Boeing 737 MAX airplanes are stored in an area adjacent to Boeing Field, on June 27, 2019 in Seattle, Washington. After a pair of crashes, the 737 MAX has been grounded by the FAA and other aviation agencies since March, 13, 2019. The FAA has reportedly found a new potential flaw in the Boeing 737 Max software update that was designed to improve safety.

Boeing on Tuesday again reported no new orders for its 737 Max, as the worldwide grounding of its best-selling plane is about to enter its fifth month, dragging down aircraft deliveries.

Boeing delivered 239 commercial airplanes in the first half of the year, down 37% from the first six months of 2018. Deliveries are key for the company since that is generally when the manufacturer is paid for the aircraft.

The dearth of Max orders in June marked the third straight month without any new orders for the planes. The issues could give European manufacturer Airbus, which reported 389 commercial plane deliveries in the first six months of the year, the crown as the world's biggest airplane maker. Airbus' popular A320 planes compete with Boeing's 737s in the single-aisle segment, which comprise most aircraft orders.

The Boeing 737 Max planes have been grounded since mid-March after two fatal crashes that claimed a total of 346 lives. Investigators found similarities between the two crashes and implicated an anti-stall system in both deadly incidents. Boeing has prepared software fixes for the planes but regulators have not said when they will permit the planes to fly again, prompting carriers to cancel thousands of flights. Both airlines and Boeing have been force to park the grounded jets.

Boeing cut production of the 737 Max by about a fifth to 42 jetliners a month in April. It had originally expected to ramp up production to 57 a month. The Chicago-based company has a backlog of about 4,600 737 jets.

Last month, Boeing won a vote of confidence in the troubled 737 Max when British Airways' parent International Consolidated Airlines Group, said it plans to buy 200 of the jets. Boeing didn't include the orders in its monthly tally because the order isn't finalized. Over the weekend, flyadeal, a budget airline based in Saudi Arabia, canceled a provisional order for 30 Boeing 737 Max planes, and said it would take delivery of A320 jets from Airbus instead.

Boeing's shares initially fell after the manufacturer reported its quarterly orders and deliveries, but closed up 0.6% at $353.09.