AFTER 12 months on the sidelines under repair, the Southern Downs Steam Railway engine No971 is back on the main line.

Yesterday morning, under the watchful eye of fitters John Brady and Dave Laker, the engine made 20 runs up and back down the lines in the Warwick Railway Precinct.

Southern Downs Steam Railway secretary Bob Amos said the engine had a dry run on Thursday.

"We had a shunt engine tow the loco around the yard just to check all the moving parts were working as they should and then yesterday we fired her up and went under steam power for the first time in a year," he said.

"We're very pleased that everything is working exactly as it should.

"On Saturday we'll do a test run out to Hendon and, hopefully, all will be well for our first passenger trip next Saturday."

The reason the locomotive has been out of action for so long was due to wear and tear on the pistons and valves and Mr Amos said this meant they were leaking steam.

"Which, in turn, meant a lack of power to drive the wheels," he said.

"So we had to repair them all.

"We took everything apart and removed the pistons and valves.

"These had to be re-machined and we had to have new piston rings manufactured, then everything had to be reassembled."

Mr Amos said huge thanks were owed to GJ Engineering, in Warwick, and Ian Batham for their assistance and also to the Queensland Rail.

"We need to thank the Ipswich workshop for their help and also the heritage division for loaning us a sister locomotive so we could continue to take passengers on trips through our beautiful region," he said.

The refurbished steam train will run from Warwick to Wallangarra on Saturday, November 26, departing Warwick at 8am and returning to Warwick at 5.45pm.