Excellent Overview- especially the blocker doors! Thanks! Juan. (I posted your link to this video)

At Pratt we call it a liberation whenever a blade comes free. I think you are spot on with this one! Great analysis from the clips we have available. It’s amazing how a small imbalance in the system can create massive vibration. All of those blades are measured and balanced in the stages to maintain equilibrium during rotation. Any sort of mass reduction in a stage gets exaggerated during rotation, which is what we are seeing. I’m a mechanical engineer but work as a quality engineer for Pratt engines. The work engineering puts into these engines is amazing! I’m thinking a fan blade failed due to fatigue or improper inspection testing. I bet a micro crack developed and propagated in one of the blades. More and more we are seeing bad or improper NDT inspection being carried out. The news is blowing this up to get ratings and has very little knowledge on these systems. It’s almost as bad as the B-17 crash where reporters were asking if they recovered the black box lol

Agent JayZ, as far as I'm concerned, you are the Blancolirio of engine experts!

Sounds like an uncontained reporter failure.

AP mechanic here. Excellent video! You and Juan are my 2 favorite aviation channels on KZfaq, great break down of the event from what we know thus far.

Thanks for this video. I enjoy listening to someone who actually knows what they are talking about, and not just some news person.

I believe "Pan-Pan" is from the French word "panne" which would refer to equipment failure. "Mayday" is from "m'aider" which means "help me".

Someone somewhere is thinking "I serviced that engine".

Former GE engineer here - you got everything right. At least, that's what I've been saying. No evidence of anything that spins busting through cases. Watch any blade-out certification test, and it's not hard to imagine the nacelle getting thrown off, but that doesn't count. By the way, for the GE90 on the B777, GE supplied the nacelle - something new. Not sure if that was true for PWA or RR - probably.

the media generally prefers hype and horseshit over sound reasoning

Your definition of a PAN-PAN call is not entirely correct - a PAN-PAN call is an urgent situation but with no immediate danger to people or ship/aircraft

I witnessed the plane shortly after it initiated the left turn. It was coming towards me from the north in a gentle bank and descending through a cloud layer. The plane was much lower than would be normal in that location. At first I thought I was just seeing a condensation trail but quickly realized it was smoke. As it passed overhead I could see a bright orange flame coming from what appeared to be the lower right side of the cowling approximately 5 to 10 feet from the rear of the engine. The cowling was still intact as far as I could see at that point. The plane continued its turn until it was heading back east toward the airport. I continued to visually follow it and approximately 30 to 60 seconds later there was a large puff of smoke at which point it appeared the engine had exploded. I continued to visually follow it until I could no longer see it.

6 months ago and having absolutely no knowledge of jet engines I would have believed most of what the news media is reporting. But, thanks to your great videos that I've been watching I was able to figure out most of the major points you made in this video for myself. Thanks for the education!

Sounds like it was an uncontained engine failure in the sense that the engine failed, and the media was unable to contain their urges to sensationalize it. ;^)

Great analysis JayZ. Good Job. I agree with everything you said. Retired airline pilot here. This was a textbook simulator event. We would train for this type of event every year. The weather was good. It was daylight. Great airport, Aircraft, ATC and well trained pilots.

Good point Jay. Yes. The engine is all still on the wing. What fell to the ground were Aircraft parts. Not Engine parts. Sounds like we had an uncontained media failure.

Being an engineer, I love your explanations, I also love Juan Browne for his pilot perspective. Media - can cut them some slack because 99% of the people couldn't understand contained vs uncontained. In AvHerald's comment sections even the pilots are fighting over it. Engine blew up on some news - sensationalism. My local news "airplane shed parts over Denver" - probably as accurate as any. Me, that's interesting seeing the engine with all the covering removed. Why doesn't that happen when I have a window seat and am shooting video?

I'm an aerospace technician with approximately 7 hours of experience watching turbine engine videos and I have conducted my own investigation of the incident and I have concluded that the engine went "kaboom", not the "Big Badda Boom" as reported in the media as there were no burn marks on the wing and apparently no holes in the fuselage as the passengers were able to video the wobbly smoldering engine. I also believe the engine is not shaking due to imbalance but it is in fact shivering due to it's clothes being ripped off in midair in subzero temperatures.

