Posted on 03/10/2021 10:47:35 AM PST by CondoleezzaProtege
The United States National Transportation Safety Board (NTSB) released an update on Friday about the United Airlines Boeing 777 engine incident.
In late February, the aircraft was climbing out of Denver International Airport (DEN) when the pilots throttled up the engines in anticipation of turbulence. Shortly after that, a loud bang and fire coming from the engine led the pilots to bring the plane back to Denver.
United Airlines, shortly after, voluntarily removed 24 of its Pratt & Whitney 4000-powered Boeing 777 aircraft from service. The airline is working to fill in the gaps in its schedules as these aircraft remain parked temporarily.
The NTSB almost immediately began looking at the engine itself. That analysis is ongoing. However, the initial damage found fire damage, consistent with the incident, but there were damaged fan blades.
Two blades were fractured when the NTSB looked at it. The evidence with one of the blades was consistent with fatigue. Another blade had “shear lips that were consistent with an overload failure.”
(Excerpt) Read more at simpleflying.com ...
I wonder how many cracked blades will be found when the engines are inspected.
Oh look....cookie
So it was the engine rather than the aircraft. Faulty design? Faulty materials? Faulty assembly? Faulty maintenance? Or was a combination of two or more of these things?
Probably manufactured in China.
Which at that moment was only about 7,500 feet above the dirt below and not enough to clear the mountains in front of him!!!
Inspection intervals are set by known knowns - knowing in advance the failure rates.
Manufacturer has to be relentless in testing and gathering data to seek failure trends before they happen - that can get expensive. Of course, not as expensive as some lawsuits....
(I have had engines fail spectacularly during test - sick sound, sicker feeling).
It will be interesting to see what comes out of this. Is there a design or manufacturing issue and the blades don’t have the expected lifespan? Or did something happen to this particular engine that caused non-obvious and unexpected damage? Something like flying through bad hail or extreme cold or FOD...
That accident started a major movement to stop ‘uncontained’ engine failures, where the blades fly out. That probably saved this one.
Remains to be seen, BUT I have heard that a lot of the airlines are outsourcing the maintenance and overhauls to places like El Salvador and other 3rd world places. They may have just ‘pencil whipped’ it and sent it back to service....................
Very likely a combination. Nobody checked and noticed stress fatigue and NDT probably hadn’t run any scheduled tests as they cost too much.
I recall having seen a documentary on the DC-10 crash in Iowa sometime in the 80s. I recall someone (The NTSB?) having made a public request in the area for the engine parts that fell off during the incident. I think a farmer found the pivotal part in his corn field.
IIRC the final "diagnosis" was that the fan blades had been manufactured from metals (titanium?) that contained some kind of chemical impurity.
Of course you'd surely know more about that incident (and others) than I do.
You’d know about the compressor blades versus the turbine blades then and the turbine blades is usually where we’d find more fault unless there was something ingested. One woman was ingested into a CF-18, but thankfully the chin strap wasn’t on and the helmet went first and destroyed the engine. That was one sweaty guardian angel that day.
I found a lot of guys will pencil whip things too, like the herc that dropped it’s retardant and when it pulled up both wing spars failed and the wings folded up and that was all she wrote.
No, that one was caused by failure of the disk holding the blades.
https://en.wikipedia.org/wiki/United_Airlines_Flight_232#Failed_component
But those were clearly fan blades. I've never seen those break off - usually just compressor blades that snap and create havoc all the way out.
I have cleaned plenty of bird guts off of fan blades, though - it takes a lot of birds to bring one down.
Can anyone shed light on whether the lack of debris entering the cabin or the nearby fuel tank was random luck? It looks like debris blew somewhat down and out the right (outside) area of the nacelle.
Some P&W engine testing is done on software operated by a sketchy sub-contractor in East Hartford who hires illegal aliens with aerospace bachelors degrees would be my educated guess.
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