hobie
Composite structure can be examined using a number of non destructive inspection methods which provide much more reliable and less error prone results than 'tap testing' surface areas the size of small countries with a coin. Even if the engineer inspects with total discipline he/she will only find damage near the surface.
A better method is X-ray, a technique already widely used for matallic structures. Unfortunately there are few of these techniques available for composite as they tend to be driven by 'in service' experience.
Hopefully this incident will drive the industry to find sound and reliable solutions to a long awaited request from maintenance engineers to be equipped with something more elaborate than percussive interpretation.