(Reuters) -Boeing will burn rather than generate cash in 2024 and deliveries will not increase in the second quarter, the company's finance chief said Thursday, as the U.S. planemaker grapples with a full-blown crisis that is pinching production of its strongest-selling aircraft.

CFO Brian West told the Wolfe Research Global Transportation and Industrials Conference that he expects Boeing's full-year free cash flow to be negative, compared with March's outlook for positive cash generation in the low single-digit billions.

His remarks surprised some investors, sending shares down 6% in midday trade and deepening the company's problems as production challenges and delayed deliveries to China reversed a rosier 2024 outlook upheld by Boeing just weeks earlier.

"How did things change so quickly?" said one portfolio manager who holds Boeing stock on condition of anonymity.

Boeing's jet production has slowed dramatically in the face of increased scrutiny from regulators, airlines and lawmakers following a January incident when a door plug blew off an Alaska Airlines jetliner while in mid-air.

West confirmed a Wednesday Reuters report that said plane deliveries to China were delayed in recent weeks due to a Chinese regulatory review of batteries powering the cockpit voice recorder. The delay will have an effect on free cash in the second quarter.

The U.S. planemaker said in a statement on Wednesday it is working with Chinese customers on the timing of their deliveries as the Civil Aviation Administration of China completes its review of batteries contained within the 25-hour cockpit voice recorder.

Commercial jet deliveries won't step up in the second quarter compared with the first three months of the year, West said, adding that "we have frustrated and disappointed" customers due to the supply chain and production issues.

"If you're on the inside you're seeing progress," West said, but also said "everyone wishes it would go faster."

Coming into the day's trading, Boeing stock was down 30% this year.

Boeing 737 MAX jetliner production fell as low as single digits in April, Reuters reported, well below the U.S. Federal Aviation Administration cap of 38 jets a month as workers slow the assembly line outside Seattle to complete outstanding work.

The Alaska Airlines incident, which occurred on a new jetliner, prompted U.S. aviation regulators to curb the company's production levels until Boeing starts to address safety issues. The company is overhauling its manufacturing practices and it is also searching for a new chief executive after current CEO Dave Calhoun agreed to leave by year-end.

Top U.S. enforcement officials are also weighing whether to charge the company for violating an agreement that shielded it from prosecution stemming from previous jet crashes in 2018 and 2019.

The FAA has imposed a May 30th deadline for the planemaker to hand over a 90-day report that would address "systemic quality-control issues." FAA Administrator Mike Whitaker said Thursday that Boeing faces a "long road" to address safety issues.

Separately, the U.S. Justice Department intends to decide by July 7 whether to prosecute Boeing after determining the planemaker breached its obligations in a 2021 agreement that shielded it from criminal prosecution over fatal 737 MAX crashes in 2018 and 2019.

Boeing is currently in negotiations to acquire 737 MAX fuselage supplier Spirit AeroSystems. West said a Spirit deal is possible in the second quarter, but the deal is large and complex, and should not be rushed.

Boeing spun off Spirit in 2005, and the company now derives a portion of its revenue from Boeing rival Airbus, which wants compensation for taking on some of Spirit's operations.