The inferno inside a jet engine is hotter than the surface of the sun. Something for the 911 Truthers to think about with their back yard BBQ’s. Perhaps the planes slamming into buildings can generate more than the average amount of heat. The twin towers will not have had anything like the same airflow as an engine.
Apparently engineers use computer models to shape that airflow inside a jet, and only then design the fan blades that can move air exactly as needed. That’s why the turbine blades don’t melt. More on Jets here