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&#39;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) 
       [0001]    This application is a continuation of U.S. patent application 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 
       [0002]    This application relates generally to methods and apparatus for an aircraft security and alarm system. 
       BACKGROUND 
       [0003]    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. 
         [0004]    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 
       [0005]    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. 
         [0006]    Various embodiments of the present system include a system for the protection of aircraft from unauthorized operation and use. Some embodiments of the present system are adapted to provide entry security, as well as security against unauthorized attempts to remove installed devices such as avionic instruments. The security system taught is simple, light-weight, and easy to install on single engine and multiple engine aircraft, both new and used. 
         [0007]    One or more embodiments of the security system includes a starter breaker electrically connected to a main power bus and a starter switch where the main power bus is powered by a master switch from a main battery. Embodiments of the system further include a security relay having a first set of contacts and a second set of contacts, where the first set of contacts are electrically connected to the starter switch, a starter relay, and a starter motor. The second set of contacts are electrically connected to a remote battery, an alarm, and an isolation diode. A keyed security switch is electrically connected to the security relay. 
         [0008]    A variety of modes of operation are described. In one mode of operation, and for certain embodiments, activation of the aircraft master switch with an open (non activated) security switch allows current to flow from the main power buss through the starter breaker and the normally closed contacts of the security relay to the starter switch. When the starter switch is closed, the starter relay is activated and current flows to the starter motor, hence starting the engine. 
         [0009]    Embodiments of the present invention include another mode of operation, where activation of the master switch with a closed (armed) security switch activates the security relay and transfers its contacts, preventing power from reaching the starter motor while also drawing current from a remote battery to energizing an alarm. In one or more embodiments, an alarm is continuously energized and the relay activated (latched) by current flowing from the remote battery back through the security relay contacts and an isolation diode to the relay coil, keeping it activated. In an embodiment, the alarm is deactivated and the security relay opened by momentary activation of a remote normally closed switch that, when opened, terminates current flow from the remote battery to the alarm and the security relay. 
         [0010]    Further embodiments of the system include, but are not limited to, implementation with solid state devices such as transistors, diodes and silicon controlled rectifiers. One or more embodiments of the present system relate to functional control of aircraft starting options, management of avionics, and control surface articulation. One or more embodiments include, but are not limited to, security switch arming and disarming alternatives including physical keys, coded key cards, microprocessors, remote fobs (transmitting over inferred, visible light, magnetic transfer, or radio frequencies) coded touch key pads, retina, face or finger print recognition, remote arming and disarming systems via telephone or cellular phone, and other radio frequency (RF) devices. 
         [0011]    One or more embodiments of the present system include, but are not limited to, alarm alternatives including various audible and/or visual alarms, silent alarms that would notify the owner or operator, and would notify law enforcement authorities or aircraft/airport controlling agencies. One or more embodiments of the present system include, but are not limited to, door and access entry and avionics security systems, including but not limited to, Hall effect switches, reed switches, optical switches, or other motion or pressure detection proximity switches. 
         [0012]    Various embodiments of the present system include a system for securing an aircraft having a starter, a starter switch, a master switch to connect a first power source to a main power bus in an on position, 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 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 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, 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. 
         [0013]    One or more embodiments of the present system include 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. 
         [0014]    Various embodiments of present system include 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 buss 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. 
         [0015]    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 
         [0016]      FIG. 1A  illustrates a block diagram of one embodiment of the present Aircraft Security System configured for both single and multi engine aircraft. 
           [0017]      FIG. 1B  illustrates a block diagram of one embodiment of the present Aircraft Security System configured for both single and multi engine aircraft. 
           [0018]      FIG. 2  illustrates a schematic view of one embodiment of the present Aircraft Security System configured for single engine aircraft. 
           [0019]      FIG. 3  illustrates a schematic view of one embodiment of the present Aircraft Security System configured for multi engine aircraft. 
           [0020]      FIG. 4  illustrates a schematic view of one embodiment of the present Aircraft Security System configured for single engine aircraft. 
           [0021]      FIG. 5  illustrates a schematic view of one embodiment of the present Aircraft Security System configured for multi engine aircraft. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    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. 
         [0023]    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. 
         [0024]    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. 
