The US Justice Department has reportedly subpoenaed Boeing for records on the production of the 787 Dreamliner, signaling an expansion of its Boeing 737 Max criminal investigation to the airline's larger, luxury aircraft. Citing two sources, the Seattle Times on Friday said there have been "allegations of shoddy work" and corner-cutting on Dreamliner production in South Carolina.

Boeing's 737 Max MCAS flight control system was blamed as the cause of two crashes in Indonesia and Ethiopia that killed 346 people. Boeing completed test flights for the software fix to its grounded 737 Max airliner in April, and in May said the update was finished and ready for evaluation by the Federal Aviation Administration.

According to the Seattle Times, a third source said several Boeing employees were subpoenaed on the Dreamliner production plant in North Charleston, South Carolina, earlier in June. These subpoenas came from the same DOJ prosecutors involved in the 737 Max investigation, the report said.

The DOJ is looking into "broad cultural problems" at Boeing, the Seattle Times said a source suggested.

There's still no schedule for when the 737 Max will be back in the air, but earlier this month Boeing scored a deal with International Airlines Group -- including British Airways, Aer Lingus, Iberia and Vueling -- which will buy 200 737 Max 8s and 10s.

Both the DOJ and Boeing declined to comment.

First published at 3:45 p.m. PT on June 28.
Updated at 5:25 p.m. PT: adds both DOJ and Boeing declining to comment