Aerospace giant was said to be working with the FAA to strengthen the covers
Investigators have attributed Saturday's incident in Denver to a fan blade that broke off due to metal fatigue and apparently breached the engine cover
The planemaker and the FAA had been discussing potential fixes for about two years, following an earlier incident in 2018, according to the Wall Street Journal
On Tuesday night, the FAA ordered inspections of all Pratt & Whitney engines
Although immediate attention has focused on the engine's manufacturer, Pratt & Whitney, Reuters has reported that its casing is manufactured by Boeing
Both Boeing and the FAA avoided discussing specifics on the efforts to modify the 777; such changes typically require significant evaluation and testing