On September 22, 2005, at 0120 central daylight time, a Convair 440, N181FL, operated by Gulf and Caribbean Cargo, Inc., sustained minor damage during an aborted takeoff from runway 24R (5,499 feet by 100 feet, concrete) at the Kenosha Regional Airport (ENW), Kenosha, Wisconsin. During takeoff roll, the cargo shifted and the airplane settled on its tail. The pilot and copilot were not injured. The 14 Code of Federal Regulations Part 121 cargo flight was repositioning to the General Mitchell International Airport (MKE), Milwaukee, Wisconsin. Night visual meteorological conditions prevailed at the time of the incident. The flight was on an instrument flight rules (IFR) flight plan. The Captain reported that the flight had originally departed Tallahassee, Florida, with cargo to be off-loaded at ENW. After arriving at ENW at about 2350, the flight crew un-strapped the freight, but left the cargo door closed due to thunderstorms in the area. The Captain reported that they waited for 1.5 hours for the ground crew to arrive to off-load the cargo. When the ground crew failed to arrive, the Captain contacted the company. The company requested the flight crew to reposition the airplane to MKE and have the cargo off-loaded there. The flight crew prepared for the flight to MKE by checking the weather and completing the required paperwork. The Captain reported, "Since we un-strapped the freight for off load almost 2 hours ago, we didn't think to check the freight." The Captain reported that they initiated its takeoff roll, but after about 400 feet, the cargo shifted and the airplane's tail struck the runway. The Captain aborted the takeoff and the airplane remained on the runway. The Captain reported that the Before Start Checklist did not remind the flight crew to verify that the cargo was properly restrained. The operator reported that as a result of this incident, the operator will revise the FAA Approved Convair 580 Checklist to include an additional item to verify/confirm that all cargo aft of the cargo net is secured.