this problem will not go away
You are not wrong, Helispanner. And it will still haunt them for ages unless they address the micro-voiding issue. They must improve their materials acceptance, materials handling and storage, heat-up rates, component preparation and storage, production environment controls and pressurisation methods or they will continue to produce deficient structures. I just hope that they have the expertise and experience to identify and eliminate the most significant factors before they waste money making useless and possible even dangerous parts.
I am surprised that the inspections are limited only to one zone. It may be that this is the critical location for this specific load case, but the causes of micro-voiding are such that the problem may be in every bonded part. In which case some other region may become critical under other load cases.
I am also surprised that there are not weight and manouver restrictions in the AD. Published data I have already referenced indicates a 50% strength loss in overlap joints with micro-voiding. While I don't have hard data, I would not be surprised to see at least an equivalent loss of strength for micro-voided sandwich structure, especially if the adhesive sees out of plane tension. The level of strength loss may even be higher. Now aircraft are designed not to fail at Design Ultimate Load, which is 1.5 times Design Limit Load, the maximum load the aircraft is expected to see once in its lifetime. If the strength is degraded by 50%, then failure may occur at 75% of DLL which means that the structure may be critical within the flight envelope under high loads.
These conclusions are backed up by the known occurrences of disbonds, and there is at least one case I am aware of which occurred on the OTHER side of the boom. While in a number of cases the disbonds appear to be self-arresting and repairable there is always the risk that the disbonds will not arrest as may (in the absence of the final report I stress
may) have occurred in the Doha incident.
I also urge users to inspect the repairs for disbonding. The surface preparation processes described to me for repair have a known history of poor bond durability, so I expect that the repairs themselves will eventually disbond. AW really must address this issue. To repair a disbond with a procedure which will itself disbond is just asking for trouble.
Regards
blakmax