Air India has found no fault with the fuel switches of its Boeing fleet, the airline said on Tuesday, adding to mounting evidence that the pilots killed in the crash were to blame.

An investigation into a deadly crash last month has focused on control switches that cut off fuel to an Air India Boeing jet after takeoff.

Air India said Tuesday that it had completed precautionary inspections on the locking mechanism of fuel control switches for select Boeing aircrafts, with “no issues” found. The announcement came days after a preliminary investigation into last month’s Air India plane crash stated that the switches shifted and flipped within