Boeing firefighters voted on Thursday to approve a new four-year contract deal that will boost wages for workers and end a weeks-long lockout by the planemaker.

Boeing in early May locked out members of the International Association of Fire Fighters (IAFF) Local I-66 in Washington state after they rejected two contract offers, in a move that drew the concern of President Joe Biden, Washington state Governor Jay Inslee and many members of Congress.

Unionized firefighters voted 86-24 to approve the deal and firefighters will return to work on Saturday.

The four-year deal includes general wage hikes of 2% to 3% annually, with guaranteed overtime increasing annual pay on average by up to $21,216, as well as a $1,000 signing bonus and other compensation improvements, according to a joint fact sheet from the company and the union reviewed by Reuters.

The deal also includes job classification restructuring that allows more opportunities for promotion and will significantly reduce the time needed to get to top pay.

Boeing said on Thursday it is "pleased our firefighters have ratified a new contract and looks forward to them returning to work."

It did not disclose the additional financial burden on the company from the deal and did not respond to a question on that.

The company said in early May it had offered to increase firefighters' average take-home pay to $112,000 in the first year from $91,000.

The International Association of Machinists and Aerospace Workers is separately negotiating a new contract on behalf of more than 30,000 workers who build Boeing's 737 MAX jets.

IAFF I-66 President Casey Yeager said in an interview that those larger talks was a factor in the difficult talks with Boeing. "Did Boeing really want to give into a 125-person local when they have 30,000 people coming up in the fall," he said.

Yeager added the deal brings wages for firefighters "into comparable range" of fire departments in the area.

Boeing 737 MAX production has fallen sharply as the Federal Aviation Administration steps up factory checks following a panel blowout on a new Alaska Airlines 737 MAX 9 in January, blamed on an assembly error. Boeing met with the FAA on Thursday to discuss its 90-day plan to boost quality.

(Reporting by David Shepardson; Editing by Muralikumar Anantharaman)