RVDT
I am really concerned about this issue, not just because of the AW139. I am aware of another European helicopter type where multiple voids in a fibre composite tail boom were repaired by injection repairs and these voids are almost certainly also caused by moisture absorption by the resin system during the production process, which is the same mechanism as I suggest applies to the tail boom problems. The voids were so extensive that the customer insisted on separate repairs on a significant number of shipsets to restore the strength lost by the number of injection holes.
Now, I have a really BIG wheel barrow for injection repairs for voids. I absolutely defy any manufacturer to show me any evidence that injection repairs for adhesive bond or composite laminate production voids restore strength. They fill the disbond and NDI can't find it, but absence of evidence is not evidence of absence. I want to see hard, reliable and irrefutable test data. The surface of a void is fully reacted out during the cure process. It is glazed and slick. Adhesives require a chemically active surface for a bond to form. You do not get that from a slick or glazed surface.
These are both interrelated problems caused by a lack of humidity control in the composites shop.
Now I have no evidence that this current failure is even remotely related, simply because I do not have close-up photos. I would be happy to back off if I could be satisfied that there were no micro-voids in this current case.
I do have close-up photos for the tail boom disbonds and I am prepared to place the family jewels on micro-voiding of the adhesive being the cause. The offical "undiscovered" damage theory for the Doha incident does not explain the other 168 cases of boom disbonds (their figures). Did they all have tail strikes?
So I can't put the wheel barrow away now because the family jewels are in it, and my garden shed is not big enough.
Regards
Blakmax
OK, the big enough comment is a bit of an exageration.