Elasticbeanstalk scaling

Hi, So we had a weird problem yesterday with elasticbeanstalk. There were about 3 instances running in elasticbeanstalk. Among them only one was healthy and others weren't working. That one instance was preventing from site going down. But, suddenly elasticbeanstalk decided to removed that running healthy instances instead of unhealthy ones. Is there anything that I can do to prevent this in future from happening?