A tail of an Air India Boeing 787 Dreamliner plane that crashed is seen stuck on a building after the incident in Ahmedabad, India, June 12, 2025. REUTERS/Amit Dave

The GE Aerospace-made engines have been at the centre of the probe into the crash of the Air India plane shortly after takeoff from Ahmedabad on June 12, 2025, which killed 260 people in the world’s deadliest air disaster in a decade.

A preliminary report released last year showed the 787’s engine fuel control switches moved almost simultaneously from “RUN” to “CUTOFF,” starving both engines of fuel shortly after the flight took off.

Investigators conducted engine testing in April and visited France last month as part of ⁠an analysis of the engine management unit, the source told Reuters on the condition of anonymity because the information is not public.

Burnt vehicles at the site where an Air India Boeing 787-8 Dreamliner plane crashed on June 12, 2025, during takeoff from a nearby airport, in Ahmedabad, India, June 10, 2026. REUTERS/Amit Dave

Earlier on Thursday, Bloomberg News reported the final report into the crash was expected within three months once studies of the engines, which had been sent to the U.S. for examination, were concluded.

Under international rules, a final report is due “if possible” within a year of an accident, but sometimes investigations take longer, so if that is not completed, an interim statement should be issued on each anniversary.

Suresh Patni, father of Akash Patni, 14, who died in an Air India Boeing 787-8 Dreamliner plane crash incident on June 12, 2025, during take-off from an airport, mourns near the plane crash site in Ahmedabad, India, June 10, 2026. REUTERS/Amit Dave

Reuters first reported last month that Indian officials were preparing an interim report rather than a final one ahead of the first anniversary because the investigation was deemed complex and time-consuming. At that time, a source told Reuters the timing of the final report had not been decided yet.

The release of an interim report has been opposed in some quarters, notably by the Federation of Indian Pilots union. The union has previously pushed for investigators to seek more technical data on the plane from Boeing and Air India to allow for a “rebuttal of the pilot suicide theory being explored ‌by the AAIB”.

Damaged buildings at the site of an Air India Boeing 787-8 Dreamliner plane that crashed on June 12, 2025, during takeoff from a nearby airport, in Ahmedabad, India, June 10, 2026. REUTERS/Amit Dave

“It ⁠will cause more speculation and more misunderstanding,” CS Randhawa, the union’s president, told reporters at a packed press conference in Ahmedabad ahead of the anniversary of the crash.

“We have requested the Indian government and India’s Aircraft Accident Investigation Bureau (AAIB) not to come out with any interim report.”

The AAIB, India’s aviation ministry, Air India, the U.S. National Transportation Safety Board, Boeing and GE Aerospace did not immediately respond to Reuters’ requests for comment.

Pilot actions examined

A cockpit recording of dialogue between the two pilots of the Air India 787 before it crashed supported the view that the captain cut the flow of fuel to its ⁠engines, according to U.S. officials’ early assessment reported by Reuters last year.

The AAIB said at the time it was “too early to reach any definite conclusions.”

The father of the captain asked India’s top court to order an independent investigation that took into account causes other than deliberate pilot action, which has been suspected in some other fatal crashes and confirmed in the case of Germanwings in 2015.

People stand in front of damaged buildings at the site where an Air India Boeing 787-8 Dreamliner plane crashed on June 12, 2025, during takeoff from a nearby airport, in Ahmedabad, India, June 10, 2026. REUTERS/Amit Dave

The preliminary report did ⁠not make any safety recommendations to Boeing or GE, indicating no technical issues had been discovered at that time.

It was the world’s first crash involving a 787 Dreamliner, a Boeing model that has been in service since 2011.

The crash also hit Air India at a sensitive stage of its post-privatisation turnaround, which has been slowed by supply-chain snags, an airspace ban imposed by ⁠Pakistan on Indian carriers and more recently, the U.S.-Israeli war on Iran.