THE STATE'S biggest fire-fighting weapon returned to the Ballarat district for another test run yesterday. A modified DC-10 aircraft dumped a 42,000-litre load of fire retardant at the Enfield State Forest. The drop was made in part of the forest where a controlled burn was being done.Researchers from the Bushfire Co-operative Research Centre were looking at how effective the dump was at restricting fire from a controlled burn. Country Fire Authority operations manager Stephen Walls said the morning's drop had gone as planned."What we're trying to do is see if these very large air tankers are suitable for Australian conditions," he said.Ideally, the best way to find that out would be to see how it performed in heat, wind and often rugged terrain in a bushfire.But mild conditions over most of this summer have meant it has only been deployed once, for a Wimmera scrub fire.Yesterday's test run followed a similar exercise at the Wombat State Forest in January.Department of Sustainability and Environment chief fire officer Ewan Waller said the aircraft's capabilities would continue until it flies out of Victoria later this month.Large plumes of smoke from the 413 hectare Enfield controlled burn were visible from Ballarat.The DSE will continue burns across the region today, at Anderson's Mill near Smeaton; Spencer St and Bakers Rd in Canadian; and Shepherd Gully Track near Beaufort.Providing weather and operating conditions are suitable, the burns will begin early this morning.For more information on burns and fires in Victoria and general fire safety advice, call the Victorian Bushfire Information Line on 1800 240 667.