sgbroimp wrote:

So to me the ETOPS question: Would this bird have made it halfway to HNL (or half way back to land) in this condition? If not, was this the one in ______ (fill in the number if you know it) flights that ETOPS theory was based on? Maybe silly me, but over water I like lots of engines.

I could be wrong, but it seems to me that if it didn't make it, more engines most likely wouldn't have helped.

Antarius wrote:

catiii wrote:

sgbroimp wrote:

So to me the ETOPS question: Would this bird have made it halfway to HNL (or half way back to land) in this condition? If not, was this the one in ______ (fill in the number if you know it) flights that ETOPS theory was based on? Maybe silly me, but over water I like lots of engines.

Well unfortunately for you practically every passenger airliner going over the water has two engines.

First, ETOPS isn't a "theory." It's a standard that requires approval. Second, it's not based on making it "halfway to HNL or halfway back to land." It's a 180 minute ETOPS to Hawaii. Third, "making it "halfway to HNL or halfway back to land" still results in the airplane being in the water so...not the outcome you're looking for. All the engines in the world won't help you at that point. You could have 30 engines and if you only make it halfway what's the point?

And to add, how many issues have we had that ended badly due to engine out? I can think of BA 38, although that was a FOHE issue and theoretically could have happened on a quad.There was the Gimli Glider, but that was due to a fueling issue, not the number of engines.

ETOPS isn't a problem.

The only ones I can think of all involve the crew shutting down the good engine instead of the bad engine (BMA, TransAsia, the recent Air Force crash).

Revelation wrote:

A tweet I found interesting from @RWMann describes a certain pathology:

A repeating theme is fan blades appearing to migrate forward of containment ring at failure, which takes the lip out, and the rest of the nacelle is blown apart by the air stream, which causes damage to fuselage or flying surfaces. Engine certification test models need revision.

Ref: https://twitter.com/RWMann/status/1363852138682716160

I will be curious to see how that issue is addressed if there is a determination made that doing so is necessary.

Revelation wrote:

Partially fits the description of the AF A380 that landed in Newfoundland, no?

In August 2019, the BEA announced that a part from the fan hub recovered from Greenland had been examined by the manufacturer Engine Alliance under BEA supervision. Metallurgical examination of the recovered titanium fan hub fragment identified a subsurface fatigue crack origin. The fracture was initiated in a microtextured area approximately in the middle of the slot bottom. Examination of the fracture was ongoing.

Ref: https://en.wikipedia.org/wiki/Air_France_Flight_66

* image removed for brevity *

Ref: https://www.dailymail.co.uk/travel/trav ... blast.html

That was not a blade migrating forward, but a fan disc failure which outright destroyed the fan case. Disc failures are never supposed to happen because they can't be realistically contained. Blade failures are not intended to happen, but they can be contained, so there isn't quite as much emphasis on prevention as with disc failures.

There have been other instances of non-trivial secondary damage from blade failures, though, so I'm sure there will be discussion about this.

Revelation wrote:

catiii wrote:

If by "partially fits the description" you mean it was an engine failure, then yes.

The common elements I was thinking of were "fan blades appearing to migrate forward of containment ring at failure, which takes the lip out, and the rest of the nacelle is blown apart by the air stream". As you say it's a different design, and probably a different failure mode (probably not hub failure or all the blades would have departed) but maybe we have blades migrating forward and taking the lip out and in the AF case some but not all of the nacelle ripped apart by the airstream.

I would imagine the intake lip and other parts of the nacelle could easily be dislodged just from the lateral forces of an asymmetrically imbalanced engine when it is missing one or more fan blades. I don't think you necessarily need any part to travel forward for that to happen.

889091 wrote:

CALTECH wrote:

Wing To Body Fairing, it attaches to the wing and fuselage......

Is there an exit point? If not, can we safely assume that whatever punctured the fairing is still somewhere within the fairing? Was the centre fuel tank compromised? Looks like there is a wet patch underneath the hole, but it could just be melting snow.

The AC Pack is in that area behind that fairing...

The wetness on the ground could be water dripping from the packs, or residual fire fighting foam/water the fire department might have used.

