Title of the invention

Method to check undercarriage parallelism on fighter aircraft.

Field of invention

This invention is related to the maintenance of supersonic fighter aircraft, during the maintenance of fighter aircraft like Major Inspection, Periodic inspection and rectification of snags check of parallelism of the undercarriage is required to be carried out. This invention relates to a new and simplified method of measurement of parallelism of undercarriage by using a new tool and existing reference point on the aircraft.

Use of invention

This invention is used to measure parallelism of undercarriage of fighter aircraft.

Prior art

This method is unique. Previous method was available which involved obtaining the datum points of the aircraft using plumb bob method. The OEM has prescribed a method of using a set of tools for adjustment of legs. The parallelism will be adjusted after jacking up and levelling the aircraft in a closed hanger. The wheels and the brake unit are removed and adjustment unit are assembled. The plumb bob is dropped from both ends of 2 meter bar and the perpendicular distance is measured with the help of steel rule. Invariably the readings measured were not consistent. The snag of aircraft pulling to one side was repeated during High speed taxiing.

Draw backs of prior art

The previous method was cumbersome, time consuming and prone to errors. The previous method involved identification of the datum points manually by using a plumb bob. Variation in the measurement process was more because of operator errors, parallax errors, wind effect and human fatigue.

comparison between prior art and present invention

The new method is simpler, less time consuming, more accurate, required less number of personnel and least affected by external environmental conditions.

um of the invention

Aim of the invention was to develop an effective and efficient method to measure parallelism of undercarriage of fighter aircraft.

Summary of the present invention

Supersonic fighter aircraft is supported by retractable tricycle undercarriages. Two symmetrical main legs fitted with a wheel & hydraulically controlled disc brakes. A nose leg fitted with a twin wheel steerabte by electro hydraulic system. The undercarriage after installation is to be adjusted for different alignments such as Camber angle, Parallelism, Up lock check on main legs and Caster angle, Camber angle, Parallelism &. Up lock check in the nose leg.

The invention provides a simple and accurate method for measuring the parallelism of undercarriage using a new tool. One part of the tool is screwed on to wheel hub &the other part is hinged on to the rear retaining device slot - a hard point which is a standard reference'point for all fighter aircraft. The set up does not insist leveling of aircraft, perfect level ground & closed hangar space. The free ends of both the parts are coupled to form a right angle. The gap between two reference stops of one of the rods is measured. The measured value is a function of the parallelism. Reference chart shows the correlation of the measured value and the parallelism on the aircraft.

Brief description of drawings

FIG.l: View of Parallelism measurement tool

FIG.2 View of Parallelism measurement tool installed on aircraft.

FIG.3 View of Parallelism measurement tool installed on aircraft Statement of invention

This invented method is much useful for measurement of parallelism of supersonic fighter aircraft in a simpler, faster and more accurate manner.

Detailed description of invention

Refer Fig 1 , 2 and 3

The invention consists of a new tool named TRIPAT and method of measurement of parallelism. The tool is in two parts. One part is 0.5m length & the other part is 2.5m length. The shorter part is screwed on to wheel hub & the other longer part is hinged on to the rear retaining device slot - a hard point. The free ends are coupled to form a right angle. At the end of 2.5m part, gap between two reference stops is measured using a standard Vernier. Parallelism of the undercarriage is computed by correlating the measured value with the available reference chart.

We claim

Methodology used for checking and adjustment of parallelism of undercarriage by using invention (Tool), where measurement and adjustment is simple, direct and accurate. The principle can be adopted for other fighter aircrafts also.

The tool as sembly named has TRIPAT which is used for adjustment of parallelism.

A long bar of 5 meter length, one end is hinged to rear hard point (weapon ' carrying station) and the other end to the 2 meter bar. Fixed and movable reference points between which the parallelism is measured.

Two meter long bar one end threaded to wheel hub and the other end hinged to 5 meter bar.