A historic locomotive now under repair at Railtown 1897 State Historic Park should be in operation by next summer.

Railtown's Sierra No. 28, originally purchased from Philadelphia's Baldwin Locomotive Works in 1922, has been out of service since 2009. Several skilled volunteers and professional staff have been working on much-needed repairs during the past two months.

"We're actually doing major surgery on the locomotive," said volunteer Greg Petersen, who works as part-time fire chief of the Angels Camp Fire Department.

Petersen spends most Thursdays volunteering at Railtown doing blacksmithing and locomotive repair. The 68-year-old spent this week working on the locomotive's "fire box."

"That's where the fire burns that creates the steam that allows the engine to run," he said.

Visitors to the park can now get a rare look at the stripped-down locomotive. Repairs include replacing corroded parts and fixing the boiler in addition to completing an inspection that is required every 15 years by the Federal Railroad Administration.

"They have an opportunity to see what the locomotive looks like as it's being built," Petersen said of Railtown visitors.

A "behind the scenes" shop tour of work being done on the No. 28 is held at 10 a.m. every Tuesday.

The goal is to have the No. 28 running by next summer to carry passengers on weekend train rides, said park Superintendent Kim Baker.

"It really is a critical resource for us," she said.

The repairs are a boost for Railtown, which was on a state park's closure list just last year.

Baker said the No. 28 will increase Railtown's ability to make money.

"We will be able to pull more passengers and generate more revenue at special events," she said.

The total cost to repair the No. 28 is $231,000. That money comes from $75,000 raised by five Tuolumne County Rotary clubs and a matching $75,000 from the Sonora Area Foundation. Sacramento-based California State Railroad Museum Foundation, Railtown's nonprofit partner, contributed the remaining $81,000.

California State Parks has agreed to match that amount with an additional $231,000, which Railtown plans on spending on operating expenses and developing an "interpretive master plan," among other projects.

Railtown will continue its weekend train rides throughout October in addition to holiday-themed rides in November and December.