Boeing is facing fresh concerns about the safety of its troubled Max 737 jet.

The Boeing 737 Max made its first commercial flight in 2017. In less than two years, it was grounded worldwide after a pair of crashes abroad killed 346 people.

Boeing admits the plane had software problems, but says they are now being fixed. It hopes to have the Max back in the air this spring.

Some advocates aren't sure that's a good idea.

"Our No. 1 question that we’re getting from flyers is, 'How do I avoid that bad plane?'" says Paul Hudson, president of the organization Flyers' Rights.

Hudson's group recently sued the FAA, asking the agency to publicly release documents that detail the changes Boeing plans to make.

This week, Boeing says it uncovered another issue with the 737 Max -- a potential wiring problem that could cause short circuits. But the company is still optimistic it will get approval to un-ground the plane. In fact, some airlines have penciled it back on the schedule for as early as April.

But the FAA will have the final say, and the agency says it has no timeframe for the 737 Max to return. It says the plane will only be allowed to fly if it can meet all safety standards.

This week, Boeing released memos that showed employees joking about serious flaws in the 737 Max.