HARNESS INTEGRITY TESTER (HIT)

Abstract: A method and apparatus for determining the conductive integrity of lines which transmit electromagnetic radiation.

Description: This invention pertains to a method and apparatus for determining the conductive integrity of a plurality of lines which transmit electromagnetic radiation. More particularly, the invention is useful for a method and apparatus for determining the conductive integrity of multiple wire cables or harnesses which line the fuselage and wings of sophisticated modern day jet aircraft. The fuselage and wings of sophisticated modern aircraft are lined with multiple wire cables. The cost, both in terms of manpower and equipment, involved in the conventional process of troubleshooting defective cable is substantial. Therefor, it is a principle object of the invention as defined in claims 1 and 2 respectively to provide an improved method and apparatus for determining the conductive integrity of aircraft harnesses and of bundles of electromagnetic radiation transmission lines in general. Such a known method and apparatus, defined by the precharacterizing features of claims 1 and 2, are known from US-A-4 224 690. This and other, further and more specific objects and advantages of the invention will be apparent to those skilled in the art from the following detailed description thereof, taken in conjunction with the drawings, in which: Fig. 1 is a top view illustrating an aircraft harness attached to apparatus constructed in accordance with the invention; Fig. 2 is a top view illustrating an aircraft harness attached to testing apparatus of the invention; Fig. 3 is a top view illustrating a severed aircraft harness attached to testing apparatus of the invention; Fig. 4 is a schematic diagram illustrating the control unit of the invention; and Fig. 5 is a schematic diagram illustrating the detector unit of the invention. Turning now to the drawings, which depict the presently preferred embodiments of the invention for the purpose of illustrating the practice thereof and not by way of limitation of the scope of the invention, Figs. 1-5 illustrate apparatus for testing the conductive integrity of lines for transmitting electromagnetic radiation such as cosmic-ray photons, gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, radio waves, heat and electric current. Cable 11 includes insulative sheathing 12 circumscribing transmission lines or electrically conductive wires 13, 14, 15 and 16 which extend the length of line 11. Each wire 13-16 has a first end and a second end. The first end is secured to and includes connector unit 17. The second end is secured to and includes connector unit 18. Connector unit 17 typically comprises a cannon plug having a pin or pin socket attached to each wire 13-16. For purposes of this description, it is assumed connector unit 17 is a cannon plug having a pin socket 17A attached to each wire 13-16. Connector unit 18 also typically comprises a cannon plug having a pin or pin socket attached to each wire 13-16. For purposes of this description, it is assumed connector unit 18 is a cannon plug having a pin socket 18A attached to each wire 13-16. The control unit (CU) of the testing apparatus of the invention is generally designated by reference character 100 and includes a housing 19 carrying microprocessor 20, switching unit 21, sensor unit 22, power source 23, spring-loaded full load button 24, display lights 25, push button keyboard 26, LED readout 27 and connector means adapted to securely interfit with the existing cannon plug 17 of wire 11 to provide a stable measuring environment and to duplicate the desired continuity of connection between plug 17 and a mating connector unit. As utilized herein, the term "continuity of connection" refers to the losses in electromagnetic radiation which occur when the electromagnetic radiation moving through a line travels through a connection or juncture such as a pin--pin socket connection. The connections offering the best continuity of connection are those which cause the smallest loss of electromagnetic radiation when the radiation travels through the connection. The connector means of the control unit includes pins 28 shaped and dimensioned to slidably interfit into pin sockets 17A of cannon plug 17. Each pin 28 is connected to one of wires 13A, 14A, 15A, 16A leading to sensor unit 22. Wires 13B, 14B, 15B, 16B interconnect switching unit 21 and sensor unit 22. Wires 13A-16A receive electromagnetic radiation signals entering control unit (CU) 100 through connectors 17A, 28 from wires 13-16, respectively. Electromagnetic radiation entering sensor unit 22 through wires 13A -16A exits through wires 13B-16B, respectively. Keyboard 26 includes twelve spring loaded buttons labelled in the same manner as the twelve push buttons on a conventional telephone. Each of the spring loaded buttons on the CU 100 is normally maintained in an "OFF" position. When a button in keyboard 26 is depressed a signal 29 to microprocessor 20 is generated. As soon as finger pressure on a button in keyboard 26 is released, the button moves upwardly to its normal "OFF" position. Full Load Test button 24 is also spring loaded and is normally in an "OFF" position. Depressing button 24 displaces it to