New York – The U.S. aviation regulator on Tuesday ordered a deeper inspection of the engines similar to the ones on a Boeing 777 aircraft that suffered a spectacular failure over Denver days earlier. The incident, in which a Pratt & Whitney engine burst into flames and scattered debris over a Denver suburb shortly after takeoff for Honolulu, led to scores of Boeing 777s being grounded worldwide over safety concerns. "U.S. operators of airplanes equipped with certain Pratt & Whitney PW4000 engines (must) inspect these engines before further flight," the Federal Aviation Administration (FAA) said. The regulator said it was issuing the order "as a result of a fan-blade failure that occurred Saturday on a Boeing 777-200 that had just departed from Denver International Airport." Before they can return to the skies, "operators must conduct a thermal acoustic image (TAI) inspection of the large titanium fan blades located at the front of each engine. TAI technology can detect cracks on the interior surfaces of the hollow fan blades, or in areas that cannot be seen during a visual inspection," it said in a statement.