Yes, the timing belt or timing chain is inside the engine casing and it can be bad when it or subordinate parts fail. Though a timing belt/chain failure causing a catastrophic event for the engine itself, I don't think that's very common. What I'm referring to is called the serpentine belt and is often accompanied by what's called an accessory or AC belt.
This description and definition discussion describes very well the definition lawyering and specsheet-rewritting that agile avoids, by having the walking specsheet (customer) sitting in during the creation process.