the "ON" position. Once finger pressure on button 24 is released, the button moves upwardly to its normal "OFF" position. The display lights 25 include red stray signal indicator 30, green power present indicator 31, and amber continuity indicator 32. Display lights 25 are controlled 33 by microprocessor 20. When Full Load Test button 24 is depressed and held for two seconds it causes a signal 32 to be sent to microprocessor 20. LED readout 27 produces an alphanumeric readout on command 35 from microprocessor 20. Power source 23 is presently preferably a battery internally mounted inside housing 19 of CU 100. However, power can be supplied to CU 100 by any other appropriate internal or external source. Microprocessor 20 receives signals 36 from monitoring circuitry inside power source 23 indicating the operational status of source 23 and its ability to deliver to switching unit 21 the quantity of power required by microprocessor 20. Microprocessor 20 controls 38 the amount of power transmitted 37 by power source 23 to switching unit 21. When a particular wire 13-16 is selected for continuity testing by depressing the appropriate buttons in keyboard 26, microprocessor 20 commands 39 switching unit 21 such that power 37 from source 23 is directed through switching unit 21 and onto the wire 13-16 selected at keyboard 26. Sensor unit 32 provides 40 microprocessor 20 with data indicating the quantity or other physical characteristic which indicates either the quantity and/or quality of the electromagnetic radiation traveling along wires 13-16. The detector unit (DU) of the testing apparatus of the invention is generally designated by reference character 200 and includes a housing 49 carrying microprocessor 50, sensor unit 52, spring-loaded Full Load Test button 54, display lights 55, push button keyboard 56, LED readout 57, and connector means adapted to securely interfit with the cannon plug 18 or wire 11 to provide a stable measuring environment and to provide the desired continuity of connection with plug 18. The connector means of the detector unit (DU) 200 includes pins 59 shaped and dimensioned to slidably interfit into pin sockets 18A of cannon plug 18. Each pin 59 is connected to one of wires 13C, 14C, 15C, 16C leading to sensor unit 52. Wires 13C, 14C, 15C, 16C receive electromagnetic radiation entering DU 200 through connectors 18, 59 from wires 13-16, respectively. Electromagnetic radiation entering sensor unit 52 through wires 13C-16C exits sensor unit 52 through wires 13D-16D, respectively. Wires 13D-16D interconnect sensor unit 52 and switching unit 69. Microprocessor 20 controls 70 switching unit 69. Keyboard 56 includes twelve spring loaded buttons labelled in the same manner as the twelve buttons on a conventional push button telephone. Each of the DU push buttons is normally in the "OFF" position. When a push button in keyboard 56 is depressed, a signal 60 to microprocessor 50 is generated. As soon as finger pressured on a push button in keyboard 56 is released, the button moves upwardly to its normal "OFF" position. Full Load Test button 54 is also spring loaded and is normally in an "OFF" position. Depressing button 54 displaces it to the "ON" position. Once finger pressure on button 54 is released, the button moves upwardly to its normal "OFF" position. Display lights 55 include red stray signal indicator 61, green full load indicator 62, and amber continuity indicator 63. Display lights 55 are controlled 68 by microprocessor 50. When Full Load Test button 54 is depressed and held for two seconds, it causes a signal 64 to be sent to microprocessor 50. LED readout 57 produces an alphanumeric readout on receiving a command 65 from microprocessor 50. When a particular wire 13-16 is selected for testing by making the appropriate entry on keyboard 56, microprocessor 50 receives signals 66 from sensor unit 52 indicating either the quantity or other physcial characteristics which indicate the quantity or other physical characteristics which indicate the quantity and/or quality of electromagnetic radiation passing through wire 13-16. The operation of the apparatus of the invention is, with reference to Figs. 1 to 3, further illustrated below in TABLES I-III. For purposes of the troubleshooting procedures described below in TABLES I-III it is assumed the cable 11 in Figs. 1 to 3 is in a present day jet aircraft, includes at least one bulkhead connector 67 therein, has a first end including cannon plug 17, and has a second end including cannon plug 18. Prior to the testing procesures of TABLES I-III, cannon plugs 17, 18 are disconnected from their mating connectors in the aircraft and are connect to connector means of the CU 100 and DU 200, respectively in the manner depicted in Fig. 1. The mating connectors of plugs 17, 18 in the aircraft are typically associated with a computer or LRU. The connector means in CU 100 and DU 200 are essentially a duplicate of the aircraft mating connectors and each include four pins which each slidably interfit with one of the four pin sockets of plug 17 or plug 18 to provide a connection with plugs 17, 18 which produces a high continuity of connection and causes minimal losses of electromagnetic radiation when radiation from wire 13-16 travels through the