm is a silent alarm. In various embodiments,alarm13 includes notification of the activation of the alarm to one or more various parties, including but not limited to, the aircraft owner, the aircraft operator, airport security officials, and law enforcement officials.
• In one embodiment, activation ofsecurity relay11 will cause normally closedcontacts20 to open, and thus prevent starting of the engine associated withstarter motor7, even ifstarter switch5 is tampered with as discussed above. In an embodiment,alarm13 is turned off by openingremote switch12 as discussed above.
• FIG. 5 illustrates an embodiment where thesecurity system500 is useful in applications, including, but not limited to, use in multiple engine aircrafts. Reference numbers are repeated for elements ofFIG. 5 which are the same or similar to those ofFIG. 4. Elements inFIG. 5 depicting additional iterations of the same or similar elements as depicted inFIG. 4 are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.”
• As illustrated inFIG. 5, in various embodiments ofsystem500, aircraft doors and removable equipment are protected withswitches15 and16. In various embodiments, switches15 and16 are arranged so that when the door or hatch of the aircraft is opened, or in the case of installed equipment, the equipment is tampered with or removed from its housing, the associatedswitch15 or16 is actuated. In various embodiments, switches15 and16 are in communication with thesystem500 through a wireless coupling. In various embodiments, if either ofswitches15 or16 actuate whensecurity switch9 is activated (armed),security relay11 will be energized, and normally closedcontacts20 will open. With normally closedcontacts20 open, power is disconnected fromstarter switches5A and5B, and thus activation of either ofstarter switches5A or5B, even if tampered with or bypassed, will not enable the starting of either of the aircraft's engines associated withstarter relays6A and6B. In various embodiments, if provided, additional engine starting circuits, for example, circuits associated withstarter switches5C and5D (associated starter relays and starter motors not shown), would also be disconnected from power, and thus would also disable the starting of the aircraft's engine associated with that circuit.
• In various embodiments ofsystem500, activation ofsecurity relay11 will latchrelay11. In various embodiments,alarm13 is also activated whensecurity relay11 is activated or latched. In an embodiment,alarm13 is turned off by openingremote switch12 as discussed above.
• This description has set forth numerous characteristics and advantages of various embodiments and details of structure and function of an aircraft security system, but is intended to be illustrative and not intended in an exclusive or exhaustive sense. Changes in detail, material and management of parts, order of process and design may occur without departing from the scope of the appended claims and their legal equivalents.

Claims (22)

1. A system for securing an aircraft having a starter, a starter switch, and a master switch to connect, in an on position, a first power source to a main power bus, the system comprising:

a security system connected to control power to the starter, the security system including:

a security switch adapted to arm the security system in an armed state and to disarm the security system in a disarmed state;

a second power source to provide backup power to the security system;

a controllable switch adapted to complete a starter circuit for powering the starter in a first mode and to break the starter circuit in a second mode, the controllable switch adapted to be controlled by sensing states of at least the security switch and the main power bus,

and wherein in the armed state the security system is configured to prevent activation of the starter upon detection of attempted use of the aircraft before disarming the security system.

2. The system ofclaim 1, wherein attempted use of the aircraft before disarming the security system includes the master switch being in the on position.

3. The system ofclaim 1, wherein the second power source is connected to the controllable switch and is adapted to maintain the controllable switch in the second mode once the controllable switch has entered the second mode.

4. The system ofclaim 1, further including a remote switch to reset the security system when the security system is activated.

5. The system ofclaim 1, further including the controllable switch being adapted to be controlled by sensing states of one or more switches connected to the second power source.

6. The system ofclaim 5, wherein one or more switches connected to the second power source includes a switch associated with a door of the aircraft.

7. The system ofclaim 5, wherein one or more switches connected to the second power source includes a switch associated with an installed device of the aircraft.

8. The system ofclaim 1, further including an alarm coupled to the security system.

9. The system ofclaim 1, wherein the second power source is coupled to the alarm and is adapted to power the alarm until disconnected using a remote switch to reset the security system once the security system is activated.

10. The system ofclaim 1, wherein in the armed state the security system is configured to prevent activation of a second starter upon detection of attempted use of the aircraft before disarming the security system.

11. An aircraft electrical system comprising:

a master switch connected to a battery;

a starter relay having a starter switch interconnecting the main switch to the starter relay;

a security switch connected to the main switch; and

a security relay having a coil connected to the security switch;

wherein the security relay interconnects the main switch and the starter relay in a coil unpowered state of operation, and further disconnects the main switch and the starter relay and interconnects a remote battery and the coil in a coil powered state of operation.

12. The system ofclaim 11, wherein a normally closed set of contacts of the security relay interconnects the main switch and the starter relay in the coil unpowered state of operation.

13. The system ofclaim 11, wherein a normally open set of contacts of the security relay interconnects the remote battery and the coil in the coil powered state of operation.

14. The system ofclaim 13, wherein a remote switch interconnects the remote battery and the normally open set of contacts of the security relay.

15. The system ofclaim 11, further including an alarm, wherein the alarm interconnects to the remote battery in the coil powered state of operation.

16. The system ofclaim 11, further including a switch, wherein the switch interconnects the remote battery through the security switch to the coil.

17. The system ofclaim 16, wherein the switch is adapted to interconnect the remote battery through the security switch to the coil when a door associated with the switch is opened.

18. The system ofclaim 16, wherein the switch is adapted to interconnect the remote battery through the security switch to the coil when an installed device associated with the switch is removed.

19. The system ofclaim 11, wherein the security relay interconnects the main switch and a plurality of starter relays in the coil unpowered state of operation.

20. An apparatus for securing an aircraft, comprising:

a first power supply;

a starter and starter relay for use in starting an engine of the aircraft;

a main power bus and master switch providing power to the starter relay and starter; and

switch means for controllably disconnecting the first power supply from the starter relay and starter upon detection of an attempted intrusion while in an armed state.

21. The apparatus ofclaim 20, further comprising alarm means.

22. The apparatus ofclaim 20, further comprising a second starter and a second starter relay for use in starting a second engine of the aircraft.

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