Jet Engine Tests

First video shows some testing done on the engine.

Second short video showing what happens when they attach a small explosive charge to one of the blades to simulate what would happen if one of them broke loose from fatigue or fractures that were undetected by maintenance crews. What you're seeing is basically like diamonds cutting diamonds. The engine passes when it can successfully contain the damage. You don't want one of those blades to puncture the fuselage or wing.