(Bloomberg) -- Boeing Co. delivered 24 commercial jets in May, including 19 of its 737 family aircraft, as parts shortages and fresh scrutiny by China’s regulators complicated efforts to recover from a crisis engulfing its most popular aircraft.

While rival Airbus SE handed over 53 aircraft last month, the U.S. planemaker matched its total for April, the lowest monthly tally in more than two years. Boeing also recorded four gross jet orders against one cancellation for the month. 

Boeing has pared back deliveries of its cash cow 737 jets as it slows down work, increases inspections at supplier Spirit AeroSystems Holdings Inc., and seeks to reinforce safety at its factories in the wake of a near-catastrophic accident in January. The manufacturer expects to burn through about $8 billion in cash during the first half of the year, with the financial strain set to ease in the latter part of the year as deliveries pick up again.

The company’s shares slid 3.2 per cent at 1:25 p.m. in New York as investors digested the results and news of another potential salvo in the US-China trade war. Boeing’s stock has dropped roughly 30 per cent this year.

It’s unclear whether Boeing will benefit from the customary rally in aerospace shares ahead of the industry’s main trade event next month, which typically yields a bumper crop in orders, said RBC Capital Markets analyst Ken Herbert. “For investors, we believe the focus remains on aircraft production rates” and paring Boeing’s inventory of already built planes, he said in a note to clients on Tuesday.

By one measure, the campaign to improve quality appears to have shown modest improvements in May. Of the 737 Max deliveries, 16 aircraft were recent factory rollouts, up from just nine jets in April, Scott Deuschle, analyst with Deutsche Bank, said in a June 3 report. Boeing declined to say how many deliveries were of factory-fresh aircraft versus those coming out of long-term storage.

Boeing shipped five widebody aircraft in May, including two 787 Dreamliners. While one of the carbon-composite aircraft went to China, its delivery paperwork was completed in early May. That’s before the nation’s regulators paused imports from the US planemaker over the design of new, 25-hour cockpit voice recorders that have been approved by their counterparts in the U.S. and Europe. The delivery halt remains in effect, Boeing said.

Through the end of May, Boeing has delivered 131 airplanes, including 102 of its 737 family models. Airbus’s total stands at 256 units. However, 787 deliveries fell by half versus April as the company grappled with shortages of heat exchangers and premium seats. Boeing didn’t deliver any 777 freighters, either, and has only handed over two of the models so far this year.

Investors need to see “accelerating improvement” in deliveries of all three aircraft to gain confidence that Boeing’s cash outflows will turn around during the second half, Deuschle said.