Title of the invention
Temperature Regulator Valve Test Kit for a Fighter Aircraft.
Field of invention
The field of invention relates to air-conditioning system in fighter aircraft during overhauling of fighter aircraft.
Use of invention
The invention is used to carry out pre-installation check and ensure the serviceability of temperature regulator valve on bench.
Prior art
In the prior art the temperature regulator valve had to be installed in aircraft & aircraft had to be fully equipped for carrying out "on board" testing. The serviceability of temperature regulator valve would be completely determined only during engine ground run (EGR).
Draw backs of prior art
In case of temperature regulator valve failure during Engine Ground Run (EGR), the fault diagnosis is a tedious process. Many types of equipments have to be disturbed for gaining access to Temperature Regulator Valve. To re-ensure the serviceability, EGR needs to be carried out, which involves huge fuel consumption cost, man hour cost & aircraft downtime cost.
i. Comparison between prior art and present invention
In the prior art, there was no test kit available carry out pre-installation check and ensure the serviceability of temperature regulator valve before installation on aircraft.

Name of the Applicant: Hindustan Aeronautics Limited, Overhaul Division. Sheet No: 4
. .. .. M Total Sheets: 11
Application No.:
The present invention is a test kit designed & developed to carry out the serviceability of temperature regulator valve. In this method the valve is tested in prescribed test procedure. If all the parameters are found satisfactory, it determines the serviceability of valve.
Aim of the invention
Air conditioning system of fighter aircraft consists of two Temperature Regulator Valves for regulating the temperature in Cockpit & Equipment Bay. The aim of the invention is to carryout pre-installation check of Temperature Regulator Valve thereby avoiding "on board" replacement of temperature regulator valve after failure.
Summary of the present invention
The valve houses DC stepper motor to drive the valve. The shaft of the motor is connected to pinion gear assembly which drives the valve & valve position feedback potential-meter. When valve reaches the end travel, either fully open or closed, a micro switch sends signal to associated electronic unit to shut off power supply to the motor. The invention is a Thvristor controlled PCB with suitable power rating of the component. The thyristor controlled PCB generates three phase DC pulses to drive the stepper motor of the valve. The direction of rotation of the motor is reversed by changing the phase order. The phase order is also changed in the Thyristor controlled PCB.
The invention receives signal from end travel micro switch of valve and as indicator indicates whether the position of valve is fully opened or closed respectively. Also resistance of the feedback potential meter of the valve position can be measured using Ohm meter.
Brief description of drawings
FIG.l Temperature regulating valve (supplied by Original Equipment Manufacturer)
FIG.2 Temperature Regulating Valve Tester
FIG.3 Temperature Regulating Valve Tester Front Panel

Name of the Applicant: Hindustan Aeronautics Limited, Overhaul Division. Sheet No: 5
A .. .. M Total Sheets: 11
Application No.:
FIG. 4- Electronic Circuit Diagram of Temperature Regulating valve Tester
10. Statement of invention
The invention is a pre installation electrical test kit designed and developed to check the serviceability of temperature regulator valve on a test kit before installation on aircraft. Using this test kit, the serviceability of temperature regulator valve can be performed & determined accurately which reduces failure during EGR
11. Detailed description of invention
11.1 Introduction of temperature regulator valve.
The electric valve is a function component of the temperature regulating system in cockpit & equipment bay of supersonic fighter aircraft.
a) Description
The electric valve mainly consist of
• Butterfly Valve
• DC Stepper Motor
• Reduction Gear Assembly
• Potential Meter
• Limit Switch
b) Operation
The electric valve motor is a DC stepper motor. Its rotational direction is reversed when the control phase order is reversed. The shaft in the rotating gear motor consisting of a pinion assembly. This Reduction Gear Motor controls the opening or the closing of the valve and drives a valve position feedback potentiometer.

When the valve reaches end of travel, the valve opened or valve closed. Micro switch sends a signal to the electronic unit associated with the electric valve which shuts off the power supply to the stepper motor.
The Temperature Regulating valve Test kit consists of an electronic circuit. The function of this circuit is to generate 3 phase pulses to rotate the DC stepper motor in both forward & reverse direction. The components used in the circuit are listed below.

In the electronic circuit diagram IC 4011 is used as clock pulse generator to provide input clock pulse to the counter to the IC 4017. In IC 4011 consists of 4 NAND gates, two are used for forward direction & another two are used for reverse direction operation of stepper motor.
IC 4017 is a digital counter plus decoder circuit, the clock pulse is generated at the output of IC 4011 is given as an input to IC 4017 through pin 14.
When a clock pulse is received at the clock input of IC 4017 counter increment, the count AND activates the corresponding output pin.
• When count is zero, pin 3 goes high & all other pin will be low
• After next clock pulse pin 2 goes high & all other pins will be low
• After next clock pulse pin 4 goes high & all other pin will be low
• After next clock pulse pin 7 goes high & this is connected to pin 15 to rest the cycle again the pulse will start from zero to three.
By this three phase pulses are generated at IC 4017 for closing the valve IC U2 is used & for opening the valve IC U3 is used.
The output pins two, three & four of both IC is connected to amplification circuit through diode (BAW14). Diode BAW14 is used to prevent IC 4017 from getting damaged due to reverse voltage from each IC.
The output pulses of 4017 are amplified through Darlington transistor circuit to get 28V pulse at the final output.
The cable consists of 3 looms
1. Cable 001 is used to power the tester from 28V DC power supply.
2. Cable 002 is used to power the tester from aircraft battery box 902A.
3. Cable 003 is used for connecting the temperature regulating valve to tester.
11.2 Testing procedure by using the invention a) Equipment required

• 28V DC power supply
• Ohm meter or multi-meter ■ Insulation tester 50V DC
• Temperature regulating electric valve tester
b) Insulation check
• Measure the insulation strength between all the connector pins combined together and the ground (except for pin "M" which must be connected to the ground) with 50V DC applied.
• The measured resistance should be greater than 40 MQ
c) Function test
• Supply the test unit with 28V DC using cable 001 from 28V dc power supply or supply the test unit with 28V DC using cable 002 from aircraft battery box 902A
• Connect the electric valve to the test unit using cable 003.
• Set the switch S1 in OFF & S2 in close position.
• Set the switch S1 to ON position.
• The electric valve should close when it is fully closed blue indicator light (close) should come ON.

• Set the switch S2 to ON position.
• The electric valve should open. When it is fully open red indicator light (open) should come ON.
• Check that the operating time between full closed to full opened is less than 55 sec
• Check the resistance between P & N should be 2.6KQ ± 0.100KQ & P & R should be 4KQ ± 0.100KQ when valve is fully opened.
• Set the switch S2 to close position.

• The electric valve should close. When it is'fully close blue indicator light (close) should come ON.
• Check that the operating time between full opened to full closed is less than 55sec.
Check the resistance between P & N should be 1KQ ± 0.100KQ & P & R should be 5.6KO ± 0.100KQ when valve is fully closed.
11.3 Advantages of proposed method
• Savings in man hours.
• Identification of failure components in advance.
• Savings in time during production period.
• Customer satisfaction.
12. Drawings & worked examples

Annexure-ll
Title:- Temperature Regulator Valve Test Kit for a Fighter Aircraft. Claims
We claim
1. Design of printed circuit board and electronic circuit diagram of the tester.
2. Selection of electronic components with appropriate power ratings required to drive dc stepper motor in the tester
3. Lay out of the front Panel of Temperature Regulating Valve Tester