pin--pin socket connections into or from CU 100 or DU 200. In TABLES I-III reference is made to alphanumeric readouts on the CU LED readout 27 and the DU LED readout 57. The meaning of these readouts is as follows: Readout Meaning PT Pin test DS Dead short SS Stray signal SP Signal present FL Full load When numerals appear in the readouts, the numerals indicate the wire associated with the particular letter readout. Letter readouts generally always occur in conjunction with a numerical readout. For example, "PT 13" means wire 13 is being tested; "SS 14" means there is a stray signal (short) on wire 14; "SP 15" means there is a signal present on wire 15. CU 100 and DU 200 can be constructed from existing off-the-shelf electronic components and can, depending on the size of a cannon plug 17, 18, often be sized to be carried in the pocket of an individual. It is anticipated that each CU 100--DU 200 pair will be constructed for testing a cable which is built to carry a certain current and voltage and has cannon plugs or other connector means of a particular shape and dimension. The connectors 28, 59 on the CU and DU would be constructed to readily mate with the cable cannon plugs or other connector means to provide cable--CU and cable--DU interfaces having the proper conductive continuity. Structure and other information peculiar to a cable, for instance the existance of built-in jumpers between wires, would be programmed into the microprocessors provided in CU 100 and DU 200. While the transmission lines used to transmit electromagnetic radiation are, in the drawings and in TABLES I-III, described as electrically conductive wires, the lines can be constructed as appropriate to carry other types of energy. For example, transmission line 12 can be a fiber optic cable for conducting light or can be a hollow tube for conducting heat or radio waves. CU 100 and DU 200 need not include microprocessors in order to function in accordance with the invention. CU 100 can comprise a mechanical switch which can connect a line or wire being tested to a battery or other power source. DU 200 can comprise a mechanical switch which can connect the line or wire being tested with an appropriate load and an indicator light(s). The DU would include means for individuallly checking or simultaneously monitoring each wire or line in a cable to determine if current is present in the lines when a signal is sent by the CU over the line being tested. For example, in Fig. 4 microprocessor 20, LED readout 27, and keyboard 26 can be eliminated. Switching unit 21 can include a mechanical switch which, when rotated to the wire 13-16 being tested, permits current from power source 23 to only flow over the wire being tested. Sensor unit 22 can include a switch which causes current on any wire other than the wire being tested to flow 90 to and illuminate stray signal indicator 30. In place of or in addition to indicator 30 there can be an indicator light connected to each wire 13-16 so that the particular wire carrying the stray signal can be identified. The indicator light for each wire would illuminate when current passed through the wire. In Fig. 5, microprocessor 50, LED readout 57, and keyboard 56 can be eliminated. Switching unit 69 can include a mechanical switch which, when rotated to the wire being tested, permits current flowing through the wire being tested to flow 91 to and illuminate amber continuity indicator 63. Sensor unit 52 can include a mechanical switch which causes current on any wire other than the wire being tested to flow 92 to stray signal indicator 61. In place of or in addition to indicator 61 there can be an indicator light connected to each wire 13-16 so that the particular wire carrying the stray signal can be identified. The indicator light for each wire would illuminate when current flowed through the wire. If desired, means can be provided for transmitting from the CU microprocessor 20 to the DU microprocessor 50 either the identify of the wire being tested on the CU or other information. As noted, during the full load test, the DU microprocessor 50 monitors sensor unit 52. Sensor unit 52 detects the voltage in the wire being tested. Microprocessor 50 can, if desired, be programmed to cause LED readout 57 to display either the voltage or the voltage drop in the wire being tested. A user, when an aircraft of other machine or device is functioning properly or is new, uses the CU 100 and DU 200 to determine the voltage drop or other measurable characteristic in each wire in each cable in the device. This "voltage drop calibration-reference data base" is retained in the maintenance records of the aircraft. When there subsequently is a malfunction or a periodic maintenancing of the aircraft which requires the voltage drop in a wire to be remeasured, the new measurement is compared with the voltage drop calibraction-reference data on the wire. This comparison of new data with the voltage drop calibraction-reference data is crucial to the proper mantenance of an aircraft and greatly facilitates troubleshooting of malfunctions and the early detection of flaws in a cable. Further, flaws in a cable are often detected during the initial testing of a cable to generate the voltage drop calibration-reference data base.

