GE90-115B Gas Turbine Jet Engine Testing and Evaluation
I takes a lot of money and time to test as thoroughly as the FAA, military, and GE require. More money and time and lives are saved by finding most problems before they become much larger.
Some claim US gas turbine aircraft engines can't take turbulence or odd angles of attack. The claim is clearly false, if you note the shot of the crosswind testing fans. The crosswind fans can simulate hurricane winds at any angle. The fan and the engine can be pivoted to simulate any angle.
Typically it is some former soviet block people that make those claims. They think just because they carelessly showboat fighters at air shows doing extreme AOA, that they are the only ones that can do so. The fact is that we don't make a habit of showboating at air shows because it is risky. The former soviet block has crashed a lot of fighters showboating extreme AOAs. The fact is any time you move a gas turbine with reverse airflow your risk of a flameout increases dramatically. The exhaust can recirculate back into the intake the result can be a backfire or flameout or just reduced power; all can be fatal if you are flying with no margin of error at an air show.
Normally; US pilots are told to avoid doing things that can cause cavitation or recirculation, particularly wile airborne. They are tested at higher altitude in remote areas to give a good chance of recovery, and restart, and if nothing else ejection.
There are some exceptions (sometimes turbofans and turboprops), but it still can be a little risky to the engine.
Note this C-17 backfire. I think there was no real damage to the engine in this case.