The delamination
Firstly the terminology is wrong. This is a delamination, not a disbond.
My initial thoughts are that the white surface is suspicious. When composites are supplied there is a release ply on the surface so that the roll of material does not stick to itself on the roll. That release material is usually left in place until the next ply is just about to be laminated over the top of it. The release ply is then removed. If it is not removed, then there is a very high probability of delamination. I suspect that this is the case, but to be sure I would require a sample of the white material.
If this is the case, there has been a QA stuff-up in processing the laminate. Good QA practice would require checking every release ply has been removed either by visual examination prior to the next laminate being applied and/or by reconstructing all of the release plies after the lamination process.
What concerns me about these pictures is the "no disbond" notes on the areas surrounding the delamination. This is a very clear indication of how totally ineffective NDI is. It would be an absolute miracle if that release material was limited only to the delamination area. What is happening is that there is sufficient contact around the delamination between the release ply and the next layer that ultrasound (or tap testing) can not find the release material. It will be there, NDI just can not find it.
People need to understand the limitations of NDI. It can only find some defects when there is an air gap. It is a negative test, not a positive test. Passing NDI is not definite evidence of airworthiness.
Regards
Blakmax
PS Hi Spinwing. Good to hear from you again.