Molded air bag chute with door reinforced by hollow channel

A passenger air bag system, comprising:

• an instrument panel substrate defining an aperture;
• a chute assembly installed at the aperture;
• and
• an air bag module mounted to the chute assembly and comprising an inflatable air bag for deploying through the chute assembly and aperture;
• wherein the chute assembly comprises:
• an outer flange configured to attach to the instrument panel around an aperture in the instrument panel;
• a tubular chute extending interiorly from the flange to a lower end configured to receive the inflating air bag from the air bag module and defining a deployment path along a longitudinal axis;
• and
• a door flap disposed in an upper end of the chute rotatable from the flange to emerge through the aperture, wherein the flap has 1) an interior side impacted by the inflating air bag carrying a plurality of raised strengthening ribs, and 2) at least one closed-section hollow channel protruding from the interior side to a channel height extending beyond the strengthening ribs.