TAMPA — United Airlines is starting construction on a $33 million maintenance hangar at Tampa International Airport where about 100 mechanics and skilled technicians will do work that should relieve congestion at some of United's bigger hubs.

In February, the Hillsborough County Aviation Authority voted to lease United 9.5 acres east of Tampa International's terminal and airfield as a site for a three-bay maintenance hangar and tarmac for its Boeing 737 and 757 jets.

"We knew at that time this would be a great deal," aviation authority chairman Robert Watkins said at a ceremony Wednesday to mark the start of construction. He also said the new facility will complement the airport's $2 billion master plan that includes more curbside space, more commercial development and a new airside to accommodate future growth. "This United hangar will fit right in with our plan of bringing more flights, more residents, more jobs and more economic impact to our community."

United will start paying rent two years after the agreement was approved, whenever its new hangar is finished or as soon as it starts to use the property for its operations, whichever comes first. The rent will be $297,950 during the first year of the 20-year agreement, then rise in line with consumer price index. The airline will get a rent credit of about $1.2 million for doing site preparation work that normally would be the responsibility of the airport.

Details about potential economic development incentives for the hangar project were not available Wednesday from the Tampa Hillsborough Economic Development Corp., which can mean that the state and local decision-making process regarding an application for incentives is not complete and that details of any potential incentives are exempt from disclosure under Florida's public records law.

The airport and airline have been talking about building a new maintenance hangar for four years. Each week, United has 277 flights serving six markets into or out of Tampa International.

United vice president of maintenance operations Don Wright said United chose Tampa for the expansion because "Tampa's a great place to do business," because the airport made a compelling case for the facility and because the bay area's quality of life and relatively low cost of living should make it easier to recruit employees internally, from aviation schools and from retiring military technicians.

When it opens in the spring of 2020, the hangar will include about 66,000 square feet of hangar space and 17,620 square feet of office and shop space, or 75 percent more warehouse area than United's mechanics have now. It is expected to bring more aircraft maintenance work into Tampa, helping to relieve congestion at the airline's hubs.

"This will improve our efficiency with the United system and we will no longer conduct heavier aircraft maintenance checks on the overnight aircraft at the gate," said Dan Sonego, United's senior manager of aircraft maintenance in Tampa.

Wednesday's event comes a day before United is scheduled to double its daily service between Tampa and San Francisco to twice a day. That expansion will start this month and allow business fliers to get to San Francisco for an afternoon meeting or dinner and return to Tampa on the new red-eye flight.

'MORE CHOICE': Another United Airlines' Tampa-to-San Francisco flight opens possibilities for business travelers and those heading to Asia

United's nonstop flights to San Francisco began in February 2017 and effectively "connected us to the grid," Tampa International Airport chief executive officer Joe Lopano said.

"If you're not connected to San Francisco and Silicon Valley, you're not connected to the grid," he said. "It's done great things for our high-tech community."

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Contact Richard Danielson at rdanielson@tampabay.com or (813) 226-3403. Follow @Danielson_Times