         [0025]      FIG. 1A  illustrates a block diagram of one embodiment of an aircraft security system  100 , including block  71  including an aircraft battery, block  72  including an aircraft master switch and an electrical buss, block  73  including an anti-theft system, block  74  including one or more aircraft starter switches for single and multiple engines, and block  75  including one or more aircraft starter relays and starter motors for single and multiple engines.  FIG. 1A  illustrates blocks  71 ,  72 ,  73 ,  74 , and  75  as being coupled by connections  80 ,  81 ,  82 , and  83  all being shown as a single line. However, it will be realized by those of ordinary skill in the art that connections  80 ,  81 ,  82 , and  83  may include one or more conductors and one or more other forms of electrical or mechanical couplings between blocks  71 ,  72 ,  73 ,  74 , and  75  without departing from the scope of the present subject matter. 
         [0026]    In one embodiment, the aircraft battery of block  71  couples through connection  80  to the aircraft master switch and electrical buss of block  72 . In one embodiment, the aircraft master switch of block  72 , when closed, allows power from the aircraft battery to reach the electrical buss of block  72 , 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 of block  72  is coupled through connection  81  to the anti-theft system of block  73 . 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 farther detail below. 
         [0027]    If power from block  72  reaches block  73  and the anti-theft system is activated, the anti-theft system will disconnect the power supplied from block  72 , and thus not allow power for the aircraft battery to power block  74  or block  75 . By not allowing power to reach blocks  74  and  75 , the anti-theft system of block  73  prevents the starting of the engine or engines present on the aircraft, even if the aircraft starter switch or switches of block  74 , as described below, are actuated (closed). 
         [0028]    If power from block  72  reaches block  73  and the anti-theft system is deactivated, the anti-theft system will allow the power to be coupled through connection  82  to block  74 . In various embodiments, block  74  includes one aircraft starter switch, associated with the singe engine of a single engine aircraft. If power is supplied to block  74  and the aircraft starter switch is actuated (closed), power will be coupled through connection  83  to block  75 . In various embodiments, block  75  includes an aircraft starter relay that will be energized by the power supplied through connection  83 . 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&#39;s engine. 
         [0029]    In various embodiments, block  74  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 to block  74  and one of the aircraft starter switches of block  74  is actuated (closed), power will be coupled through connection  83  to block  75 . It will be realized by those of ordinary skill in the art that for multiple engine applications, connection  83  may include separate connections associated with each of the engines of the multiple engine aircraft. In various embodiments, block  75  includes multiple aircraft starter relays, each one being associated with a starter motor. When power is supplied to block  75  through connection  83 , 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. 
         [0030]    As described above with regards to a single engine aircraft, for a multiple engine aircraft, if power from block  72  reaches block  73  and the anti-theft system is activated, the anti-theft system will disconnect the power supplied from block  72 , and thus not allow power from the aircraft battery of block  71  to power block  74  or block  75 . By not allowing power to reach blocks  74  and  75 , 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 of block  74  are actuated (closed). Thus, when activated, the anti-theft system prevents starting for any of the engines on the multiple engine aircraft. 
         [0031]      FIG. 1B  illustrates a block diagram of one embodiment of an aircraft security system  110 . The embodiment of aircraft security system  110  is similar to the embodiment of system  100 , except that block  74  (aircraft starter switch-single and multiple engine) is coupled to block  72  through connection  81 , and block  74  is further coupled to the anti-theft system of block  73  through connection  82 . The anti-theft system of block  73  is coupled to block  75  through connection  83 . System  110  functions in a similar manner to system  100 . 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. 
         [0032]      FIG. 2  illustrates one embodiment of an aircraft security system  200  including a starter breaker  4  electrically connected to main power bus  3  and a starter switch  5 , where the main power bus  3  is powered by a master switch  2  from a main battery  1 . In various embodiments, main power bus  3  may be an instrument bus. System  200  further includes a security relay  11  having activation means for a first set of contacts  20  and a second set of contacts  21 , where the first set of contacts  20  are normally closed, and are electrically connected to a starter switch  5 , a starter relay  6 , and where the second set of contacts  21  are normally open and are electrically connected to a remote battery  14 , a remote switch  12 , an alarm  13 , and a diode  10 A. A security switch  9  is electrically connected to the security relay  11 . In one embodiment, security switch  9  is a key lock switch. Other embodiments having different types of switches are possible without departing from the scope of the present subject matter. 
