[Lotus]

casting marks from the mold surface cracking

I also dipped professionally into casting helping getting the manufacturing process of these to scale. Vacuum centrifugal near net shape casting.
Titanium aluminide exhaust turbine blades for the GE genx engine used on the 787 and 747-8.

 

[Lotus]

"engines stop, passengers swim" was an euphemism used to promote quality.
These things and processes pass a LOT of quality checks. They cost a couple of Gs per piece! And there are hundreds in an engine.