The US aviation regulator on Wednesday proposed modifications and safety inspections on some models of the Boeing 777 jet, following a number of engine incidents.

The most recent and dramatic one involved an engine on a United Airlines 777 bursting into flames shortly after takeoff in February, scattering debris over a Denver suburb.

No one was injured, but it led to scores of 777s equipped with Pratt & Whitney engines being removed from service worldwide. The US Federal Aviation Administration had ordered checks on all similar engines before any of those models returned to the skies.

On Wednesday, it said these 777 models needed modifications for safety.

"The FAA has determined that further action is necessary to address the airplane-level implications and unsafe condition resulting from in-flight engine fan blade failures," the regulator said in a statement Wednesday, citing three incidents including the one over Denver.

The problem was "likely to exist or develop on other products of the same type design," it added, of which it said there were 54 in the United States and 128 worldwide.

It has proposed installing debris shields on part of the engine casing, new checks on a fan part, and repeated tests on a mechanism supposed to be triggered in the event of a fire.

The US FAA has proposed fixes and inspections on some Boeing 777 models after a number of incidents involving engine disintegration during flight
The US FAA has proposed fixes and inspections on some Boeing 777 models after a number of incidents involving engine disintegration during flight GETTY IMAGES NORTH AMERICA via AFP / Michael Ciaglo

The proposals, which will not be published officially until December 28, are open for commentary until the end of January.

"We support these guidelines, which reflect our work with the FAA to improve the design" of the engines in question, a Boeing spokesperson told AFP.

Contacted by AFP, United Airlines, the only American carrier operating these 777 models, described the proposals as "a good solution".

The company said many of the affected aircraft were already subject to the proposed inspections.

"We expect these planes to join our (operational) fleet early next year," United said.

Even before the Denver incident, air safety regulators had been weighing stricter inspections on the jets and their Pratt & Whitney engines, US officials had said previously.

The FAA reviewed inspection records and maintenance history after an engine fan blade on a Japan Airlines jet fractured in December 2020. The flight landed without injuries.

The 777 is one of Boeing's most successful commercial jets, in service with more than 60 airlines around the world.