         [0033]    System  200  includes one or more modes of operation. In normal, unarmed operation, security switch  9  is open, and the control coil of security relay  11  is de-energized. In this mode, normally closed contacts  20  of security relay  11  will be in a closed state. Activation of the master switch  2  and the starter switch  5  in this mode causes current to flow through the normally closed contacts  20  of the security relay  11 , allowing current flow from main power bus  3  and starter breaker  4 , to the starter relay  6 , which, when energized, closes contacts  22  of starter relay  6 . With contacts  22  closed, power is delivered to starter motor  7  from starter bus  23  through electrical connection  55 , contacts  22 , and electrical connection  56 . 
         [0034]    In another mode of operation of system  200 , security switch  9  is closed. The control coil of security relay  11  is electrically coupled to main power bus  3  through electrical connection  60 , security switch  9 , electrical connection  57 . In one embodiment, diode  10 B couples electrical connection  60  with electrical connection  59 , electrical connection  59  being coupled to security switch  9 . Activation of master switch  2  with a closed (armed) security switch  9  allows current from main battery  1  to flow through master switch  2  to the main power bus  3 , and thus energizes the control coil of security relay  11 , causing normally closed contacts  20  to open. With normally closed contacts  20  open, the current flow from the main power bus  3  to starter relay  6  is disconnected. Starter relay  6  remains de-energized, and contacts  22  remain open. With contacts  22  open, no power is delivered to starter motor  7  from the starter bus  23 . With normally closed contacts  20  open, activation of starter switch  5  will not allow power from main battery  1  to energize starter relay  6 , and thus will prevent starting of the aircraft. 
         [0035]      FIG. 2  illustrates an embodiment of the security system  200  in which at least one application is configured for single engine aircraft. During normal operation, the master switch  2  is closed, allowing battery power from the main battery  1  to flow to the main power bus  3  through electrical connections  50  and  51 . During a normal ignition sequence, current flows from the main power bus  3  through electrical connection  67  to starter breaker  4 , then through electrical connection  52  to starter switch  5 . When starter switch  5  is actuated (closed), current flows through starter switch  5 , and through electrical connection  58  to the normally closed contacts  20  of the security relay  11 . From normally closed contacts  20 , current flows through electrical connection  54 , energizing the control coil of starter relay  6 , and closing contacts  22 , providing power to the engine starter motor  7  from starter bus  23  through electrical connection  55 , contacts  22 , and electrical connection  56 . 
         [0036]    In various embodiments, the security switch  9  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 the security switch  9  is known only to authorized operators of the aircraft. In one or more embodiments, when the owner/operator desires security, the normally open security switch  9  is closed. Once security switch  9  is closed, activating the master switch  2  causes current to flow from the main power bus  3  along electrical connection  57  to the now closed (armed) contacts of the security switch  9 . Power is now available, through electrical connection  60 , to the control coil of security relay  11 , activating security relay  11 . In various embodiments, the path of current flow includes electrical connection  59  and diode  10 B. 
         [0037]    Activation of security relay  11  causes various events to occur. In an embodiment, the energized security relay  11  opens the normally closed contacts  20 , thus opening the start circuit and preventing starter motor  7  from energizing, even when starter switch  5  is actuated, or if starter switch  5  is tampered with. For example even if the “S” and “B” terminals of starter switch  5 , as illustrated in  FIG. 2 , are jumpered or otherwise shorted, the normally open contacts  20  will prevent power from being delivered to starter relay  6 , and thus prevent starting of the aircraft&#39;s engine. 
         [0038]    In various embodiments, the energization of security relay  11  will close normally open contacts  21 . With normally open contacts  21  closed, current can flow from remote battery  14  through electrical connection  61  and through remote switch  12  and through electrical connection  62 , and through the now closed normally open contacts  21  of the security relay  11 . Current then continues to flow through electrical connection  63  and diode  10 A to electrical connection  60 , providing a second source of current flow through the control coil of security relay  11 , keeping security relay  11  energized (latched). In various embodiments, the current flow to electrical connection  63  will allow alarm  13  to become activated. Once latched, security relay  11  and alarm  13  will remain activated even if starter breaker  4  is opened or if the aircraft&#39;s primary power is removed from the main power bus  3  by opening the aircraft&#39;s master switch  2 . Alarm  13  is deactivated by opening the contacts of remote switch  12 . In various embodiments, the function and location of the remote switch  12  is known only to the owner/operator of the aircraft or other authorized persons. 
