Boeing’s 737 Max will be recertified to fly in Europe next week, according to the bloc’s aviation safety watchdog, but in future US-built aircraft will be subject to closer scrutiny from the EU Aviation Safety Agency.

Patrick Ky, executive director of Easa, said the relationship between the European regulator and its US peer, the Federal Aviation Administration, had changed for good after revelations of lax oversight in the development of Boeing’s newest single-aisle aircraft.

Easa would now assess independently which elements were safety-critical on US aircraft and components.

“We were not doing that . . . enough on US projects,” Mr Ky said at a press conference at a joint event held by Easa and the German Aviation Press Club. “We will do that more from now. We will make our own assessment and increase our level of involvement on those systems.”

The globally recognised system for aircraft certification has allowed manufacturers to self-certify certain elements of their programmes under the eye of local safety regulators.

However, the FAA has come under heavy fire at home and abroad for its weak scrutiny of Boeing during the development of the 737 Max, which was grounded for almost two years after two accidents in which 346 people died.

A US congressional subcommittee report into the accidents published last year found “grossly insufficient oversight by the FAA — the pernicious result of regulatory capture”.

The lesson had been taken on by global regulators. “The way we are doing things, especially in the certification world, will never be completely the same,” he said.

Mr Ky said the certification of Boeing’s next new aircraft, the 777X wide-body had raised “a number of questions on the relationship between the FAA and Easa and the way we conduct our own certification projects”.

The more stringent scrutiny could result in longer delays to certification, he suggested, at least while “a new way of working” bedded in. However, he insisted that since the accidents there had been “full transparency from Boeing and the FAA. We worked very well together”.

In addition, aircraft makers could find it more complicated to certify new iterations of older aircraft designs.

Both the 737 Max and Airbus’s popular A320neo are based on aircraft originally designed more than 30 years ago.

Mr Ky said the rules that exempted those systems and parts previously certified would have to be changed.

But this would need to be co-ordinated globally, he said. “We cannot do it in isolation. We need to work with our American colleagues to have an agreed way forward to review the changed product rules.”

Meanwhile, European airlines could look forward to taking delivery of the 737 Max in time for the summer season, Mr Ky added.

Boeing had addressed Easa’s concerns over returning the 737 Max to commercial service, including a modification of the flight control system that was deemed a critical factor in the two accidents.

The next iteration of the 737 Max would include an enhancement to detect potentially faulty sensor readings, he said.

Easa’s recertification follows approval from the FAA last year and more recently from safety regulators in Brazil and Canada.

While deliveries can begin when the green light was given, it could still take time for airlines to put the 737 Max in service as pilots have to be trained in the new systems.