Claims: A maintenance system for detecting, in each of a plurality of cables (11), faults which cause attenuation of electromagnetic radiation transmitted through the cable, each of said cables including a plurality of lines (13-16) extending the length of the cable, each of said cables having a first end including first connector means (17) and having a second end including second connector means (18), each of said plurality of lines terminating at said first and second connector means, each of said first and second connector means normally being removably connected to mating means in a system, each of said connector means being disconnected from said mating means during utilization of said maintenance system, said maintenance system including: (a) a transportable control unit (100) including: (i) means (28) for attaching said control unit to said first connector means (17) of a selected one of said cables to connect said control unit and the selected cable, and (ii) control means (20, 21, 22, 23, 24, 26) for selectively directing continuity evaluation electromagnetic radiation into a selected one of said lines at said first end of the selected cable, (b) a transportable detector unit (200) including: (i) means (59) for attaching said detector unit to said second connector means (18) of the selected cable (11) to connect said detector unit and the selected cable, and (ii) sensor means (52) for measuring the quantity of electromagnetic radiation reaching said second end of the selected cable in each of said lines when said control means directs said continuity evaluation electromagnetic radiation into said selected line at said first end of the selected cable, said sensor means measuring continuity evaluation-fault detection information for each of said lines when said control means directs said continuity evaluation electromagnetic radiation into said selected line at said first end of the selected cable, (iii) storage means (50) for storing continuity evaluation-reference information which serves to indicate which of said second ends of the lines should normally produce an output of transmitted electromagnetic radiation when said first quantity of electromagnetic radiation is directed into said lines at said first end of said plurality of cables, said storage means including means for recalling said continuity evaluation-reference information stored therein for each of said lines; and (iv) comparison means (50) coupled to said sensor means and coupled to said storage means for comparing said continuity evaluation-fault detection information with said recalled reference measurement information and generating continuity fault-identification information (63) in response to such comparison; said maintenance system being characterised in that: (c) said continuity evaluation electromagnetic radiation is relatively minimal in degree by comparison to the amount of electromagnetiC radiation normally conducted by each of said lines of the selected cable under normal load conditions and serving merely to confirm that such electromagnetic radiation reaches the second end of the selected cable; (d) said control means (20,21,22,23,24,26) is also operable selectively to direct load evaluation electromagnetic radiation into said selected line at said first end of the selected cable, said load evaluation electromagnetic radiation being relatively similar in degree to the amount of electromagnetic radiation normally conducted by each of said lines of the selected cable under normal load conditions; (e) said sensor means (52) also measuring load evaluation fault detection information for each of said lines when said control means directs said load evaluation electromagnetic radiation into said selected line at said first end of the selected cable; (f) said storage means (50) also storing as load evaluation-reference information for each of said lines, nominal quantities of electromagnetic radiation measured for each of said lines at said second end of a plurality of said cables when said load evaluation electromagnetic radiation is directed into said lines at said first end of said plurality of identical cables, said storage means including means for recalling said load evaluation-reference information stored therein for each of said lines; and (g) said comparison means (50) also comparing said load evaluation-fault detection information with said recalled load evaluation-reference measurement information and generating load fault-identification information (62) in response to such comparison A method of detecting, in each of a plurality of cables (11), faults which cause attenuation of electromagnetic radiation transmitted through the cable, each of said cables including a plurality of lines (13-16) extending the length of the cable, each of said cables having a first end including first connector means (17) and having a second end including second connector means (18), each of said plurality of lines terminating at said first and second connector means, each of said first and second connector means normally being removably connected to mating means in a system, said method including the steps of: (a) generating continuity evaluation-reference measurement information for said cables by: (i) detaching said first and second connector means (17,18) for a plurality of said cables (11) from said mating