Excellent video, keep up the good work. So nice to hear cool calm engineering facts. Ive been an engineer working on PT6 TPE-331 and CFM56 for the last 33 years. This is a bit similar to the Southwest Airlines 737 incident in which the tremendous energy from the contained engine failure caused the cowl hinges or cowl latches to fail, thus causing the cowl to break up and separate from the airplane. Most people don't appreciate the amount of energy involved in a broken fan blade. In both the Southwest incident and United 328 incident the engine failures were contained. Well done to the boys who designed the debris containment shield-it worked as advertised.

Jay. It’s great to watch someone explaining the facts about this incident, especially from someone who’s got the credentials to state the facts rather than the media hype. I’ve been following you for years now and it’s great to see you giving some input into the aero side of these turbine miracles you devote your life to. Would be great to hear your opinions in the future about similar occurrences on aircraft incidents and explaining the probable causes. Thanks. Gerry. A humble U.K. based diesel mechanic.

I worked at Rolls-Royce Canada and I knew right away it was missing fan blades from that wobble. Engine design did its job of Containing the failure. Kevlar ring did its job. Worse case engine mounting bolts would have sheared and engine would have detached.

The strange thing is - almost two years ago that same thing happened to an United B777 flight from San Francisco to Honolulu. The damage to the engine and nacelle looks almost identically (one fan blade missing, adjacent one snapped in half, front part of the engine cowling gone), but as this incident happened over the Pacific Ocean, no debris felt onto someone's backyard. I smell a replacement program coming for all those PW4000 fan blades on B777s.

Well done! Blancolerio's report on the plane and your report of the engine were excellent together!

It's pretty clear that mainstream media is less and less about facts but emotions instead and usually the bad ones like fear. I'm really glad that we are in an era where we can easily find correct informations from people that know their stuff like you or Blancolirio but I also would like to mention Mentour Pilot which also covers news in the aviation world and is great at explaining stuff and providing his perspective. Now I hope no one pocketed pieces of the aircraft but left them where they fell for the investigator to examine. BTW I think it wasn't called an emergency landing because the landing was normal and the passengers disembarked normally instead of evacuating with the slides, I guess is a matter of what's perceived as an emergency landing from the outside and what technically is one like in this case it certainly was

Interesting! We agree. My first thoughts after seeing the passengers video was "That doesnt appear to be an uncontained failure." As you said, we cant see the other side of the engine from that video though. I was an engine guy too, now retired. My engines were T.I.N.Y. in comparison, biz-jet apu's and some tiny turbojet noisemakers (BD5J/AD1 Oblique wing POC/NGT 62% flight demonstrator) but the physics and requirements are IDENTICAL from a certification point of view. I want to see some pix of the outboard side of the engine!

This is a great analysis. Journalists don’t write or share the facts anymore. I am glad there are channels like this. I’ve subscribed!

Your recognition of the specialized knowledge that engineers possess is refreshing and appreciated. Good engineers recognize that the mechanics and maintenance personnel also possess the unique mix of knowledge and skills needed to make the whole big thing work. Great video!!

Please don't stop your rantings you, Juan Browne and Victor at Vass Avaition are the no nonsense professionals. You have every right, you all tell it straight! Keep up the great work! Love to learn the incredible design and engineering that make these machines power our world. Bet we all would be lost if there were no turbine engines or those that keep them flying, etc.

New pictures of the engine in the hanger. Looks like it lost containment around the high-pressure compressor. Damage to fuselage and wing.

Thank you for your analysis, and theory about the flames after the fuel had been shut off. This is the first time I have watched your channel, and it's because blancolirio recommended it. I imagine that Juan will incorporate your insights into his follow-up reports on this incident. Keep up the great work!

Absolutely agree with your analysis of the media, funny they haven't grabbed a drone link to the accident. Utter disgusting YT demonetizes Juan's channel for being so informative as a working Pilot's view of incidents like this. Rants are good!!!!

You are the guy who exactly knows what you are talking about. The total control over the subject. Love it.

So you could say that including the nacelle when referring to "the engine" is a lot like including the hood of your car when referring to its engine.

Thanks for sharing. You and Juan Browne bring useful information to this incident.

You and Jaun are just about the only "media" sources I'd trust when it comes to aviation analysis. VAS Aviation does a great job of assembling all the data as well. I don't mean to offend by calling you "media", that term has too many negative connotations lately. We need to coin a new term for experts who actually want to present the "news" with actual facts and data.

