On August 11, 1999, approximately 0830 mountain daylight time, a Balloon Works Firefly 9, N2570E, owned and operated by Colorado Balloon Services, sustained minor damage during a landing in a field 9 miles east of Hartsel, Colorado. The commercial pilot and five passengers were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the personal flight being conducted under Title 14 CFR Part 91. The flight originated near Hartsel approximately 0730. In his incident report, the pilot said that as he approached the touchdown point, he flared the balloon and pulled the deflation line. The line broke and fell into the basket. Unable to deflate the balloon (because the line had broken approximately 5 feet down from the parachute harness and 40 feet up from the skirt inside the envelope), the pilot radioed his ground crew for assistance. The balloon was secured long enough for the passengers to exit, then the wind velocity increased. It broke free and dragged across the ground. The pilot caught the balloon and cut holes in the middle portion of the envelope. The envelope deflated to the extent that he was able to grab the upper portion of the deflation valve and complete the deflation process. According to Title 49 CFR Part 830.5(a)(1), "The operator of an aircraft shall immediately, and by the most expeditious means available, notify the nearest National Transportation Safety Board field office when [there has been a] flight control system malfunction or failure. . ." A parachute valve is considered to be a flight control on a balloon. The pilot took the balloon to a repair station for repairs. The repair station owner was concerned with the mode of failure of the deflation line and, familiar with the above paragraph, notified the Denver NTSB Office and her FAA principal maintenance inspector. The deflation line was sent to NTSB's materials laboratory for examination. Report No. 99-216 noted there was 1. glazing damage to the outer cover, typical of heat damage; 2. unraveled and missing outer cover, exposing the Kevlar inner core; 3. longitudinal compression of the outer cover; 4. discoloration of the outer cover, ranging from light to severe; and 5. the fracture, exposing fraying and unwinding of the Kevlar inner core fiber bundle. Light discoloration of the deflation line is typical of normal use. Two areas of moderate and severe discoloration "showed no signs of heat damage. The discoloration did not extend completely around the circumference of the line." According to Balloon Works, the Kevlar braided inner core chars at 890 degrees F. The nylon or polyester braided outer covering has a stick point of 430 degrees F. and a melting point of 492 degrees F. A new line has a nominal strength of 4,000 pounds.