The Sultan;9850996]It would be the engine.
I thought you had permanently disappeared after your last round of ill informed and totally factually incorrect bashing of the S-92 and individuals on this forum, but then again, maybe your Mother hasn't realized you're back here posting again yet?
It's possible that English isn't your native tongue, or simply that you have never mastered it?
Just for you.
https://en.oxforddictionaries.com/definition/an
It is "AN" engine failure. It is also "AN" engine roll back.