I think after seeing some cowling debris I believe that the fifth stage air duct either became disconnected between the engine case and the air to air heat exchanger this would do two things, one set off the fire warning, which it did and inflate the cowling with 600 + degree high pressure air which blew the cowling apart. the evidence is the leading edge of the nose cowl which houses the nose cowl deicing duct was blown completely off the nose cowl and found intact on the ground.

Fox news mentioned a 747 had an engine incident over Holland less than 24 ours after the 777 incident. Fox made an issue of it being "two Boeing aircraft." Having no idea that Boeing does not make aircraft engines.

Thank you for posting this. Both you and Juan (Blancolirio) have a proven record of being tremendously informative, unlike our media. “...the media hit the fan...” 😆

The "news" media is all about ratings. More drama equals more viewership, which means higher rates for their advertising. Doesn't have anything to do with facts or realities. I always visit your channel, Blancolirio's, Day Gryder's and Scott Perdue's to get the straight scoop with no drama or BS. Thanks again for great video.

Blade failed took out another they got kicked out forward damaging the front cowling and causing heavy vibrations which then caused the nacelle to fail and break apart.

I started working on turbine engines in 1968 (you can guess where). I was walking past one of my unit's Hueys once and for some reason, I climbed up to look in the exhaust. There were pieces of turbine blades laying there, from the last hot stage. May have taken a round in the butt. I commented earlier today about the missing blade and adjacent shorter one on Blancolirio's channel. You're right, Juan is the best.

After reading many of the comments I was impressed by the number of professional jet engine technicians on here. If it was uncontained the fuselage would have looked like a strainer.

The TR system on PW engines if I recall correctly is hydraulically operated and given the amount of damage it's a safe assumption to make the fire that we see is from leaking hydraulic fluid (IE oil like you said).

"pan-pan means the vessel's in danger, the passengers should be okay". It lets ATC know there's a problem on board that isn't likely about to turn into disaster. Minor technical issues that are unlikely to take the plane down, or a medical problem. "don't know why you would ever call that".....you would probably call it in the vast majority of all cases, because mayday takes top priority and begins preparations for an incoming possible accident, you can't call it lightly.

Really awesome! Thanks for the coverage of the incident!

It is a tribute to well designed engines, aircraft, and well trained pilots. Probably should not have happened, but given that it did, nice outcome. Nice video.

Thanks Jay, This is why I rely on people like you and Juan Brown, not the fake media for actual facts. Captain Joe, who is a 747 Captain, also has a good review on how the crew handled the 'mayday call'. Spring is not far off, hang in there... 8) --gary

Thx AgentZ for the sharing of your knowledge with excellent diagrams for a clarity on this aviation issue. FWIW in the US Navy along time ago I worked on LM1500s We were given an interesting movie to witness of the intentional ingestion of Fod (an AN 1/4"×1/2" bolt) to a J79 at full power to demonstrate the catastrophic uncontained departure of compressor and turbine blades which resulted in a withering mass of burning debris on the floor of the jet cell and turbine blades inbeded deeper than a 6"scale inserted in the hole. This video left lasting impressions on myself and others who witnessed it how much rotating energy is present in a jet engine and the need to keep all those parts contained in it by ensuring FOD was not encountered. Thank God modern aircraft engines are engineered and constructed of materials as you described that can withstand these tremendous forces to contain in most cases a catastrophic failure like the one on UA flight out of Denver yesterday. Stay Healthy.

Okay, now I have to speak up. Seen too many replies to this man's video from people who don't know what their talking about. First off this man's video is 100% correct. Engine pieces were completely kept internal as they are designed to do. Now from a professional standpoint, I am an x-Airforce Airframe repair specialist. All this "damage" to the main body of the aircraft from all the same photos you all saw were NOT from the internal engine parts. All this other damage was done by the cowling that shredded and came off. When you have all those exterior pieces flying around they will do strange things and they will move aft of the engine. A high speed blade would have gone nearly straight into the fuselage of the plane (some variance for speed of course) but my point is clear. If you do not know what your talking about from a professional stance then please stop posing as someone who knows it all.

Thank you for saying what I thought every time I saw someone say “uncontained”. This was very contained otherwise there’d be a ton of more engine parts strewn around the countryside and more holes in the fuselage and wings.

"The cowling? Well, the cowling is gone." XD I'm impressed that the pylon survived that thrashing. A+ for that engineer.

Thanks so much for the accurate info. It is so nice to have facts and not speculation. having your prospective is awesome!!

Pan-Pan is the Urgency signal, it means I am in trouble and may need urgent assistance shortly. Mayday signals immediate imminent threat of loss of life/craft and assistance is needed immediately by all concerned.

