WASHINGTON/SHANGHAI, May 6 (Reuters) - The U.S. National Transportation Safety Board released data this week indicating the fuel supply was switched off to both engines of a China Eastern Airlines Boeing 737 jet before the aircraft plunged into a hillside in southern China in March 2022, killing all 132 people on board.

The NTSB said on Wednesday its probe of China’s deadliest air disaster in three decades turned up no safety issues. Fuel switches on Boeing 737 aircraft are physical controls regulating fuel flow to the engines, and a pilot must pull the switch up before moving it from run to cutoff.

Its release is the first significant investigative update on the deadly crash.

In March, China’s aviation regulator opted for the second year not to release an annual update on its investigation of the crash, letting the fourth anniversary pass without providing any insight into the cause.

The data, released by the NTSB in response to a Freedom of Information request, originated from the plane’s flight data recorder. It showed fuel switches for both engines moved simultaneously from the run position to the cutoff position before the jet descended.