An employee was in an aerial lift helping to erect precast tilt-up concrete panels. Approximately 5 minutes after the panel's installation, workers adjusting the panel began to notice it shifting away from its structure. Immediately after noticing the shift, workers started clearing the area. Within seconds, the panel became displaced and completely fell. During the panel's descent, it struck the left side of the employee's aerial lift guardrail. The panel's strike caused the aerial lift to rebound sporadically. The rebounding motions caused the injured employee to strike the left side of his abdomen against the aerial lift's guardrails and platform. This caused him to break his fifth and sixth left-side ribs, and suffer a partially collapsed lung. He was hospitalized.