The plane must have been in orbit. I just heard a reporter say that debris landed "thousands of miles below them". To be honest, it did lose a fan blade and it wasn't contained by the cowling as it's supposed to be, so one could call it "uncontained". Unless it's still stuck somewhere in the vicinity of the engine, but it appears to have left the scene.

Realistic analysis. You are not an engineer but you are a great jet engines mechanic. You are humble and this makes you trustworthy.

Great video AJZ. Details without unknowing speculation. Juan Brown really does exceptional work. Be well Sir.

For the media, this is an entertainment event. The more drama the higher the ratings. Facts are not relevant.

Most accurate armchair expert I’ve seen yet. Yes, the nose cowl was blown off, as were the fan and thrust reverser cowlings. The engine is intact. Until the FAA determines what caused the engine failure, United has grounded all of it’s 777 fleet that have the Pratt & Whitney engines, which are the sub-United ones. Our sub-Continental 777’s are still flying.

Thanks I was waiting for your take on it. The video one of the passengers made of the engine was great, it showed the vibration and the spiral turning like you mentioned. It's interesting how the Kevlar band is supposed to stop the blades, certainly a clear picture of it.

Great video - Don't think the shaft would bend as the fan is forward of the #1 bearing slightly so all if the imbalances would be absorbed and transmitted through the bearing housing.

Pure speculation, but perhaps there are some similarities between this incident and the SWA 737 incident where the fan blade failed and was contained, but the engine cowling didn't stay together due to the shock of the impact.

Way back when I was still flying for a living with the military, a PAN-PAN call was used when there was a problem that needed to be addressed right away but there was no (further) immediate risk to the aircraft or crew... the situation was stable and under control. MAYDAY is reserved for when there is an immediate threat to aircraft and crew. So... PAN-PAN... an aircraft on the taxiway spots another aircraft rolling onto the active runway with a “remove before flight” ribbon still attached... or a four-engine aircraft has had to do a precautionary shut down of one engine and needs to head back. MAYDAY... engine fire or big problem and I need to get on the ground as quickly as I can

One of the blade fragments was found in the underwing attachment fairing where the wing attaches to the body but that wasn't a structural part. Just a fiberglass cover.

The good old media - one reporter excitedly stated that the plane was thousands of MILES in the air! Duh...where do they find them?

If I were in the left seat I wouldn't distinguish between Pan Pan Pan and Mayday Mayday Mayday. I;d go with Mayday and worry about which was the correct one to use next week

Thank you. Amen on Juan! Kudos to you BOTH.

Good analysis. Very large puff of black smoke in the dashcam video at the time of failure. Also, Juan noted that there was an engine fire alarm going off in the background during ATC comms.

Thanks for the explanation, when I saw the flames I thought I was looking at the exposed insides of the combustors.

Journalism is on life support these days. Most newspapers will just google "jet expert" and call the first number they find without checking if the person knows what they're talking about. That's assuming they even call somebody and don't just guess on their own.

Very professional of you giving props (no pun intended) to Blancolerio. Yes, he does have quite an informative and entertaining Chanel. I do have one question, while the shaft is robust in and of itself, could the vibration that did exist propagate bearing failures which would compound vibration and increased damage? I’m guessing once fuel was cut, the risk of shrapnel reduces immensely (if there even was any risk initially).

It’s a good example of a contained engine failure. The fan case did its job.

Totally agree on the know-nothing media!! When I have personally witnessed an event and then later saw, heard, or read about it in the media, there were no similarities whatsoever.

Well done. I really like your “let’s be real and cut out the B.S.” style. Not enough of that these days.

I would NOT like to be the guy who signed off on the last fan inspection when the FAA comes knocking.

I was immediately impressed how intact that engine looks to be, and still even spinning!!! That fire looked small and I was phondering oil fire too, fuel fire would have been way stronger. Excellent explanation AgentJayZ!

It is amazing to me that engine pylon DID NOT fail. And, it was able to withstand the immense torque generated by the inbalance.

Nice to hear two great voices of reason (you and Juan). What's a coincidence is that there was what looks a lot more like an uncontained engine failure at the same day in the Netherlands. But since that was not in America and it was a cargo aircraft, it hasn't received as much attention, although people got hurt by engine pieces falling on a village: avherald.com/h?article=4e35302b . Turbine blades as far as I can tell, some apparently still hot when they hit the ground, and one got stuck in a car roof, and another piece hit a woman. No fun at all, but no passenger videos of burning engines, so no big media drama. I haven't even seen pictures of the engine, which is weird.

