On June 16, 1996, approximately 0615 Pacific daylight time, a Firefly 8B hot air balloon, N71233, registered to and being flown by a commercial pilot, was substantially damaged when it collided with the static line above 230,000 volt high tension power lines near Wilsonville, Oregon. The pilot and one occupant sustained serious injuries while the remaining two occupants sustained minor injuries. Visual meteorological conditions existed at the time and no flight plan had been filed. The flight, which was a personal entrant into a balloon race, was to have been operated under 14CFR91, and originated from an open field several miles from the crash site. The pilot reported that after aborting a landing attempt due to overflying the field, he selected another field further downwind. He observed high tension lines and maneuvered to clear them but "never saw (the) 3/8" cable above." After the balloon contacted the static wire, it broke and the pilot observed electrical arcing as the line contacted the high voltage lines beneath. The balloons envelope caught fire, however, the pilot was able to land the balloon without igniting any of the propane bottles. The pilot also reported that "there was a high overcast" and that he "didn't see the small, grey wire until contact against (the) grey sky."