Investigators believe the Air India Boeing Dreamliner had its emergency-power generator operating when it crashed last week in India's Ahmedabad, the Wall Street Journal reported on Wednesday citing people familiar with the probe.
Boeing said it will defer to India's Aircraft Accident Investigation Bureau for comment. Engine maker GE Aerospace did not respond to a Reuters request for comment.
India's federal civil aviation ministry did not immediately respond to Reuters' email seeking comment.
Reuters couldn't immediately verify the WSJ report.
The system, known as the Ram Air Turbine (RAT), generates electricity and hydraulic pressure to ensure pilots can control the plane even if both engines fail.
The preliminary finding raise questions about whether the plane's engines functioned properly during takeoff, the report said. The Dreamliner was fitted with GE Aerospace's GEnx engines.
The Boeing 787-8 Dreamliner carrying 242 people bound for Britain's Gatwick Airport began losing altitude seconds after takeoff. All but one passenger died in the world's worst aviation disaster in a decade, with around 30 ground fatalities.
India's aviation safety watchdog said on Tuesday that surveillance of Air India's Boeing 787 fleet revealed no major safety concerns.