This document specifies requirements for Emergency Breathing Systems (EBS) for use by helicopter crew and passengers in the event of a ditching or water impact@ to ensure minimum levels of performance. It applies to EBS for use by adults only. Two categories of EBS are addressed by this standard; Category A EBS capable of being successfully deployed in air and underwater and Category B EBS capable of being successfully deployed in air but not underwater. This document is applicable to compressed air@ rebreather and hybrid rebreather designs of EBS.