Laser measurement of turbine blade pitting

Citation

(2006), "Laser measurement of turbine blade pitting", Aircraft Engineering and Aerospace Technology, Vol. 78 No. 3. https://doi.org/10.1108/aeat.2006.12778cad.002

Laser measurement of turbine blade pitting

Laser measurement of turbine blade pitting

Keywords: Jet engines, Aircraft components

Accurate measurement of pitting on turbine blades is now possible using the LaserGauge system available in the UK only from Luton-based QGS. Inspection for pitting on jet engine turbine blades poses a major headache for maintenance engineers.

If the pitting is severe, the blade cannot be repaired and must be scrapped – the difficulty lies in separating those blades that can be repaired from those which cannot.

Naturally, in aerospace, safety is paramount, and, in the absence of an accurate way of measuring the pitting, this has led to the scrapping of large numbers of valuable turbine blades which could safely have been repaired.

Up to now pitting-depth has either been assessed using visual inspection and comparison with known examples or templates, a method prone to human error and lack of repeatability, or by optical comparator equipment – which is cumbersome and lacks portability.

Using a high resolution LaserGauge system both these drawbacks are said to be eliminated.

Pitting can reportedly be measured to an thousandth of an inch, with the results of the inspection being automatically documented on a graph together with dimensional data.

Furthermore, because the LaserGauge system is both wireless and portable, several engines can be inspected at the same time over a wide area in the repair facility.

Operation of the LaserGauge equipment is described as very simple; the operator positions the laser stripe over the pit and releases the trigger.

The edges of the pit are found based on a selected tolerance, the greatest depth of the pit, any material that has been pushed up above the parent surface, and the width of the pit, are all calculated and displayed in the data table.

Using the LaserGauge to measure pitting can provide significant financial savings – when blades can be salvaged for repair rather than scrapped, as well as offering major time-savings, because inspections can be performed at the repair site, obviating the need to transport blades to a laboratory.

Furthermore, all the measurements undertaken are documented and repeatable and the results are traceable.

Similar benefits can also be obtained using the high resolution LaserGauge system in situations where corrosion or hairline cracks must be measured to determine the feasibility of repairing worn items, for example, gears.

For further information, contact: Quality Gauging Systems. Tel: +44 (0) 870 143 3020