July 12 (Reuters) – A preliminary report into the Air India crash that killed 260 people last month showed three seconds after taking off, the plane’s engines fuel cutoff switches almost simultaneously flipped from run to cutoff, starving the engines of fuel.

The Boeing BA.N 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. “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 9,000 on the 787.

The preliminary report also does not say how the switch could have flipped to the cutoff position on the June 12 London-bound flight from the Indian city of Ahmedabad.

U.S. 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?”

U.S. 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 cutoff 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 cutoff.

“At this stage of investigation, there are no recommended actions to Boeing 787-8 and/or GE GE.N 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.

The agency, an office under India’s civil aviation ministry, is leading the probe into the world’s deadliest aviation accident in a decade.

The plane’s two black boxes, both combined cockpit voice recorders and flight data recorders, were recovered in the days following the crash and later downloaded in India.

Black boxes provide crucial data such as altitude, airspeed and final pilot conversations which help in narrowing down possible causes of the crash.

Most air crashes are caused by multiple factors, with a preliminary report due 30 days after the accident according to international rules, and a final report expected within a year.

Air India has been under intense scrutiny since the crash.

The European Union Aviation Safety Agency said it plans to investigate its budget airline, Air India Express, after Reuters reported the carrier did not follow a directive to change engine parts of an Airbus A320 in a timely manner and falsified records to show compliance.

India’s aviation watchdog has also warned Air India for breaching rules for flying three Airbus planes with overdue checks on escape slides and in June warned it about “serious violations” of pilot duty timings.

The U.S. National Transportation Safety Board declined to comment on the release of the report.

NTSB chair Jennifer Homendy had previously urged the Indian government to be transparent in the interest of aviation safety.

(Reporting by Hritam Mukherjee and Gursimran Kaur in Bengaluru and Aditya Kalra and Abhijith Ganapavaram in New Delhi; Additional reporting by Allison Lampert in Montreal, David Shepardson in Washington and Rajesh Kumar Singh in Chicago; Writing by Dan Catchpole; Editing by Jamie Freed)