2 things. First, That’s a bad situation, but you knew how old you were and what the pay was when you signed it now live up to your commitment. Not just because you are only as good as your word, but if you do break it you’re always going to have to explain yourself in the future and personally I wouldn’t let you past me in an interview no matter what your explanation is. The only exception is if you live up to the financial part of that contract. It’s got a dollar amount to cancel it, if you pay (or someone else does) then you are living up to your word. If you just run out though, game over.
Second, I wish I could go back a couple decades and redo all the bad decisions I made. 18 may be legally an adult but looking back nearly everything I did and said prior to 25-28 or so was stupid and if it wasn’t, it was dumb luck. You shouldn’t sign any contract for training, ever. If they are making you sign a contract for training then they know the place is garbage and need that to ensure people don’t leave in droves. Especially for a piston twin. Odds are you didn’t even get a type rating out of it. Take this as a lesson for the future, this sort of thing is how places like title loans and payday advance shops operate and avoid it at all costs.