The Boeing 787 Dreamliner immediately began to lose thrust and sink down, according to the report released on Saturday by Indian aviation accident investigators.
One pilot can be heard on the cockpit voice recorder asking the other why he cut off the fuel.Â
"The other pilot responded that he did not do so," the report said.
It did not identify which remarks were made by the flight's captain and which by the first officer, nor which pilot transmitted "Mayday, Mayday, Mayday" just before the crash.
At the crash site, both fuel switches were found in the run position and the report said there had been indications of both engines relighting before the low-altitude crash.
Both pilots were experienced jet pilots with about 19,000 total flying hours between them, including more than 9000 on the 787.
The preliminary report also does not say how the switch could have flipped to the cut-off position on the June 12 London-bound flight from the Indian city of Ahmedabad.
US aviation safety expert Anthony Brickhouse said a key question is why were the switches moved in a way that is inconsistent with normal operations.
"Did they move on their own or did they move because of the pilots?" he asked. "And if they were moved because of a pilot, why?"
US aviation safety expert John Cox said a pilot would not be able to accidentally move the fuel switches that feed the engines. "You can't bump them and they move," he said.
Flipping to cut-off almost immediately cuts the engines. It is most often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report does not indicate there was any emergency requiring an engine cut-off.
"At this stage of investigation, there are no recommended actions to Boeing 787-8 and/or GE GEnx-1B engine operators and manufacturers" India's Aircraft Accident Investigation Bureau said.
Air India, Boeing and GE Aerospace did not respond immediately to requests for comment.