The grounding affects both 777-222s with PW4077s and 777-222ERs with PW4090-3.

CALTECH wrote:

The grounding affects both 777-222s with PW4077s and 777-222ERs with PW4090-3.

i.e. all (both) PW4000 engine types with the 112" fan. ( and the same blades ?)

catiii wrote:

Revelation wrote:

Partially fits the description of the AF A380 that landed in Newfoundland, no?

Different engine, different manufacturer (although Pratt is part of the alliance), different airframe and the supposition here thus far is that the blade failed and not the hub although it is entirely too soon to tell.

If by "partially fits the description" you mean it was an engine failure, then yes.

Otherwise, no.

Different engine, same manufacturer (Pratt is the fan disk supplier on the GP7200), but totally different failure mode. On the GP, this was a disk failure, while on the 4094, pictures would tend to indicate a more common fan blade rupture.

The main similarity between both pictures is the disappearance of the nacelle. But it stops there; nobody expects the nacelle to withstand a disk failure, while it should survive a fan blade out event as FBO is a design case for the powerplant system. The Southwest 737NG and that one would tend to indicate Boeing nacelles are weaker as they should be.

Pilots deserve serious praise, especially because the emergency occurred in DEN known for it's turbulence. My old office was in Broomfield when I lived there so these photos look very familiar.

Honest question: Would this event be similar to UA 232 except the fan blade didn't blow out the hydraulics on the plane? I seem to recall that was another faulty fan blade issue.

N649DL wrote:

Honest question: Would this event be similar to UA 232 except the fan blade didn't blow out the hydraulics on the plane? I seem to recall that was another faulty fan blade issue.

Rev summed up pretty well a couple of posts back. UA232 was caused by a fan disc, not blade.

viewtopic.php?f=3&t=1458015&start=300#p22661747

Anyone who has viewed external stores separation videos can attest modeling and predicting of the paths of dropped objects is pretty difficult. I’ve seen ones where the bomb goes OVER the wing or drop tanks folded over the leading edge. These on test, under a flight test card. A C-5 had entry door come lose and went into the #2 engine.

Antarius wrote:

catiii wrote:

sgbroimp wrote:

So to me the ETOPS question: Would this bird have made it halfway to HNL (or half way back to land) in this condition? If not, was this the one in ______ (fill in the number if you know it) flights that ETOPS theory was based on? Maybe silly me, but over water I like lots of engines.

Well unfortunately for you practically every passenger airliner going over the water has two engines.

First, ETOPS isn't a "theory." It's a standard that requires approval. Second, it's not based on making it "halfway to HNL or halfway back to land." It's a 180 minute ETOPS to Hawaii. Third, "making it "halfway to HNL or halfway back to land" still results in the airplane being in the water so...not the outcome you're looking for. All the engines in the world won't help you at that point. You could have 30 engines and if you only make it halfway what's the point?

And to add, how many issues have we had that ended badly due to engine out? I can think of BA 38, although that was a FOHE issue and theoretically could have happened on a quad.There was the Gimli Glider, but that was due to a fueling issue, not the number of engines.

ETOPS isn't a problem.

Gimli Glider (Air Canada Flight 143) was not over water; its flight path was YUL-YOW-YEG.
Air Transat Flight 236 could have ended badly due to a fuel leak.

WayexTDI wrote:

Antarius wrote:

catiii wrote:

Well unfortunately for you practically every passenger airliner going over the water has two engines.

First, ETOPS isn't a "theory." It's a standard that requires approval. Second, it's not based on making it "halfway to HNL or halfway back to land." It's a 180 minute ETOPS to Hawaii. Third, "making it "halfway to HNL or halfway back to land" still results in the airplane being in the water so...not the outcome you're looking for. All the engines in the world won't help you at that point. You could have 30 engines and if you only make it halfway what's the point?

And to add, how many issues have we had that ended badly due to engine out? I can think of BA 38, although that was a FOHE issue and theoretically could have happened on a quad.There was the Gimli Glider, but that was due to a fueling issue, not the number of engines.

ETOPS isn't a problem.