After I watched Blancolirio YT suggested CapitanJoe. Both did a great job explaining the preliminaries. Looking forward to see more videos of yours also. Thanks.

AgentJayZ, Thank you for your professional analysis and opinion. There are some close up pictures of the right side of that engine on Simon Hradecky's Aviation Herald which shows more damage. In one of them it even looks like you can see a piece of a fan (?) blade hanging down from the front bottom of the engine. Thank you Paul

I wonder if this plane was mothballed at any point during Covid. I'm betting we'll see increased maintenance problems and failures due to planes sitting more than they are used to.

An example of using "Pan Pan Pan" would be crossing the Atlantic on the North Atlantic on the Organized Track System (OTS) and you encounter a navigation failure such that your position is doubtful and you have a Gross Navigation Error. I have heard flights on the OTS declare "PAN PAN PAN" to the leave their assigned track and divert to their alternate for that purpose.

Thanks for spreading the truth!

22 years as a railroad freight car inspector and repairman, i feel the same way you do when it comes to train derailments. So much BS is put out from people who have no idea.

Juan Browne and you are a good source for expert opinion, factual analysis and technical reporting. Thanks.

News media to day is not about telling the truth it’s about to get the most people to watch it☹️ Thank you for giving a professional assessment of this 👍

Finally, someone who is making sense.

Thanks, Jay! I'm 4 days behind on this. Glad there's no injuries. Passengers will need laundry services;)

Thanks for the break-down and info. Good stuff, well presented!

Engine is not scrap ? I guess they will do an extremely detailed inspection to figure that out !

A cars hood wouldn't be called an "engine part"...

Excellent video! What you are touching on is the difference between standard English and technical jargon. Both are equally valid in their own contexts. The job of the tech journalist is to bridge that gap. In particular where a seemingly innocuous phrase like uncontained engine failure is concerned. Spot on, J!

I think this would be a helpful analogy regarding engine parts vs aircraft parts: A car is on an over pass when the hood pops up and detaches from its hinges. It sails down and lands in someone’s front yard. No one would say that it was a part of the engine raining down. It’s a part of the car. Lay people (journalists included) don’t really understand what they are looking at when they see an engine hanging from a wing. They don’t understand that it’s an engine wrapped in a nacelle. I bet most aviators, mechanics, etc would point to it and say, “that’s the engine” and not, “that’s the engine wrapped in a nacelle, plumbing, wiring, and all kinds of other stuff.” Calling the whole assembly an “engine” is a helpful shorthand, but it can turn toward misinformation when one or more components of the “engine” become news without actually being a part of the engine.

I’m not sure about this early 777, but most cascades being installed on current airliners are graphite epoxy.

What you are describing coming from the news media is damn near everything they have ever reported on I would say since 2007. They know nothing about the subject they are reporting on and present what they have reported on as the gospel facts from the very first person that will take the time to talk to them hat is if they think they can pass that person for an expert. Every media event report I have ever been directly involved in when reported has had so much erroneous and downright false information in the report it's hilarious. Also enjoyed your rant!

Thanks for your comments. I noticed the same thing and wondered why they said it was uncontained.

The vibration is almost certainly from the unbalanced fan, not from any other swung component.. My question is how the intake cowling was dislodged without the fan containment wrap being perforated. Perhaps the cowling disintegrated first, with FOD for that being ingested and causing the fan blade to fail, rather than the other way around.

Calm , lucid , sensible facts .. thanks :)

If it is a hydraulically actuated thrust reverser the fire might of come from a broken thrust reverser actuator line. The fan cowl that departed probably has a hydraulically actuated power door opening system (PDOS). The hydraulic pump for the fan cowl PDOS and the reservoir probably sits at the 12 o'clock position just inside the pylon. The PDOS system would definitely be leaking dripping skydrol on everything below it. In the video of the plane in the air you can also see the engine oil tank and oil tank filler cap on the left hand side of the fan case.

Awesome stuff AgentJayz!

I really do enjoy, and learn much from your videos. TV news has maybe 60 seconds to convey the essence of what happened to the general public. Contained vs. uncontained definitions is of interest to this audience, but is splitting hairs to non-technical people. Substantial parts departed the AC & landed in a populated area. Lucky no one on the ground was injured.