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...

https://cimg6.ibsrv.net/gimg/pprune....1bbed57fd.jpeg
UAL 777
https://cimg0.ibsrv.net/gimg/pprune....8e31d1b385.jpg
Ground debris

Whoops fairly dramatic, both the footage and the debris.
Pretty lucky that no-one was hurt.

Looks mostly contained, but perhaps a couple of compressor blades seem missing. There is a gap there when you slow down the video.

The high vibration would support a fan blade issue. See the recent JAL event.

Busy days at PW flight safety department.

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 :uhoh:

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/

Underestimation of the fan blade out loads has been a general trend, apparently. See the 737NG and the Southwest event. Perhaps nobody really wants to carry around that heavy structure to cover a rare event.

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?

There is also the engine oil, and some hydraulic fluid, out there.

Who was the engine manufacturer ?

It might just be some of the epoxy composite containment got hot enough to burn. Plenty air to feed the combustion.

ETOPS
 

Would of been interesting midway between the west coast and the destination Hawaii.

Pratt & Whitney

Engine oil or maybe hydraulic fluid.

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

VAS summary video of incident
 

VAS aviation video

I don’t see any hole in the casing. Don’t see any report of debris hitting the fuselage. Is it really an uncontained failure?

if bits fall off its uncontained!

TD,

Was the vibration levels the same on all engine types?
Thanks.

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.