Gimli Glider (Air Canada Flight 143) was not over water; its flight path was YUL-YOW-YEG.
Air Transat Flight 236 could have ended badly due to a fuel leak.

True. my point was that the Gimli Glider incident would have happened on a quad or a twin. Your example (flight 236) is also the same case.

CALTECH wrote:

889091 wrote:

CALTECH wrote:

Wing To Body Fairing, it attaches to the wing and fuselage......

Is there an exit point? If not, can we safely assume that whatever punctured the fairing is still somewhere within the fairing? Was the centre fuel tank compromised? Looks like there is a wet patch underneath the hole, but it could just be melting snow.

The AC Pack is in that area behind that fairing...

The wetness on the ground could be water dripping from the packs, or residual fire fighting foam/water the fire department might have used.

Also it snowed a little bit pretty much right after that flight landed in the evening, but the next day was warm and things melted fast.

Any chance the missing blade might be somewhere in that fairing?

armagnac2010 wrote:

The main similarity between both pictures is the disappearance of the nacelle. But it stops there; nobody expects the nacelle to withstand a disk failure, while it should survive a fan blade out event as FBO is a design case for the powerplant system. The Southwest 737NG and that one would tend to indicate Boeing nacelles are weaker as they should be.

It is worth clarifying - in the UAL 328 incident, the fan and fan casing remained largely intact. The inlet is gone, as are the cowls behind the inlet that cover the fan case.

In the AF 66 incident, the fan disc failure largely destroyed the fan case. What remained of the engine was several feet shorter than what a failure equivalent to UAL 328 would have been.

Because engines are usually shown with the entire inlet and all cowlings attached, or with none of them at all attached, I looked up some comparison photos that may help some readers.:

UAL 328 side view, after landing - the tan section to the right is the intact fan case.

Engine Alliance GP7000 Ground Display - a similar tan fan case section is visible in this image. The engine inlet is attached to the left, but the cowlings have been removed.

Air France 66 Incident Photo - Note that the tan section is mostly gone. The green primer coated section that remains is visible behind the fan case in the above GP7000 photo.

Spacepope wrote:

Any chance the missing blade might be somewhere in that fairing?

Doubtful. There are pics or vids showing the entire diameter of the fan shroud. There is no signs that a fan blade departed laterally. The only way you'd find a fan blade in that fairing is if it exited the back of the engine and made a 90 degree turn towards the fuselage, unlikely. Or if the fan blade exited forward, also unlikely.

Yes, that's exactly the whole point.

On AF66, the GP7200 engine casing is gone, the nacelle is not expected to hold the thing together.

On UAL328, the engine seems largely intact (beyond the fan blades), however the whole propulsion system collapsed, caught fire and so on. This should not be.

dragon6172 wrote:

Spacepope wrote:

Any chance the missing blade might be somewhere in that fairing?

Doubtful. There are pics or vids showing the entire diameter of the fan shroud. There is no signs that a fan blade departed laterally. The only way you'd find a fan blade in that fairing is if it exited the back of the engine and made a 90 degree turn towards the fuselage, unlikely. Or if the fan blade exited forward, also unlikely.

We've had several CFM-56 failures where the detached fan blades exited the nacelle forward, then striking the airframe at or behind their original position, including the one where the passenger was killed. Perhaps the possibility is more likely than it would appear.

sgbroimp wrote:

So to me the ETOPS question: Would this bird have made it halfway to HNL (or half way back to land) in this condition? If not, was this the one in ______ (fill in the number if you know it) flights that ETOPS theory was based on? Maybe silly me, but over water I like lots of engines.

It’s not a number of engines question, it’s a recommended maintenance operations and material reliability question. The PW inspection recommendations or materials themselves may likely require addressing when more is known.

Remember PAA 843? This is why number of engines is irrelevant if just one fails spectacularly.

https://youtu.be/_-fNahas8Ro

Spacepope wrote:

We've had several CFM-56 failures where the detached fan blades exited the nacelle forward, then striking the airframe at or behind their original position, including the one where the passenger was killed. Perhaps the possibility is more likely than it would appear.

Just to make sure we are on the same page, neither of those incidents had fan blades exit forward and impact the fuselage. The fan blades damaged the nacelle structure forward of the containment shroud and then the inlet/nacelle pieces impacted the fuselage.

