DENVER – The sound rumbled across the sky above Broomfield on Saturday afternoon. What followed was something equally unnatural and dangerous: small and large pieces of a massive turbine engine began to rain on neighborhoods below the flight path of United Airlines Flight 328.
“We looked up into the sky and saw a lot of dark smoke and things raining down from the sky,” Lisa Hill told Denver7, who was walking in an open space near her home. “We thought maybe birds hit the engine, and it was the little things we saw falling, but it was actually big things, they just looked small from a few miles away.”
The Boeing 777-200, en route to Honolulu, experienced only a right-hand car interruption shortly after takeoff. The plane turned around and returned to Denver International Airport and landed safely. No one on board or on the ground was injured.
But what caused such a spectacular uncontrolled engine failure? Investigators will be looking into the response to such a rare event in the coming months. But Tom Haueter, ABC News consultant and former NTSB director of the Aviation Safety Office, has some insight into what they can look for.
“What will investigators look at, collect all the parts, look at the photos, look at the maintenance records of the engine, the history of the engine, when it was made, how long it is, how many hours it is? “How many cycles, how many flights were on it, are starting to gather all the information,” Haueter told ABC News.
Shortly after the incident, photos and videos began appearing on social media. For aviation experts like Haueter, these posts gave an idea of what might have happened.
‘When I look at the pictures I saw, it appears that a piece of one of the fan blades, these are the large blades that you can see when you look from outside the engine, there is a piece of a fan blade missing , and on another photo I can not see if another fan blade is completely missing, ”said Haueter.
Garbage from the engine fell on a wide area of Broomfield and affected homes and property in the Northmoor and Red Leaf neighborhoods. Parts were seen scattered in parks, lawns and on rooftops. But Haueter said one of the most important pieces the authorities need to find is the missing fan blade.
‘The most important piece to come back to is the fan blade, or pieces of the fan blade. You want two sides to the failure so you can say, ‘OK, that’s what happened.’ Was there a wink in the blade? Was there a fault in the blade? Was there something else going on? There are many pieces, but only a few pieces are very important for the investigation, ‘he said.
In a video captured by a passenger aboard a Flight 328 on Saturday, the flying car could have crashed before pilots made an emergency landing. Passengers probably felt the explosion and vibrations all the way into DIA.
‘Well, basically when something like this happens, the engine is extremely out of balance. Turbine engines are designed with all the massive rotations to be very smooth of course. If you lost a piece of it, you now have a lot of vibration. Parts start rubbing together that do not normally rub. “You start vibrating parts for the fuel system loose, so suddenly you can get a fuel line,” Haueter said. ‘You have friction from this massive engine grinder that is still spinning and destroying different pieces of metal while doing so. It looks pretty dramatic, let’s be honest, but unless the engine is really catching fire and a big fire is going on, it looks worse than it is. ”
Investigators will not know exactly what happened before they tore up the engine. A team from the National Transportation Safety Board has gone to the area to take over the investigation, police said.
Although Haueter said what happened on Saturday is very rare, but some do not take chances. The Japanese Ministry of Transport has instructed Japan Airlines and All Nippon Airways, which operate aircraft with the same range of engines, to land the Boeing 777s in their fleet.
The Department of Transportation also refers to a ‘serious incident’ that took place on a flight of Japan Airlines on December 4 last year, where the same type of engine (Pratt & Whitney PW4000 series) was damaged.