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Electro Optical Metrology Applications in The Aircraft Industry

Optical Metrology: Optical Alignment Check of Aircraft Jigs

The production of jigs and fixtures for a new aircraft is always a major challenge which increases proportionally with the size of the plane. Jig members must be set parallel and in line to each other. Taylor Hobson Micro alignment telescope provides the solution for this application.

The Micro Alignment Telescope and accessories are used as follows to align the jig members. The jig members are set parallel to each other by being set perpendicular to a common line of sight which is established between a telescope and targets positioned at the jig stations.

It should be noted that the reference line of sight need not be related to any part of the jig structure; for convenience it can be made parallel to the edge of the base, or set horizontal using a Talyvel electronic level or stride level mounted to the Telescope tube. The optical metrology applications in the aircraft industry are described as below.

Optical Metrology: Aero Engine Applications

Aero engines are supplied to aircraft manufacturers and end users as modular units which can be quickly fitted or changed in service with complete interchangeability. During final inspection of the aero engine, it is necessary to check the profile of the engine cowlings relative to the datum mounting points. Positive errors in this area could cause interference between the engine cowling and lower wing surfaces. Difficulty in access to this surface was overcome by using the Taylor Hobson Micro Alignment Telescope with fixtures and optical scales.

Digital Alignment Telescope - Optical Metrology System

The Micro Alignment Telescope can also be used for maintenance of these engines – after a prescribed number of flying hours, overhaul procedures must be carried out. Distortion which has taken place must be checked and, when feasible, repaired by removal of parts of the fabrication and re-welding new components in place. The Micro Alignment Telescope allows engineers to check the change in the attitude of very small holes relative to the component datum. The system can also use a precision clinometer as an aid to the measurement.

Optical Metrology: Helicopters Applications

Helicopters, although much smaller than aeroplanes, use similar technology in their design and construction. Jigs for assembly of the airframe structures are complex and require careful and accurate manufacture and calibration. A problem is to check the distance of a flange face to a plane in space defined by three bores spaced at approximately 2 metre centres. A far simpler and adequately accurate solution was identified using the Micro Alignment Telescope and 4 inch offset optical square when readings are automatically taken.

Optical Metrolgy Application in Helicopter Blade Alignment

Optical Metrology: Satellites Applications

The Micro Alignment Telescope has been used for various applications in the space industry from simple tasks such as setting things truly level with the aid of the Talyvel electronic level, to setting rails parallel and straight to setting platforms in line and square for assembly jigs used for satellite launch rockets.

Optical Metrology Application in Satellite Alignment

Checking of Alignment of Fighter Aircraft Weapons

Various control systems such as those used on fighter aircraft utilise optical systems. The alignment of optical components in a system is complicated and time consuming. It is important to align the various components to the main optical path and in most cases also important to ensure these optical components are also square to the path.

With its unique features of focusing from zero to infinity and its auto reflection capability, the Micro Alignment Telescope can be used to align and set optical components and systemsThe effectiveness of the navigational/attack system of fighter aircraft depends on the accurate alignment check of all systems to the aircraft’s longitudinal fuselage datums (LFD). This is termed harmonization and is normally maintained using the Taylor Hobson Micro Alignment Telescope.

To allow ground crew to check the harmonization, telescopes and collimators (to provide a line of sight) are mounted in a sighting frame and alignment checking jig. This job is made much easier with the use of CCTV or CCD systems to replace the ‘human eye’ or provide digital output.

The first stage of the harmonization sequence is to align the Longitudinal Fuselage Datum jig (LFD) with the Aircraft Target Board (ATB), to provide an accurate datum. Once this is achieved, the target board is then used to align the Internal Navigational Unit (INU) and Pilots Display Unit (PDU).

Checking Alignment of Aircraft Target Board (ATB)

A Micro Alignment Telescope (focused to infinity) is mounted in the Longitudinal Fuselage Datum sighting frame and sighted onto a collimator mounted in the corresponding bracket of the Aircraft Target Board. The frame assembly is then adjusted in elevation and azimuth until the telescope crosslines are centered to the collimator graticules. Any movement that occurs after this setting, is monitored and error corrected.

Optical Metrology Applications - Aircraft Alignment Check

Checking Alignment of Aircraft Internal Navigational Unit (INU)

A Micro alignment telescope located in the INU sighting jig and aligned to the corresponding collimator on the ATB. Any necessary realignment as required is corrected by re-shimming. Similar procedures are adopted to align the PDU and FLIR.

If you would like to know more information about the micro alignment telecope,Talyvel and Clinometers product details please contact us.

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