3D Scanners Inspect a NGV using PolyWorks

Photogrammetry Scanning & Inspection of a Nozzle Guide Vane

3D Scanners UK carry out inspection analysis on a damaged Pratt & Witney nozzle guide vane from a Boeing 737-200 jet plane.


A GOM Triple Scan photogrammetry blue light system was used to capture the part. The
Photogrammetry system requires targets to be placed in specific places which are specified on the original CAD drawings. Once in place, photographs are taken from multiple different angles. In this case, a total of 38 photographs were taken from varying angles. The distribution of these targets was crucial as each photo needed to have at least 5 common targets in order to be aligned in the co-ordinate system.

The photographs were then automatically imported into the software and aligned for photogrammetry. A scan of the front & back of the NGV was taken using the GOM system. This was aligned together to provide one single 3d point cloud which was then aligned together within the software.

The engineer attaching reference targets to the NGv
Photographs showing the Gom scanning the NGV.
Photograph above shows the NGV scan on the monitor in the lab.

A polygon mesh was produced for use in deviation analysis.

Target Alignment & Best Fit
The scan data was then imported into PolyWorks where a best fit alignment to the existing CAD was performed. The reference targets were then imported and the measured reference targets were extracted.

All targets were aligned together ready for the creation of an inspection report.

A screenshot showing a cross section taken at a specific point.

Automatic Aerofoil Gauge Extraction
There are 26 different types of measurements within the PolyWorks Airfoil module available. The gauges are fully customisable and can also be re-programmed to meet specific customer requests.

Throat Area Measurement
A throat area measurement was also taken, this can be measured as per drawing, and/or a true minimum area can be measure.

Deviation Colour Map
This shows a deviation colour map with specific points extracted. A full colour PDF report was produced and the workspace was also available to be viewed by the customer using PolyWorks|Viewer.