The Directorate General of Civil Aviation on Monday told all domestic airlines operating Boeing aircraft to inspect key fuel control switch mechanisms on their fleets by July 21, CNBC-TV 18 reported.

“Strict adherence to the timeline is essential to ensure continued airworthiness and safety of operations,” the aviation regulator said in its directive.

This comes two days after the Aircraft Accident Investigation Bureau released a preliminary report on the June 12 Ahmedabad plane crash.

The crash, which killed 275 persons, is said to be the world’s worst aviation disaster in a decade.

In its report, the bureau found that moments after the aircraft took off, its fuel control switches transitioned from “RUN” to “CUTOFF” within a second of each other, because of which both engines shut down.

The report said that one of the pilots could be heard on the cockpit voice recorder asking the other why he shut down the fuel, in response to which the other pilot said that he did not.

After a gap of about 10 seconds, the switches went back to the “RUN” position, in what appeared to be an attempt by the pilots to regain thrust in the engines. Subsequently, one of the engines progressed to recovery and deceleration stopped. But deceleration could not be stopped on the second engine.

The flight lasted for about 30 seconds from the lift-off to the crash, said the report.

In its directive on Monday, the Directorate General of Civil Aviation cited a 2018 advisory from the United States Federal Aviation Administration, which had warned of potential fuel switch malfunctions in certain Boeing aircraft models.

Abu Dhabi-based Etihad Airways had issued a similar internal directive on Saturday, instructing its pilots to “exercise caution” while operating the fuel control switches on Boeing 787 aircraft, The Hindu reported. The airline also called for an inspection of the locking mechanisms on the switches.

Etihad also advised crew members against placing any objects on the pedestal that could inadvertently shift the fuel control switches.

No mechanical problems with aircraft: Air India CEO

The preliminary report released by the Aircraft Accident Investigation Bureau on the Ahmedabad plane crash did not find any mechanical or maintenance problems with the Boeing aircraft or its engines, The Hindu quoted Air India Chief Executive Officer Campbell Wilson as saying.

In an internal communication to Air India employees, Wilson said that every Boeing 787 aircraft in the airline’s fleet was checked within days of the June 12 crash and all were found fit for service.

“We continue to perform all necessary checks, as we will any new ones that authorities may suggest,” the newspaper quoted him as saying.

Wilson added that the report “provided both greater clarity” and “opened additional questions”.

He also advised employees not to focus on the “ongoing cycle of theories, allegations, rumours and sensational headlines”.

“I urge everyone to avoid drawing premature conclusions as the investigation is far from over,” he said.

He assured that the airline would cooperate with the investigation process to ensure a “thorough and comprehensive enquiry”, The Indian Express reported.

Wilson added that there was “no issue with the quality of fuel and no abnormality with the take-off roll” and that the “pilots had passed their mandatory pre-flight breathalyser and there were no observations pertaining to their medical status”.

Air India’s top priorities continue to be “standing by the bereaved and those injured, working together as a team, and delivering a safe and reliable air travel experience to our customers around the world”, he said.

On June 12, Air India’s Boeing 787-8 Dreamliner aircraft, which was en route to London’s Gatwick airport from Ahmedabad, crashed just 33 seconds after taking off.

There were 242 people aboard the aircraft. One passenger survived with “impact injuries”.

Thirty-four persons were also killed on the ground after the plane crashed into the hostel building of the BJ Medical College and Hospital in Ahmedabad, according to Air India.