AWS EC2 becomes unreachable (Rails, Phusion_Passenger)

Question

My Rails app production is running on AWS EC2 instance, on Apache through Phusion Passenger. And I am facing different problems with it.

1. Sometimes this instance becomes unreachable via ssh and my rails application cannot be accessed via browser. Probably some memory issues. I have created swap memory, but it is not helping.
2. Sometimes my Rails app gets shut down, and application/current folder gets removed.

First one can be fixed only by stopping AWS instance and starting it again, and second one by deploying application.

Any suggestions on what can be causing it? Or even more important how I can fix that once and for all?