         [0039]      FIG. 3  illustrates an embodiment where the security system  300  is useful in applications, including, but not limited to, use in multiple engine aircrafts. Reference numbers are repeated for elements of  FIG. 3  which are the same or similar to those of  FIG. 2 . Elements in  FIG. 3  depicting additional iterations of the same or similar elements as depicted in  FIG. 2  are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.” According to various embodiments of system  300 , during normal operation, master switch  2  is activated allowing battery power to flow from main battery  1  to main power bus  3 . During a normal ignition sequence, current flows from main power bus  3  through electrical connection  67  and starter breaker  4 , then through electrical connection  52  to the normally closed contacts  20  of security relay  11 . In various embodiments, the current continues to flow through electrical connections  53 A and  53 B to the normally open contacts of the engine starter switches  5 A and  5 B respectively. In various embodiments, current also flows to additional engine starting circuits, for example, electrical connections  53 C and  53 D to the normally open contacts of starter switches  5 C and  5 D respectively. For purposes of illustration, only the complete starting circuits associated with starter switches  5 A and  5 B 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. 
         [0040]    In one embodiment, starter switches  5 A and  5 B are operated by separate means. In one embodiment, starter switches  5 A and  5 B may be operated at separate times. When starter switch  5 A is activated, current flows through its closed contacts and electrical connection  54 A to the associated starter relay  6 A, energizing the control coil of starter relay  6 A, and closing contacts  22 A. With contacts  22 A closed, current from starter bus  23 A flows through electrical connection  55 A, contacts  22 A, and electrical connection  56 A to power starter motor  7 A. Thus, the starting of the aircraft&#39;s engine associated with starter motor  7 A is enabled. 
         [0041]    When the starter switch  5 B is activated, current flows through its closed contacts and electrical connection  54 B to the associated engine starter relay  6 B, energizing the control coil of starter relay  6 B, and closing contacts  22 B. With contacts  22 B closed, current from starter bus  23 B flows through electrical connection  55 B, contacts  22 B, and electrical connection  56 B to power starter motor  7 B. Thus, the starting of the aircraft&#39;s engine associated with starter motor  7 B is enabled. 
         [0042]    As discussed above, various embodiments of security system  300  include additional electrical connections  53 C and  53 D that are coupled to starter switches  5 C and  5 D 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. 
         [0043]    In various embodiments, the function and location of the security switch  9  is known only to authorized operators of the aircraft. When the owner/operator desires security, security switch  9  is activated (closed). In an embodiment, when security switch  9  is activated and an unauthorized start is attempted, current flows from main power bus  3 , through electrical connection  57  and the now closed security switch  9 , through electrical connection  60 , and to the control coil of security relay  11 , thus activating security relay  11 . In one embodiment, electrical connection  60  is coupled to security switch  9  through electrical connection  59  and diode  10 B. 
         [0044]    When security relay  11  is activated, various events occur. In an embodiment, the normally closed contacts  20  of the security relay  11  open, removing power from the starter switches  5 A and  5 B, and preventing either of the engines from being started, even if starter switches  5 A or  5 B are actuated. In an embodiment, when security relay  11  is activated, the normally open contacts  21  of security relay  11  close, allowing power to flow from the remote battery  14  through the remote switch  12  and electrical connections  61 , and  62 , through the now closed contacts of normally open contacts  21 , and through electrical connection  63  to the audio alarm  13 . Current also flows from electrical connection  63  through diode  10 A to keep the security relay  11  activated (latched) even if the starter breaker  4  is reopened or when the aircraft&#39;s primary power is removed from the main power bus  3  by re-opening the aircraft&#39;s master switch  2 . In one embodiment, once security switch  9  is opened (unarmed), the audible alarm  13  is turned off by opening remote switch  12 . This removes power from the alarm  13  as well as from the control coil of the security relay  11 , unlatching security relay  11 . Unlatching security relay  11  causes normally open contacts  21  to open, and normally closed contacts  20  to close. 
         [0045]      FIG. 4  illustrates an embodiment of the security system  400  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 in  FIG. 5 . Reference numbers are repeated for elements of  FIG. 4  that are the same or similar to those of  FIG. 2 . Elements in  FIG. 5  depicting additional iterations of the same or similar elements as depicted in  FIG. 4  are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.” 
