Washington:  Damage to a fan blade on an engine that failed on a United Airlines Boeing 777 flight is consistent with metal fatigue?

So; the stress of age on the metal used in manufacturing the Pratt and Whitney engines on the Boeing 777 caused fatigue that ultimately failed the engine, in flight, causing public safety and security concerns at United Airlines. Who is to blame for stressing that metal into fatigue beyond its recommended age; Airline management, engineers or the flight crew, or all the above? It is sweeping dirt under the rug to conclude engine failure in flight as a natural disaster of air transportation.

CPT Gurinder (Gene) Rana - I recently retired from the company that makes the pylons and nacelles for most Boeing aircraft (Spirit Aerosystems, a former Boeing facility that was sold off in 2005) , including the 777. That aircraft is 26 years old. I'm not sure if the engine (PW4000) is the original engine or not. More than likely, it is not the original engine. At regular intervals, the engines are disassembled and inspected (including non-destructive inspection) for cracks and other wear and tear, with components replaced as needed. While the aircraft is inspected before each flight, internal cracks would not be seen during a visual inspection. When the engine fans are turning, stress is placed on the fan blades, similar to children on a school playground merry-go-round, as it continues to spin, some children cannot hold on to the bars and fall off. The stress of the high speed spinning eventually takes a toll. It doesn't happen very often, I can think of about four times in the past 10 years or so. I had the good fortune of having dinner with a Boeing representative the Monday after the accident, the company is pouring over all the build records and maintenance records, making sure everything was done properly and Spirit Aerosystems is doing the same, making sure every fastener was torqued properly, etc.

CPT Gurinder (Gene) Rana - Sir, I am not saying at all that fatigue caused any accident. I'm only saying that any metal can fail due to fatigue - but also metal can fail due to abuse. I worked an insurance case once where a front fire came off of a car because the spindle broke. In that case, as any suspect metal fatigue case, a forensic engineering business determined it was not fatigue; but an impact.
I don't know enough about the P&W engine/airline event to comment, NOR am I an expert in any sense. As for "who is to blame," it could be any of the variables you mentioned, as well as a maintenance person(s). Whichever it is/was I have no concrete idea.

SSG Bill McCoy - Commercially pure (99.2% pure) grades of titanium have ultimate tensile strength of about 434 MPa (63,000 psi), equal to that of common, low-grade steel alloys, but are less dense. Titanium is 60% denser than aluminum, but more than twice as strong as the most commonly used 6061-T6 aluminum alloy.

A1C Doug Towsley, getting sourced with premium raw materials is elementary in any manufacturing business. All want the best for the least and suppliers capitalize by selling their lower quality yield at a higher price, especially in foreign sales. I comprehend the mechanics and this is why QC/QA is paramount for the manufacturer at source. Ti is produced in the U.S., Australia, India and a few European countries. Cost is high in U.S. and Australia and perhaps slightly lower in Europe. India is cheaper than the rest and Quality products can be sourced from here. Let's discuss, if it is feasible.

CPT Jerry Lucas - Now you're getting into the "Greek" language for me. As I've said, I have only a cursory knowledge or metals, and that's from a security perspective related to pilferage/theft potential. :)

A1C Doug Towsley happened to see this on Titans of CNC: https://youtu.be/_26tu4c7V88

Aircraft is expected to be inspected prior to flight to ensure air worthiness of the aircraft, so the safety and security of customers is assured. Metal fatigue can be realized, correct?
MSG (Join to see),LtCol Charlie Brown,Maj Marty Hogan,Col (Join to see)

CPT Gurinder (Gene) Rana - Yes. But not always. I did PMCS on my vehicle (M113A2) with mechanics all the time. Every now and then, something would break. No rhyme or reason. It just happens.