New York (CNN Business) Boeing reported no new commercial aircraft orders in May. It was the second straight month that Boeing's orders were at a standstill in the face of the 737 Max crisis.

The drop in orders isn't only because of the grounding of the 737 Max . Boeing also has a massive backorder of about 5,000 planes. Many of its customers do not need to place orders for additional jets right now.

Next week is also the Paris Air Show, the key industry trade show for the year, at which Boeing and rival Airbus typically like to announce orders. So May is often a slower month for new orders.

Yet Boeing booked orders for 43 jets in May of 2018, ahead of that year's Paris Air Show. And 21 of those orders were for the 737 Max.

The 737 Max was grounded in mid-March after the second fatal crash of one of the planes in Ethiopia. Boeing is trying to win federal approval for a fix of an automatic safety feature which has been the focus of the crash investigations.

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