Original Date: 10/20/1997
Revision Date: 01/18/2007
Best Practice : Defect Location Plotting and Zone Mapping
Northrop Grumman’s Product Definition Team on the F/A-18 program uses a unique method of plotting the location of defects and nonconformances, and then mapping these to zones on the aircraft by using 3-D coordinates. All defects and nonconformances are entered into a database with specific locations, identified by x-y-z grid coordinates, that reference back to the aircraft. Figure 2-7 shows how this information is entered into the database. The nonconformances are then sorted by the number of occurrences within a 10x10x10-inch search cube over a selected period of time. The center of the search cube is positioned at each frame station. The time period for sorting and reviewing the data can be selected by the user, but is typically several months to a year.
By sorting and viewing defect data in this way, the user can easily identify trouble areas or defect hot spots by zones on the aircraft. The data also shows the density of problem spots on the aircraft. This information can identify the need to modify work instructions or make engineering changes. For the F/A-18 C/D model, the information captured in the database was limited to hard-to-fix defects and safety-related defects. On the newer E/F model, all defects are entered into the database, and the information is much more extensive. Data on the stable C/D line shows a low density of defects. The limited production E/F line’s data indicates a higher density of defect zones. Figure 2-8 shows an example of three months of data summarized for the E/F line with a detailed breakdown on the number one ranked area of maximum defect density.
The defect location plotting and zone mapping information is available on the F/A-18 website to all authorized users. This information provides an effective way to identify areas of focus for continuous product improvement and provides an excellent way to visualize and track problem densities over time.
Figure 2-7. Sample Input Data
Figure 2-8. Sample E/F Data & Breakdown of Forward Fuselage, Rank 1
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