means; (ii) directing continuity evaluation electromagnetic radiation into each of said lines of said cables at said first end of each cable at said first connector means thereof to generate continuity evaluation-reference information for each of said lines of said cables at the second ends thereof, (iii) determining which of said second ends of said lines for each of said cables at said second connector means thereof produce an output of transmitted electromagnetic radiation when said continuity evaluation electromagnetic radiation is directed into said lines at said first end of each cable, said determination providing continuity evaluation-reference information for each line of said plurality of cables; (iv) storing said continuity evaluation-reference information; (b) generating continuity evaluation-fault detection information in a selected one of said cables by: (i) detaching said first and second connector means of said selected cable from said mating means; (ii) directing through each of said lines in said selected cable said continuity evaluation electromagnetic radiation; (iii) determining continuity evaluation-fault detection information by establishing which of said lines at said second end of the selected cable produce an output of electromagnetic radiation when said continuity evaluation electromagnetic radiation is directed into said lines in Step (b) (ii); and (iv) recalling said continuity evaluation-reference information and comparing said continuity evaluation-reference information with said continuity evaluation-fault detection information to generate continuity fault-identification information, said continuity fault-identification information identifying variances between said continuity evaluation-reference information and said continuity evaluation-fault detection information; said method being characterised in that said continuity evaluation electromagnetic radiation being relatively minimal in degree by comparison to the amount of electromagnetic radiation normally conducted by each of said lines of said identical cables under normal load conditions and serving merely to confirm that such electromagnetic radiation reaches the second end of each such cable, and the further step of: (c) generating load evaluation-reference measurement information for said cables by: (i) detaching said first and second connector means for a plurality of said identical cables from said mating means; (ii) directing a load evaluation electromagnetic radiation into each of said lines of said cables at said first end of each cable at said first connector means thereof to generate load evaluation-reference information for each of said lines of said cables at the second ends thereof, said load evaluation electromagnetic radiation being relatively similar in degree to the amount of electromagnetic radiation normally conducted by each of such lines of said cables under normal load conditions; (iii) measuring the quantity of electromagnetic radiation reaching said second end of the cable in each of said lines for each of said identical cables at said second connector means thereof when said load evaluation electromagnetic radiation is directed into said lines at said first end of each cable, said measured quantity representing load evaluation-reference information, for each line of said plurality of cables; (iv) storing as load evaluation-reference information the quantity of electromagnetic radiation measured at said second ends of the cable when said second load evaluation of electromagnetic radiation is directed into said lines in Step (c) (ii) above; (d) generating load evaluation-fault detection information in a selected one of said cables by: (i) detaching said first and second connector means of said selected cable from said mating means; (ii) directing through each of said lines in said selected cable said load evaluation electromagnetic radiation; (iii) measuring as load evaluation-fault detection information the quantities of electromagnetic radiation measured in said lines at said second end of said selected cable when said load evaluation electromagnetic radiation is directed into said lines in Step (d) (ii) above and (iv) recalling said load evaluation-reference information and comparing said load evaluation-reference information with said load evaluation-fault detection information to generate load fault-identification information, said load fault-identification information identifying variances between said load evaluation-reference information and said load evaluation-fault detection information. The maintenance system of claim 1, wherein said continuity evaluation electromagnetic radiation is an electrical current in a range of approximately 3 milliamps to 30 milliamps. The method of claim 2, wherein said continuity evaluation electromagnetic radiation is an electrical current in a range of approximately 3 milliamps to 30 milliamps. The maintenance system of claim 3, wherein said load evaluation electromagnetic radiation is an electrical current in a range of approximately three to ten amps. The method of claim 4, wherein said load evaluation electromagnetic radiation is an electrical current in a range of approximately three to ten amps.

Inventors: SULLIVAN, THOMAS P.
Applicants: SULLIVAN, THOMAS P.
Application year: 1987
Main classification: G01R31
IPC codes: G01R31