Seat1D wrote:

gwrudolph wrote:

I think all parties are being conservative as a result of the MAX situation. All had egg on their face big time

you bring up a good point. politics are ALWAYS at play. Makes you wonder if this happened in the middle of the summer with no pandemic, would the grounding have occurred. On top of that, lets say there was never an issue with the MAX, no pandemic and it in the middle of the super busy season, I{m not really sure the 777 PW fleet would have been grounded,.

Literally my thinking. I think not as well, nor do I think the UK has any reason to now other than that's the kind of world we live in now.

Aaron747 wrote:

sgbroimp wrote:

So to me the ETOPS question: Would this bird have made it halfway to HNL (or half way back to land) in this condition? If not, was this the one in ______ (fill in the number if you know it) flights that ETOPS theory was based on? Maybe silly me, but over water I like lots of engines.

It’s not a number of engines question, it’s a recommended maintenance operations and material reliability question. The PW inspection recommendations or materials themselves may likely require addressing when more is known.

Remember PAA 843? This is why number of engines is irrelevant if just one fails spectacularly.

https://youtu.be/_-fNahas8Ro

Isn't ETOPS "Extended-range Twin-engine Operations Performance Standards"?
Its new iteration that includes four-engine aircraft is called EDTO.

I wonder with the grounding of the PW 777s, does this mean UA's 763 and 764 are safe to back fill right now and not be stored? I know there were rumors that the 764s might be going away during COVID.

NTSB Briefing

https://youtu.be/-VfGJsfS13g

D L X wrote:

gwrudolph wrote:

I think all parties are being conservative as a result of the MAX situation. All had egg on their face big time

i think all the parties are responding strongly because with air travel so low right now, this won’t hurt particularly much in comparison to times when fleet utilization is maximal.

Though there will be an impact in the future, Boeing is setting a precedent for future groundings. So the next time a PW GTF powered A220 or A320, or Trent 700 A330 or Trent 1000 787 has an issue, should we ground those planes? The PW GTF and Trent 700 has had uncontained engine failures at much younger age.

And photos on the NTSB Flickr account

https://www.flickr.com/photos/ntsb/

A few things from the NTSB briefing:
There are preliminary indications of metal fatigue...ie fan blade fatigue.
At this point nothing appears to have penetrated the containment ring....they technically do NOT consider this to be an un-contained engine failure.
Sound like the FAA and PW are coming up with a service bulletin....ie increased frequency of inspection.
Fuel to the engine was turned off so they are investigating why there was fire.
Also trying to sort out why the cowling came off.

dragon6172 wrote:

Spacepope wrote:

Any chance the missing blade might be somewhere in that fairing?

Doubtful. There are pics or vids showing the entire diameter of the fan shroud. There is no signs that a fan blade departed laterally. The only way you'd find a fan blade in that fairing is if it exited the back of the engine and made a 90 degree turn towards the fuselage, unlikely. Or if the fan blade exited forward, also unlikely.

Interesting that the fan shroud/ring cowling is intact...except for a diagonal slice through it. I've seen speculation from a UA pilot that this is evidence of a fan blade exiting forward, slicing through the ring, causing it to separate, and then leaving the entire rest of the cowling vulnerable to disintegration just from speed.

https://youtu.be/EwNCCrjMmeg

litz wrote:

And photos on the NTSB Flickr account

https://www.flickr.com/photos/ntsb/

The photo labeled DEN 5 appears to show the object that caused the damage to the wing-body fairing was moving forward at relatively significant speed. It was heavy enough it appears to have creased the lower wing skin, which is fairly thick aluminum, before entering the fairing, which of course is very thin. I could easily see this damage having been caused by one of the blade fragments.

Another photo shows the blades have all been removed from the engine and were at that time in the hangar with the aircraft, along with quite a few pieces of the cowl that I presume were recovered from along the flight path.

The slat section just outboard of the engine looks like it might have some minor deformation. Pieces of the cowl hitting it would make sense.

