[Fot] Testing for Composite Cracking ?

[Group44TR7 at aol.com]

Guys
 
    What would be the cheapest, but reliable testing method to determine if 
crack lines on the surface coating a high performance composite (think 
advanced type composite) are simply cosmetic surface coating cracks or are the 
surface lines of actual fractures in the underlying composite. 
 
    The item being examined is approximately a 1 to 1 1/2 inch diamter 
hollow tube with a wall thickness of about 3/8 inch of the composite at the 
point of observable lines, the object is about 30 inches long. The item must not 
be damaged by the testing procedure.
 
    Thanks in advance.
 
Cary