Boeing acknowledged Saturday it had to correct defects in its flight simulator software used to train pilots to fly the 737 MAX, the aircraft model involved in two deadly crashes that killed 346 people.

“Boeing has made corrections to the 737 MAX simulator software and has provided additional information to devise operators to ensure that the simulator experience is representative across different flight conditions,” the company said in a statement.

“These changes will improve the simulation of force loads on the manual trim wheel. Boeing is working closely with the device manufacturers and regulators on these changes and improvements, and to ensure that customer training is not disrupted.