What was found
CLT/HTS - FLT 5100 - FLIGHT HAD JUST TAKEN OFF, FLIGHT CREW SELECTED GEAR UP, BUT, THE GEAR DID NOT RETRACT. THE CREW SELECTED GEAR DOWN AND RETURNED TO CLT FOR AN UNEVENTFUL LANDING. MAINTENANCE PERSONNEL WERE DISPATCHED TO TROUBLESHOOT THE PROBLEM. THE EMERGENCY LANDING GEAR BYPASS PIN WAS FOUND POPPED. THE PIN WAS RESET AND THE AIRCRAFT WAS RETURNED TO SERVICE.