PREAMBLE: The invention resulted in development of a special purpose tool used for bending and measuring of Trim tab, to an angle required on the main rotor blade of the skid and wheel version helicopters. The sophisticated tool replaced the earlier manual method, which was in¬consistent, unsafe and time consuming.
FIELD OF INVENTION: This invention relates to design & development of a special purpose tool, which is used for bending and measuring of Trim tab to an angle required on modern helicopters (both skid and wheel version). The tool so developed is portable and capable of bending and measuring of Trim tab to an angle required consistently with less effort.
USE OF INVENTION: The special purpose tool developed, being portable is directly fixed on to the trim tab of the Helicopter. This special tool consists of holder with pointer and bending unit with angular scale. The least count of the scale is 0.5° and maximum measurement up to +/- 5 degree.
The special purpose tool is more reliable and can be used in any condition.
PRIOR ART: The previous process describes manual bending and measuring of trim tab by hand, and measure by bevel protractor. This operation is dependent on group of operator skill & consumes enormous time. The operation had to be carried out more carefully and cautiously as the angle of bending the trim tab will be critical for controlling the vibrations on the helicopter.

OBJECT OF INVENTION
Trim tab is a sheet metal part on the edge of the blade. The trim tab is fixed to the edge of the main rotor blade of the helicopter to balance different planar movements of the blades. These different planar movement of the blade causes vibration in the helicopter. To reduce the vibration caused by the blades due to different planar movement, trim tabs are used. Trim tab will be bent to certain angle for balancing the different planar movement of the blades based on the blade dynamics. The bending and measuring the angle is carried out on helicopter.The special purpose tool ensures the operation of bending the trim tab and angle measurement on helicopter with accuracy and precision.
STATEMENT OF INVENTION:
The invention is a unique, precision, special purpose tool for bending and measuring the angle trim tab of Helicopter main rotor blade. Another unique feature of the tool is its suitability to bend the trim tab as well as measuring the bent angle on the helicopter main rotor blade to carry out precision operation, on a consistent basis. This all together adds to reliability of the tool to operate at any place and at any condition on the helicopter.
DETAILED DESCRIPTION OF THE INVENTION:
The invention relates to design & development of a special purpose tool for bending and measuring the trim tab on helicopter accurately and precisely of both skid and wheel version.The tool is designed for bending the trim tab to the required angle and measuring the angle of the trim tab on the helicopter main rotor blade.The tool consists of a strong & rigid Aluminum alloy two piece holder and two piece bender. Holder is provided with a pointer and spring loaded clamp of thumb screw and nut. this holder will be fixed to the blade before bending and measuring the angle of trim tab. Spring loaded clamps ensures easy fixation and removal of the tool on the blade.The bender is provided with two piece clamping system to fix on to the trim tab for bending and measuring the angle. And it also consists of angular scale and a handle. Angular scale is having least count of 0.5 degree and maximum measurement up to +/- 5 degrees. Handle provided to it helps in ease of operation in bending the trim tab to required angle. Fig.-5 shows the detail parts of the special purpose trim tab bending tool.
SPECIFICATIONS of the bending and measuring tool:
1. Height
2. Length
3. Width
4. Weight of tool
5. Least count angular scale
6. Maximum measurable angle
7. Material
8. Spring loaded clamping
9. Applicability
100 mm 295 mm 225 mm 2.5 kgs 0.5 degree +/- 5 degree Al.Alloy/MS 3 nos On Helicopter
CLAIMS: We claim that
1. This is one of its kind portable special purpose universal tool, designed & developed for bending and measuring the angle of the trim tab on the main rotor of the helicopter.
2. The tool has a quick fixation facility of spring loaded clamps for both holder and bender.
3. The tool ensures safe , easy and quick bending and measuring of trim tab angle on the main rotor blade of the helicopter.
4. Bends the trim tab smoothly and precisely for the required angle.
5. The tool can measure the angle of the trim tab at time of bending.
6. This tool can measure the angle of the trim tab precisely.
7. The tool is easy to set up & operate on the Helicopter main rotor blade and hence does not require highly skilled technicians.