United B777 engine failure
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United B777 engine failure
Reports on Twitter that a UAL 777-200 has had an uncontained engine failure on the way from DEN (Denver, Colorado, USA) to HNL (Honolulu, Hawai'i, USA) and returned safely to DEN. Local news report: https://thepostmillennial.com/colora...nited-airlines
There's a twitter post by user @stillgray with video of the failed engine from in the aircraft that pprune doesn't seem to want to include here...
UAL 777
Ground debris
There's a twitter post by user @stillgray with video of the failed engine from in the aircraft that pprune doesn't seem to want to include here...
UAL 777
Ground debris
Yep, fan blade release, extreme vibration fails the inlet attachment and it detaches, resultant aero loads and vibration fail most of the rest of the nacelle.
It was during the 777 program that Boeing discovered that the fan blade out vibration levels where considerably higher than what had been previously assumed (presumably aided by the much higher bypass ratio that the 777 engines had compared to previous big fan engines).
Given this even and the fore mentioned JAL event - it would seem that even the higher loads that were used during the 777 design/cert program were not high enough
It was during the 777 program that Boeing discovered that the fan blade out vibration levels where considerably higher than what had been previously assumed (presumably aided by the much higher bypass ratio that the 777 engines had compared to previous big fan engines).
Given this even and the fore mentioned JAL event - it would seem that even the higher loads that were used during the 777 design/cert program were not high enough
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tower audio
Local radio station KDVR has the tower audio. About what you would expect.
Evidently I'm not allowed to post URLs. Try this instead:
kdvr dot com slash news/local/listen-mayday-call-from-crew-of-united-flight-328/
Evidently I'm not allowed to post URLs. Try this instead:
kdvr dot com slash news/local/listen-mayday-call-from-crew-of-united-flight-328/
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Given this even and the fore mentioned JAL event - it would seem that even the higher loads that were used during the 777 design/cert program were not high enough
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A curious question from an amateur
It looked like the engine was still receiving fuel and burning away happily after the pilot would no doubt have hit the fuel cutoff switch. Why would that be?
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Some similarity with the South West secondary events. The engine itself does a good job of capturing the high energy blade pieces. Unfortunately some of the blade pieces find their way forward of the containment belts and chew into the soft inlet. with a big slashing effect. If the slash gets very long circumferentially then the cowl becomes limited in vibration. looking at the various video feeds on the nws, the shiny front lip of the cowl can be seen after the initial event still attached. Later on in the flight it is now missing.
It is not good that the engine nacelle (reverser) caught fire. The smoke behind the engine does not match a fuel fire and neither does the flame color in the videos. Quite possibly the non-metallic vanes in the reverser are what is burning. The ability to extinguish this in flight is challenging, but at least the slip stream keeps it away from the wing spar. I would be interested to know how the fire fighters addressed this on the ground.
I suspect there will be a few lessons learned here
It is not good that the engine nacelle (reverser) caught fire. The smoke behind the engine does not match a fuel fire and neither does the flame color in the videos. Quite possibly the non-metallic vanes in the reverser are what is burning. The ability to extinguish this in flight is challenging, but at least the slip stream keeps it away from the wing spar. I would be interested to know how the fire fighters addressed this on the ground.
I suspect there will be a few lessons learned here
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Technically contained vs uncontained for certification is only concerned with rotor parts inside the engine. So while the severe vibration causes nacelle parts to fail they are not proof of an uncontained failure.
The fan parts are allowed to impact up to +/- 15 degrees forward / aft radially but must not exit the fan other than out the back after they’ve been stopped so to speak.
The fan parts are allowed to impact up to +/- 15 degrees forward / aft radially but must not exit the fan other than out the back after they’ve been stopped so to speak.
