The pylon is an aerodynamic fairing between the engine and the fuselage. Access is supplied to the inner side of the pylon for inspection and maintenance. Vent and drain holes are also supplied.

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

The pylon primary structure includes the following:

Nose Structure

The nose structure is found between FS877.25 and FS909.75. The nose and middle structures are made from aluminum alloy. It includes ribs, angles, channels, and doublers.

Middle Structure

The middle structure is found between FS909.75 and FS1030.2. It includes webs, ribs, spars, angles, and an engine firewall. The firewall is found between FS907.75 and FS987.055. The firewall is the point where connections between the engine and the aircraft are made. The firewall is made of one aluminum sheet made stronger with cap angles and doublers.

Rear Structure

The rear structure is found between FS1030.20 to FS1080.00. It is made of a set of Kevlar ribs held together with rivets.

Engine-Mount Support Spars

The engine-mount support spars include the components that follow:

• The forward engine-mount support spar
• The aft engine-mount support spar

The forward engine-mount support spar is found at FS925.00. The forward engine-mount support spar includes two fittings that are held together with rivets. The fittings are made from steel.

The aft engine-mount support spar is found at FS987.055. The aft engine-mount support spars and two support ribs are made from steel.

The inboard ends of the forward and the aft engine-mount support spars are held with rivets to the rear fuselage frames. The outboard ends of the spars hold the forward and aft engine mounts.

The secondary structure consists of the leading edge, the trailing edge, the access panels and the skins.

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