The following specification particularly describes the nature of invention and the manner in which it is to be performed.
BACKGROUND OF INVENTION:
The pylon tester is used to check the serviceability of all the Pylons (Inboard, Outboard and Centerline), Tandem Bomb carrier, 119 ERU and 120 ERU when unloaded and removed from the Aircraft. Also, pylon tester is used to check the continuity and insulation check of the circuits of the carrier or pylon. The imported Pylon tester is having Lamps, switches, indicators, power supply unit and three ladex stepping switches along with Role and Programme change plugs. The technology used is primitive and most of the items are obsolete. Hence, servicing the pylons is severely affected and this affects the serviceability of Jaguar fleet OBJECTIVE OF INVENTION:
The main objective of the invention is to develop new sophiticated Pylon tester replacing the existing unserviceable imported vintage Pylon tester which is under use in servicing the Pylons and weapon carriers of Jaguar Aircraft.
DETAIL DESCRIPTION OF INVENTION:
PYLON TESTER is portable equipment designed specifically to check the continuity of circuits at selected switching lines or loadings, to check the leakage current (Insulation Resistance) between each single line and all other lines and to carry out the functional tests of Pylons/Carriers of Jaguar Aircraft. It operates at 230V AC, 50Hz input supply. The additional facilities provided by the Pylon Tester are as follows:
• Time-delayed outputs for testing the sequential operation of relays in Pylons/Carriers.
• Facility to test functional lines at maximum 5A current rating.
• Provides an option to select 22V or 28V DC supply through software as per the test requirement.
• Facilitates with 22V DC isolated supply for special test requirements.
• Provides 25V AC supply to operate auxiliary units.

PYLON TESTER is designed using a 32 bit Microcontroller with front panel LCD and Keypad switches. The entire test sequence of all the Pylons/Carriers is stored in the microcontroller memory. Using front panel keys/switches the operator can select particular Pylons/Carriers for testing. The test sequences of particular Pylons/Carriers under test will be executed and the test results will be indicated in the front panel LCD. The general view of the newly developed Pylon Tester is shown below.
The main menu of the Pylon Tester has the following testing options:
• Self Test
• Pylons/Carriers Test
• Cable Test
Self Test:
The self test has to be performed in order to know the working status of the tester. The three
main Self tests of the system are as follows.
• Power On Self Test: Standard known combination of resistors are mounted in the
Control Board and are switched in series with either the Continuity test bridges or the

Insulation Check resistors to act as substitutes for lines under test when the Tester itself is being checked. The tested values with Pass/Fail Status will be displayed accordingly. The power on self test checks the serviceability various circuit blocks like continuity measurement, insulation resistance measurement and various derived DC power supplies. It also checks the serviceability of four relay modules. Power on self test will be carried out automatically whenever the tester is switched ON. •- System Self Test: The system self test is carried using the dedicated self test cable, which is provided along with the Pylon Tester. Continuity, Insulation and Functional tests are carried separately during system self test.
• "Auxiliary Power Supply Monitoring Test: This test is carried in order to monitor the
output of auxiliary power supplies used in the system.
Pylons/Carrier Test: The Pylons/Carriers test mainly aims for the test of unit (Pylons/Carriers) under test.
The following Pylons/Carriers can be tested using the PYLON TESTER.
• INBOARD PYLON
• ..OUTBOARD PYLON
• CENTRELINE PYLON
• TANDEM BEAM CARRIER
• ERU NO. 119 PYLON
• ERU NO. 120 PYLON
The above units are tested using corresponding Cable Assemblies/Looms. Testing of the unit under test is divided into three sections as listed below.
• Continuity Test
• Insulation Test
• Functional Test Continuity Test:
This test is performed to check the continuity between two points at selected series load with 28V DC supply. The tester is designed in such a way that it ensures the continuity or no continuity parameter between specified addressed points out of 128 switching lines in the Relay board. This testing is taken care by the Continuity check circuit which is mounted in the

Control board of the tester. The continuity test result is displayed in the LCD. Also there is an option to test the continuity in both direction which facilitates the testing of diodes and other circuit elements. Continuity Test Ranges of theTester:7 Q, 1A and 1.5 0,1 A/5 A Insulation Test:
The Insulation test is carried out by a dedicated circuit block in which the voltage of 28V DC supply is applied through a known series resistor to the line under test. Voltage across the known resistor is measured and hence the leakage current is derived. The leakage current is checked between each single line and all other lines. There are two Insulation resistance test ranges namely 0.5 M Q and 5 M O.
Functional Test: The purpose of Functional test is to check the electrical operations of the circuit elements such as diodes, relays involved in the Pylons/Carriers. There are mainly two circuit block used for functional test of unit under test.
• • Loading Circuit block: A series resistors are switched and any of the single line in a
network undergoing a functional test is loaded with maximum 5A current at 22V DC supply. This circuit block confirms that the line under test is capable of passing the required test current.
• Delay Circuit Block: This circuit has three different time constant network. The selected
timing network switches a timed pulse as required. The range of fixed timing networks is
selected by the microcontroller according to the predefined test sequence of
Pylons/Carriers.
Cable Test:
The tester is provided with 6 dedicated cable assemblies/looms to interface the tester and Pylons/Carriers. These cable looms has to be tested in order to identify the faults in any of the test lines if present. Each cable assemblies/looms has to undergo Continuity, Insulation and Functional tests separately using the Pylon tester and Self test box. -

TESTS CARRIED OUT:
The prototype was developed as per the technical specification cleared by competent design authority. The functional checks of the prototype were carried out at Air Force Station, Bhuj and found satisfactory. Subsequently, the prototype unit was undergone all qualification tests such as Vibration, Low temperature, High Temperature, Humidity, Toppling and bump tests etc as per the qualification test schedule issued by the certification authority. After completion of each qualification test, the unit functional checks were carried out and the performance of the tester was found satisfactory and cleared by the certification authority.
CLAIMS:
1. Obsolescence issue of the tester has been resolved.
2. Servicing/Calibration of tester can be done in our country, Thus becoming self reliant
3. Higher foreign exchange saving achieved..