Posted on Feb 24, 2021
CPT Gurinder (Gene) Rana
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What exactly is metal fatigue in the engine of a Boeing 777, especially post takeoff; doesn't engineering endure air worthiness of the plane before it is placed into service and; who is to blame?
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SSG Bill McCoy
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Edited 1 mo ago
I am NOT an expert, nor am I a metallurgist. After the Army, I was the head of security for the largest Specialty Steel producer of stainless, titanium and other alloys used in aerospace, military and automotive applications. I do know that when those metals were produced, stringent testing was done prior to whatever metals were delivered to our customers. Just from our product brochures, it was also obvious that, in addition to testing, our end products sold were with information about expected lifespan as related to "metal fatigue."

That said, the fatigue can be a product manufacturing issue, or an issue with using the final product beyond it's intended lifespan. While there is always a area of "between" point A and point B, the recommended parameters in aerospace are pretty stringent. When components go beyond their maximum (point B) lifespan, "fatigue" becomes a major issue.
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CPT Gurinder (Gene) Rana - Not neccesarily a metals fatigue. Forensic metals analysis will say, and that can take months, until then its speculation. It could just as easily have been FOD-Foreign Object Damage, that could be ingested metal parts from taxi or takeoff such as screws, parts from a tug or line tractor or the street sweeper typical on airport taxi areas. Bits of luggage or service vehicles, rocks strewn from careless operators or off their tires of a line truck,, But each of these incidents were on take off climbs. What else is around airports? BIRDS! Bird Strikes have taken down a LOT of airplanes and engines do get damaged from them. I have seen jet engines you can toss a handful of rocks into and all it does is make pretty red rings and shoot sparks out the back, others would be destroyed. Some engines are more prone to damage than others

Worse,, A engine can be damaged and go extended periods before its caught or discovered. This might all be from Bob leaving his flashlight in a intake a year ago.
As to who is responsible? maybe me! Look, once you sign your name or bugg off a part in inspection you OWN it. I worked for years and inspected and worked on thousands of parts for PW alone, then factor in GE, RR, FIAT and a host of other companies. Along with me were many other people from those who did the wax parts for dipping, to the guy running cut off for gates & risers to the guy who did final CMM and Vis-Dim, to the lady who ran the milling machine who machined the mating grooves on the fan frames.

Legal liability can vary. Is the maint, a contract crew? If so, last inspection will be looked at carefully. Was it done by PW maint team at last inspection? If its FOD maybe its Bob back at the service center, or Steve the baggage handler who spilled a bunch of coins out of his pocket when he brought Laverne her Double Iced Mocha macchioto.
Maybe I missed it working overtime and being tired on final Zyglo inspection back in the mid 1990s but unlikely as that was so long ago. (I made time and half over 40 hrs, Double time on Sundays, and Triple time on holidays, So 2 weeks on, I worked max over time, took it easy then did it again so half of each month i was fatigued.)
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CPT Jerry Lucas
CPT Jerry Lucas
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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.
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CPT Jerry Lucas - I would be curious actually WHAT checklists are being run between flights these days on major heavies. The reason I dont work for an airline as a A&P Is its not like the 1970s, where everyone was well paid, typically union and techs were hired to inspect everything. After de-regulation, if the general public KNEW the facts about day to day airline ops, most people wouldnt fly. I am not saying its not safe, but I tried to work for United, Alaska and Southwest, and I can go flip burgers for better money.
Most air terminals very little is done between each flight from what I know. Today might be different and a real A&P might do a visual,, might even do a detailed checklist and do systems checks. But It would be interesting to know.
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SSG Bill McCoy
SSG Bill McCoy
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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.
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SFC Patient Service Tech
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Everything has a breaking point, whether it be people or objects. Perhaps no one is to blame.
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CPT Gurinder (Gene) Rana
CPT Gurinder (Gene) Rana
1 mo
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?
SFC (Join to see),LtCol Charlie Brown,Maj Marty Hogan,Col (Join to see)
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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.
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LTC Jason Mackay
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Could be a flaw in the titanium structure. Something mundane as a few degree temperature shift during the forging process (like a cold draft be opening a door). Could be a few thousands or tenths of an inch off tolerance during a very complicated 5 axis mill process (blades are curved in three dimensions and hollow. Titanium is challenging to machine and weld.)

Everything has a statistical mean time to failure, but statistically there are outliers. Always are
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CPT Gurinder (Gene) Rana
CPT Gurinder (Gene) Rana
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A1C (Join to see), 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.
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SSG Bill McCoy
SSG Bill McCoy
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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. :)
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CPT Gurinder (Gene) Rana - Id be happy to discuss, But I am not a purchasing agent, But I can point you to my wifes company, and others locally, Materials are a huge deal right now. Having worked with companies that outsourced, thats a complicated topic, However I believe there is a middle ground where everyone can come out ahead. But here in the US, in manufacturing its always the new brilliant idea, usually have some merit, but like fad diets, they have downsides.
5S and JIT for example, Im big on stockpiling stuff I KNOW will be useful. Lets say sales projections are that you KNOW you will use X amount of T6 aluminum (Billet, bar, tube or sheet) and, A whole saler has a good price, Speculating you KNOW the demand over the next year is going to drive up prices, So it makes sense to stock up, even if you cant use it all, you know you can resell it, likely at a large profit margin to others. Now under 5S and JIT, you ONLY order what you need WHEN you need it.
Well, in my opinion thats idiotic. Whats happened in the last few years, is many people found that without on site QA/QC, the quality slipped, and were too short sighted to ensure quality so, started bringing back those jobs to the US. THEN Covid hit, and that has impacted the mills, suppliers, shipping and the entire chain.
So, many companies that were outsourcing are now trying to stuff a square peg into a round hole and asking shops that downsized to step up production and materials and its creating a huge bottle neck.
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LTC Jason Mackay
LTC Jason Mackay
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A1C (Join to see) happened to see this on Titans of CNC: https://youtu.be/_26tu4c7V88
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