Air Illinois

Avro 748

Flight 710 departed Chicago, IL for a flight to Carbondale, IL via Springfield, IL. The flight was about 45 minutes behind schedule when it arrived at Springfield, about 20:05. At 20:11, the flightcrew were provided with the latest Carbondale weather: ceiling and visibility were 2,000 feet overcast and 2 miles, respectively, with light rain and fog. The crew then requested its IFR clearance, with 5,000 feet for its en route altitude. At 20:16, Flight 710 was cleared to taxi to runway 15 for takeoff. The aircraft took off at 20:20 and climbed to cruising altitude. At 20:21:34, Flight 710 informed the departure controller that it had experienced a "slight electrical problem..." and that it would keep the controller "advised." The flight then requested and was cleared to maintain 3,000 feet. At 20:23:54, the first officer told the captain that "the left (generator) is totally dead, the right (generator) is putting out voltage but I can't get a load on it." At 20:24:26, the first officer reported, "zero voltage and amps (amperes) on the left side, the right (generator) is putting out twenty-seven and a half (volts) but I can't get it to come on the line." The battery voltage further dropped to 22 volts. The crew a.o. shut off excess cabin lights because of the electrical problem. About 20:38, the first officer mistakenly isolated the right generator and right generator bus bar from the aircraft's dc electrical distribution system. Radio contact was lost when the flight was requested to change radio frequencies. At 20:52 the captain decided to descend to 2,400 feet and the voltage had further dropped to 13 volts. The aircraft continued to descend and struck the ground in an open pasture area.