On March 16, 2000, at 2106 Eastern Standard Time, a passenger was seriously injured when he fell down the stairs of a Beechcraft 1900D, N858CA, operated as CommutAir flight 4480, at the Clinton County Airport (PLB), Plattsburgh, New York. The airplane was not damaged. The captain, first officer, and three additional passengers were not injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan had been filed for the scheduled passenger flight that departed Burlington International Airport (BTV), Burlington, Vermont, at 2015. The flight was conducted under 14 CFR Part 121. According to a written statement from the operator, the flight landed at 2103, and all passengers except one disembarked from the airplane. The last passenger "only had the use of his right arm," and was offered assistance by the first officer to exit the airplane. The passenger refused the assistance, and as he approached the first step of the airstairs, he "lost his balance," and reached for the right side guide cable. The top anchor of the guide cable became disconnected and the passenger fell down the stairs, striking the pavement with his right side. The passenger was transported to a local hospital where he succumbed to his injuries on June 10, 2000. According to a Federal Aviation Administration inspector, the anchor that attached the upper forward cable to the doorframe became disconnected as the passenger proceeded down the airstairs. The anchor bracket, (P/N 50-440037-13), was manufactured from an aluminum casting. The operator, who had problems with the brackets on other airplanes, began to replace the anchor brackets with ones comprised of a stronger material. The accident airplane was due for maintenance in the future, and at that time, the replacement bracket would have been installed. According to the airplane manufacturer, a service bulletin was issued in November 2000, which addressed replacement of the upper anchor brackets for the airstair door forward and aft handrail cables. The replacement was required due to reports of separations of the upper anchor brackets. The bulletin also stated, "Separation of these handrail cable upper anchor brackets can result in the airstair door becoming unstable in addition to loss of handrail support for crew, maintenance personnel or passengers when using the handrail." The new upper anchor bracket (P/N 129-440077-1) was an improved design machined from steel alloy.