COMMON NOZZLE ASSEMBLYThe function of the Common Nozzle Assembly (CNA) is to mix the core engine exhaust with the LP compressor (fan) air. The CNA has the shape of a convergent duct which increases the velocity of the mixed gas and thus gives added thrust. The CNA is attached directly onto the LP turbine module of the engine. The CNA is an interchangeable assembly that has an inner and an outer duct assembly. The inner duct assembly is annular and is the primary exhaust nozzle around the core engine exhaust. The outer duct assembly is held by six aerodynamic struts attached to the inner duct assembly. If the CNA is replaced by an other CNA, which doesn't have the same nozzle EPR number, you can enter the new number with the Data Entry Plug (DEP).