Flyer, perhaps the operator could be found culpable in a civil case, but not the OEM since how the aircraft are operated and the approved maintenance programmes are not within their control. I am sure the OEM would be seen to be squeaky clean if they provided the technology but the operator discounted it on the basis of a reasonable cost.
Geoffers - you are right. It is those un-thought-of problems that catch everyone out. The thought-of ones are usually no problem!