         [0046]    Various embodiments of security system  400  are enhanced to include security switch  9  coupled to main power bus  3  through electrical connection  57  and a circuit protection device, for example, an in-line fuse  26 , is included between electrical connections  57  and  58 . Electrical connection  58  couples circuit  24  of security switch  9  through diode  10 B to electrical connection  60 , which then is coupled to the coil (the control portion) of security relay  11 . When security switch  9  is closed (armed) and master switch  2  is activated, power from main battery  1  flows from main battery  1  through master switch  2  and main power bus  3 , and further through circuit  24  of security switch  9  to energize the coil of security relay  11 . 
         [0047]    Once activated, security relay  11  opens normally closed contacts  20  and closes normally open contacts  21 , latching security relay  11  through remote battery  14  and remote switch  12  while preventing the powering of starter relay  6 , as described above. Further, in various embodiments, alarm  13  is activated when security relay  11  is energized. 
         [0048]    As illustrated in  FIG. 4 , in various embodiments of system  400 , aircraft doors and removable equipment are protected with switches  15  and  16 . In  FIG. 4 , switches  15  and  16  are shown as magnetic switches. However, switches  15  and  16  are not limited to being magnetic switches. In one embodiment, switches  15  and  16  are motion activated. In an embodiment, switches  15  and  16  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, switches  15  and  16  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, switches  15  and  16  are in communication with system  400  using a wireless form of coupling. 
         [0049]    In various embodiments, switches  15  and  16  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 associated switch  15  or  16  is actuated. This allows current to flow from remote battery  14  through electrical connection  61  and remote switch  12 , on through electrical connection  64  and the now actuated contacts of switches  15  or  16 , then on through electrical connection  65  to the circuit  25  of the security switch  9 . If the security system is set on (armed), the circuit  25  of security switch  9  will be closed, allowing current to flow through electrical connection  66  and diode  10 C to activate and latch security relay  11 , as discussed above. In various embodiments, alarm  13  is also activated when security relay  11  is activated or latched. In various embodiments, alarm  13  includes an audible alarm. In various embodiments, the alarm is a silent alarm. In various embodiments, alarm  13  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. 
         [0050]    In one embodiment, activation of security relay  11  will cause normally closed contacts  20  to open, and thus prevent starting of the engine associated with starter motor  7 , even if starter switch  5  is tampered with as discussed above. In an embodiment, alarm  13  is turned off by opening remote switch  12  as discussed above. 
         [0051]      FIG. 5  illustrates an embodiment where the security system  500  is useful in applications, including, but not limited to, use in multiple engine aircrafts. Reference numbers are repeated for elements of  FIG. 5  which are the same or similar to those of  FIG. 4 . Elements in  FIG. 5  depicting additional iterations of the same or similar elements as depicted in  FIG. 4  are shown using the same reference numbers with the addition of a letter, for example, “A” or “B.” 
         [0052]    As illustrated in  FIG. 5 , in various embodiments of system  500 , aircraft doors and removable equipment are protected with switches  15  and  16 . In various embodiments, switches  15  and  16  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 associated switch  15  or  16  is actuated. In various embodiments, switches  15  and  16  are in communication with the system  500  through a wireless coupling. In various embodiments, if either of switches  15  or  16  actuate when security switch  9  is activated (armed), security relay  11  will be energized, and normally closed contacts  20  will open. With normally closed contacts  20  open, power is disconnected from starter switches  5 A and  5 B, and thus activation of either of starter switches  5 A or  5 B, even if tampered with or bypassed, will not enable the starting of either of the aircraft&#39;s engines associated with starter relays  6 A and  6 B. In various embodiments, if provided, additional engine starting circuits, for example, circuits associated with starter switches  5 C and  5 D (associated starter relays and starter motors not shown), would also be disconnected from power, and thus would also disable the starting of the aircraft&#39;s engine associated with that circuit. 
         [0053]    In various embodiments of system  500 , activation of security relay  11  will latch relay  11 . In various embodiments, alarm  13  is also activated when security relay  11  is activated or latched. In an embodiment, alarm  13  is turned off by opening remote switch  12  as discussed above. 
         [0054]    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.