Report: Training a problem

Fischbeck's report said that a key problem faced by NASA was in the training technicians to glue tiles on the hull of the space shuttle and then have them test the strength of the bonding.

An adhesive used for the tiles hardened more quickly if it was wet, and the report said NASA found one technician helping the process along by spitting into the glue. The wetting, however, compromised the bond.

To find loose tiles, workers conducted a pull test, using a special machine, but the study found this technique missed some problems. The most reliable method that was found in the study and that only experienced technicians learned to do, was the "wiggle test"

Loose tiles are more easily knocked off by falling debris.

The link to CNN NASA told in 1990 about vulnerable tiles.

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