Engine failed during qualification testing, not acceptance testing - so it's a new design.
If you don't occasionally blow an engine up on the stand you are either not testing hard enough or not pushing the limits hard enough.
If you don't occasionally blow an engine up on the stand you are either not testing hard enough or not pushing the limits hard enough.
It may mean they had a simple FOD (foreign object debris) or contamination issue, not a design problem. Powerful oxidizers like liquid oxygen can make contact explosives out of all kinds of organic materials.