How long might it have been routinely operated overweight? How much much stress might have all the different components been subjected to after an unknown number of cycles of perf class 1 & 2 takeoffs, helideck landings etc? If it was overweight, was it also way outside C of G?
Of course these questions have to be considered before you can release an aircraft back to service after it has exceeded its design limitations. What if it crashed tomorrow? Do you think the management staff would be justified in saying, "Well, we were only a bit illegal, as its a big aircraft, so we thought we would just ignore it and keep our fingers crossed".
Have you ever heard of a safety culture?