I need some help in finding some log pattern in apache logs related to application cash? Is there a specific key word attached related to this event e.g 'crash'.
You could look in the error.log file(s) for 'Apache service started' or similar, when you KNOW Apache was already running. Usually, a crash is silent in the sense that Apache restarts immediately and it can be hard to detect. Specifically if an APPLICATION crashes, but NOT Apache, then you'll have to perhaps look for PHP logs or something.