Some 128 Boeing 777 aircraft using the same Pratt & Whitney engine which failed on a flight out of Denver have now been grounded, a spokeswoman for the giant US planemaker confirmed on Monday. "I have just had confirmation that all the 777s equipped with this engine have been grounded," she said in a text message to AFP. As well as United Airlines, the PW4000 engine type was also used by Japan's ANA and JAL groups, plus South Korea's Asiana Airlines. In a statement Sunday, the company had recommended that all the aircraft concerned should be grounded as US regulators investigated a United Airlines flight which was forced to return to Denver airport after one of its engines caught fire and broke up. A video shot from inside the aircraft -- which had 231 passengers and 10 crew onboard -- showed the right engine ablaze and wobbling on the wing of the Boeing 777-200. Its front cowling -- which landed in the front yard of a house, missing it by inches, was entirely missing as the aircraft returned to Denver airport. There were no injuries on the plane or on the ground, authorities said. mra/pn/bmm/txw