By Shivansh Tiwary

(Reuters) - Boeing ( BA ) could lose over $100 million in daily revenue until it reaches a settlement with its union that represents more than 30,000 workers, analysts said on Monday.

The Seattle-area Boeing ( BA ) workers who build the planemaker's most popular 737 MAX and other jets in factories on the U.S. West Coast went on strike after rejecting their first full contract in 16 years last week.

A prolonged strike could cost several billion dollars, fraying the planemaker's already strained finances and threatening a downgrade of its credit rating.

The strike, Boeing's ( BA ) first since 2008, is the latest event in a tumultuous year for the company that began with a January incident when a door panel detached from a new 737 MAX jet mid-air. Shares have lost roughly 40% in value so far this year.

Northcoast Research estimates the total impact of the strike could reach $3 billion or more. "Boeing ( BA ) will most likely remove 33-35 jets from the original production plan, resulting in a loss of $102 million in daily revenue," said Chris Olin, an analyst at Northcoast Research.

New CEO Kelly Ortberg is now confronting a labor-management battle just weeks after he was brought in to restore faith in the planemaker, which is also facing heavy scrutiny from U.S. regulators for its safety practices.

Last week all three major ratings agencies warned that a prolonged strike could cost the company its investment-grade rating. That would increase borrowing costs for Boeing ( BA ), which already has a $60-billion debt pile.

"We estimate the strike will pare sales by more than 2008's nearly $100 million per day since current volumes are higher," TD Cowen analyst Cai von Rumohr said.

Boeing's ( BA ) finances are already under pressure due to negative free cash flow and poor margins. The planemaker needs to generate sufficient cash flow to meet payments on its debt.

On Monday, Boeing ( BA ) said it was freezing hiring and weighing temporary furloughs to keep costs in check.

Each revenue slip of more than $100 million per day will pare $60 million in cash, since the planemaker receives 60% of a plane's price upon delivery, TD's von Rumohr said.

Jefferies analysts say the strike would amount to a hit of about $1.3 billion in monthly free cash flow.