1 Field of Invention
The present invention relates to the test equipment for vibration warning systems of vehicles and in particular, to vibration simulators as test equipment for vibration warning systems of helicopters.
2 Background of the Invention
Helicopters experience high levels of vibration due to the rotating main rotor and tail rotor systems. Vibration warning systems are used to monitor the vibrations and provide warnings to the fight crew if the vibration exceeds safe limits.
Vibration warning systems utilize sensors to measure rotor rotation speeds or rpm and amplitude of vibration and a processor to analyze the data to trigger a warning if preset vibration limits are exceeded. These limits are prescribed for vertical and lateral vibration of the main rotor, and radial & axial vibration of the tail rotor. The warning triggered by the processor is transmitted to the cockpit and displayed.
Whether the vibration warning system will generate warnings when limits are exceeded is verified by virtue of warnings generated during flight trials. If the vibration level is high, corresponding warnings are triggered. If the warning system is defective, even if the vibration exceeds safe limits in flight, no warnings will be generated or displayed, thereby compromising the safety of . flight. In prior art and industry practice, there is no method to verify if this functionality of the vibration warning system is faulty or not working. There is also no means to detect if the triggered warning is not displayed in the cockpit due to faulty wiring.

US8131420 describes a Health and Usage Monitoring System to monitor the health and usage of engine and/or drive components of various vehicles. The system employs wireless sensors that transmit vibration data of the vehicle's components to a data access point for health and usage monitoring. However, no mention is made of a warning system or a test kit to verify the warning functionality.
There is a need to for ground test equipment for the helicopter vibration warning system that can verify whether the vibration warning system will trigger a warning for high vibration without fail during operation and to detect the presence of any fault that prevents display of the triggered warning.
3 Brief Summary of the Invention
The present invention addresses the above need by providing a vibration simulation kit to test the helicopter vibration warning system. Using a microcontroller with a combination of resistors and other necessary interfaces with the warning system, the vibration simulation kit electrically simulates the signals generated by actual helicopter vibration and feeds it to the warning system, thereby making it possible to test the vibration warning system for proper functioning.
4 Description of the Drawings
Figure-1 is a block diagram with the interfaces of the test box and describes the various components involved when the vibration simulator 1 is set up to test the vibration warning system 6 of a helicopter..
Figure-2 illustrates the components of the test box 1 which are operated for testing.

5 Detailed Description of invention
It should be noted that while the specification and appendices describe a vibration simulation kit for the helicopter tail rotor, other embodiments of the present invention may be used for simulating vertical and lateral vibration of helicopter main rotor as well. It may also be used for vibration simulation for testing of other vehicles.
Figure-1 shows the components used when using the vibration simulator for testing the helicopter vibration warning system. The test box 1 is connected to the connector of the radial sensor of the tail rotor 2, connector of the axial sensor of the tail rotor 3, connector of the tail rotor rpm sensor 4 and connector of the main rotor rpm sensor 5. As part of the helicopter wiring, connectors 2, 3, 4, and 5 are already connected to the processor of the vibration warning system 6 on the other end, which is connected to the cockpit display 7.
The test box itself is shown in Figure-2. It contains a microcontroller that acts along with a combination of resistors and capacitors to behave as a function generator to provide frequency and vibration amplitude signals. The test box has an on/off push-button 1-A for power supply. The tail rotor vibration is measured with radial and axial sensors, so the test box includes a two-pole switch to toggle between simulation of axial and radial vibration 1-B. The vibration warning system has two. warning thresholds- the first threshold is 'HIGH' and a higher threshold is 'EXCESS". A rotary knob 1-C is provided for selection of simulation of NORMAL, HIGH or EXCESS vibration levels. The test box also has mating connectors, 1-D, 1-E, 1-F and 1-G to transmit vibration amplitude and rpm signals to the processor 6 through connectors 2, 3, 4 and 5 shown in Figure-1.

Helicopter vibration warning systems have continuous vibration monitoring modes, known as Monitor Modes, as well as modes for more accurate measurement of the vibrations, known as 'Measurement Mode'. Monitor modes require main rotor rpm as input frequency. The microcontroller in the test box 1 provides this simulated main rotor rpm through mating connector 1-G of Figure-2 to connector 5 of Figure-1, thereby making it possible to test the vibration warning system functionality in both modes.
The vibration simulator provides a means of testing the vibration warning system on ground without the rotor running. By using this test kit, it becomes possible to ensure the proper functioning of the vibration warning system before the helicopter is flown.
By testing the system in its installed condition in the helicopter, it becomes possible to ensure that the triggered warnings are displayed I the cockpit. This is important in the flight safety perspective as it ensures that the critical vibration warnings generated by the vibration warning system are not missed by the flight crew.
While the particulars disclosed above are only representations, it is also possible that the invention may be modified and practiced in equivalent but different ways or arrangements by one who is skilled in the art with the help of the details described in this manuscript. Therefore, all such variations are considered within the scope and spirit of the invention. Accordingly, the protection is sought.

Claims -
5 We claim,
1. A vibration simulator kit 1 and mechanism for simulation of helicopter rotor
rpm and rotor vibration to test the warning functionality of helicopter vibration
warning system 6, comprising:
- a switch 1-C to toggle between measurement of axial vibration and 10 radial vibration simulation;
- a plurality of switches to test additional vibration parameters like main
rotor vibration are also within the scope;
- a rotary knob 1-B or similar provision to test the functionality of the
vibration warning system at different vibration levels, catering to the
15 warning thresholds of HIGH and EXCESS available in the vibration
warning system, wherein said provision can also be extended to more levels; and
- a provision 1-G for main rotor rpm input to check the warning
functionality in 'monitor' and 'measurement' modes of the vibration
20 warning system.
2. The vibration simulator kit 1 and mechanism for simulation, as claimed in
claim 1, wherein, the kit helps to detect fault in the processor unit of vibration
warning system to check whether warning gets triggered appropriately or not.
3. The vibration simulator kit 1 and mechanism for simulation, as claimed in
25 claims 1-2, wherein the kit helps to detect any fault in the wiring from the
vibration warning system processor 6 to the display in the cockpit 7.
4. The vibration simulator kit 1 and mechanism for simulation, as claimed in
claims 1-3/rwherein, the kit provides .a safe means of tesfflng the warning

function of the vibration warning system without actually running the helicopter saving fuel and effort, and
5. The vibration simulator kit 1 and mechanism for simulation, as claimed in claims 1-4, wherein the kit provides a safe means of testing the warning function of the vibration warning system after any modification of the system.