The propulsion unit is made up of the engine and nacelles mounted on the pylon which is part of the aft fuselage structure.

The nacelle is designed to house the engine in a smooth aerodynamic casing to keep drag as low as possible and to minimize installation losses.

The nacelle includes the components that follow: 

• The inlet cowls 
• The upper cowls 
• The lower cowls
• The fixed cowls

The pylon is an aerodynamic fairing between the engine and the fuselage. The pylon on which the nacelles are installed is part of the aft fuselage structure.

The pylon includes the engine mount structure and the connections between the aircraft and the engine.

The pylon primary structure includes the components that follow: 

• The nose structure
• The middle structure
• The rear structure
• The engine-mount support spars

 The pylon secondary structure includes the components that follow: 

• The leading edge structure
• The trailing edge structure
• The access panels and skin

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