Delamination and blistering
continue to beleaguer boat-builders well over 3 decades after composites became commonplace in the industry. And the "tap-test" is the most current form of looking for problems, provided the area is
accessible to the surveyor...
This joint FAA/DoD/NASA on more modern methods of
"NONDESTRUCTIVE INSPECTION OF COMPOSITES AND THEIR REPAIRS" might offer some insight.
Looks like
FS' ultrasound technique is the way forward...
In 2012, an Air France engineer using ultrasound is inspecting a suspicious bubble in the underbelly of an A-380:
"Mon Dieu! Jacques, come and have a look at zis..."
"Sacré bleu! Eees eet what I think eet looks like?"
"Oui Jacques, she ees with child! A-320s? Twins no less!" 