NEW DELHI, India: British aviation regulators are seeking answers from Air India after a Boeing 787 Dreamliner departed London despite a suspected issue with a fuel control switch, raising fresh safety questions around the airline's widebody fleet.

Britain's Civil Aviation Authority (CAA) has asked Air India to explain how the aircraft took off from London last Sunday before being grounded on arrival in India for checks, according to a letter seen by Reuters. The regulator warned that it could take action against Air India and its Boeing 787 fleet if it does not provide a full response within a week.

Air India said it has completed a precautionary re-inspection of the fuel switches and found no problems, adding that it would "respond to the UK regulator accordingly".

The CAA said in a statement that requesting such information was routine. It said it was a standard process for a regulator to seek details following "an aircraft incident and is in line with safety assurance procedures".

Fuel control switches have drawn heightened attention since last year's crash involving an Air India Dreamliner in Gujarat state, which killed 260 people and led to increased scrutiny of the airline. The switches regulate the flow of jet fuel into an aircraft's engines. Air India said that it had grounded a Boeing Dreamliner after a pilot reported a possible "defect" with the fuel control switch upon landing in India.

Boeing, which had earlier said it was cooperating with Air India on the matter, did not respond to a request for comment.

UK Regulator Seeks ‘Detailed' Account

India's civil aviation watchdog later said that during engine start procedures in London, the flight crew observed that the fuel control switch did not remain latched in the ‘run' position on two occasions, but appeared stable on a third attempt.

The crew then decided to continue the flight to India. Subsequent checks by Indian regulators found the switches to be functioning normally.

The UK CAA, however, told Air India it must provide "a detailed account of all maintenance actions performed to ensure the continued airworthiness of the aircraft and to support its release to service for Bengaluru, according to the letter, which was not made public.

Root Cause Analysis Sought

The British regulator also requested a "comprehensive root-cause analysis" of the incident and a "preventive action plan" to ensure similar events do not recur across Air India's Boeing 787 fleet.

In an internal memo circulated on February 4, Air India said it had checked the fuel switches on all of its Boeing 787 aircraft — which aviation tracking site Flightradar24 says total 33 — and that "no issues were found".

The airline has faced closer regulatory oversight following last year's fatal crash, and the latest incident adds to scrutiny of maintenance procedures and decision-making involving safety-related components.