What is the test for an all-risk policy?

Many cases also say that the hallmark of the all-risk policy is that the loss be fortuitous, in the sense of accidental or at least not inevitable or foreseen. British and Foreign Marine Insurance v. Gaunt. We assume without deciding that the loss here met that test, which seems to be whether, when he bought the insurance, the insured knew of the specific peril. Even if the test asks what is foreseeable, as opposed to foreseen, the question would be what should the insured have known. One may argue in this case that the manufacturer could have reasonably foreseen the disaster. But the trial judge in this case seems to have accepted that the insured, if not the manufacturer, took reasonable precautions at installation, and reasonably could not have discovered the flaw even though with perfect hindsight one could say that the failure was inevitable.