The two engines on the Air India flight shut down within one second of each other before the Boeing 787 Dreamliner crashed last month in Ahmedabad, India, killing at least 260 people, according to a preliminary report released Friday.

There are some safety measures that are mandated because they’re considered essential to flight safety that’s why they’re issued as airworthiness directives.

Indian investigators determined the Boeing 787 Dreamliner was properly configured and lifted off normally. But three seconds after takeoff, the engines' fuel switches were cut off.