Air India said on Tuesday it has completed precautionary inspections of the fuel control switch locking mechanism on all its Boeing 787 and 737 aircraft, with no issues detected. The probe into the Air India crash that killed 241 of the 242 people on board and 19 on the ground is focused on the fuel control switches of the Boeing 787 jetliner,

According to a report published on Wednesday by The Wall Street Journal quoting sources close to United States officials’ early assessment of evidence, the black box audio recording of the last conversation between the two pilots indicates that the captain might have turned off the switches controlling the flow of fuel to the plane’s engines.