A fuel transfer system for an aircraft includes an upper tank, a lower tank, a fuel transfer line connecting the upper tank to the lower tank, an upper fuel transfer line outlet in the lower tank, a lower fuel transfer line outlet in the lower tank, an upper float valve associated with the upper fuel transfer line outlet, and a lower float valve associated with the lower fuel transfer line outlet. The upper fuel transfer line outlet, which is in the lower tank, is in fluid communication with the upper tank. The lower fuel transfer line outlet, which is located in the lower tank, is in fluid communication with the upper tank.