This SAE Aerospace Standard (AS) defines the requirements for air cycle air conditioning systems used on military air vehicles for cooling@ heating@ ventilation@ and moisture and contamination control. General recommendations for an air conditioning system@ which may include an air cycle system as a cooling source@ are included in MIL-E-18927E (AS) and JSSG-2009. Air cycle air conditioning systems include those components which condition high temperature and high pressure air for delivery to occupied and equipment compartments and to electrical and electronic equipment. This document is applicable to open and closed loop air cycle systems. Definitions are contained in Section 5 of this document.