Haven't read this entire post so sorry if someone beat me to this...but there has been some bad press coverage on this. NY Post has pic of AA 777 and says 777s will be grounded. Noooo, 777s with PW engines, which AA does not have. The Today show talked about another potential black-eye for Boeing. Nooooo, this was a PW issue. I know the press doesn't have the aviation knowledge that we all do here at a.net. But still, it's lazy. IMO, this was another example of the greatness of this industry and its equipment. A massive 777 can return safely with one engine while the other one rocks & rolls and burns. Calm and well trained pilots and ATC personnel. This made me proud of this industry. I didn't look at this as something to shake my head at and say tsk, tsk. By the way, I recommend the five part series "21st Century Jet; the making of the 777" on youtube. Really good.

No, it's a "Boeing engine" according to the NY Daily News: "A Boeing engine also reportedly exploded over the Netherlands Saturday, dropping debris that injured a couple of people on the ground."

https://www.nydailynews.com/news/nation ... story.html

Here we go...

joeblow10 wrote:

acavpics wrote:

Does it look like another Southwest 1380-style accident?
If so, then they are lucky as it could have resulted in injuries and even fatalities

WN1380 was an absolute freak accident - there have been a number of fan blade incidents before and since, and none have ever led to the exact separation needed of parts/debris to take out a single window.

That said - this certainly does appear to be a fan blade failure. And not the first for PW on these engines... me thinks suggested inspections are coming

I do recall a Delta Airlines MD88 or similar having an engine explosion, tearing through the fuselage killing two passengers.

wjcandee wrote:

No, it's a "Boeing engine" according to the NY Daily News: "A Boeing engine also reportedly exploded over the Netherlands Saturday, dropping debris that injured a couple of people on the ground."

https://www.nydailynews.com/news/nation ... story.html

Here we go...

there is another thread about the Longtail

hivue wrote:

Yes, I would assume cowl debris would be blown straight back from the engine under those circumstances. That's why in the case of WN1380 I was very surprised to see that fan cowl debris had impacted the fuselage at the row 14 window. The math involved may be a lot more complex than it at first appears.

After reviewing the initial images of the aircraft overflight, the rear section of the engine (around the hot section) was intact until it was burned away, pretty much eliminating any of the turbine blades causing the wing/body fairing damage.

That leaves the possibility of the fan blade piece or, as you suggested as a possibility, portion(s) of the nacelle and cowling as the cause of the hole in the fairing...

N649DL wrote:

I wonder with the grounding of the PW 777s, does this mean UA's 763 and 764 are safe to back fill right now and not be stored? I know there were rumors that the 764s might be going away during COVID.

It would take months to reactive the B763 and B764s that are in storage, to prep for return to service, and get all maintenance checks up-to-date. It is not a small undertaking to return aircraft from storage in a short timeframe.

Its far easier both in time and cost to complete the emergency inspections over the next few days/weeks than to go down that route.

ABC News is reporting metal fatigue as the culprit, citing the NTSB:

https://abcnews.go.com/US/damaged-fan-b ... d=76055409

2175301 wrote:

ABC News is reporting metal fatigue as the culprit, citing the NTSB:

https://abcnews.go.com/US/damaged-fan-b ... d=76055409

Incorrect - the NTSB said the fan blade showed signs of metal fatigue. They didn't say it's the culprit.

The reason for the grounding isn’t the fan blade failure itself but the performance of the containment system. It does look like a blade has come forward and sliced the intake cowel and then caused that hole in the wing box fairing. The intake has then separated but fortunately not gone over the wing and hit the tail plane.

The aerodynamic forces on a fan blade are forward (forcing air rearwards) so when released they tend to go forward. I’ve seen fan cases with a circumferential hook machined into the case just forward of where the blade runs. The function of this hook is to catch the released blade and prevent it slicing off the intake as appears to have happened here. Does this fan case design have any feature for arresting the forward motion of the released fan blade?

armagnac2010 wrote:

......... The Southwest 737NG and that one would tend to indicate Boeing nacelles are weaker as they should be.

The "fan blade catcher" structure is still there.
( see images on the avherald site: https://avherald.com/h?article=4e35503b&opt=0

What came off is the outer aerodynamic inlet of the engine nacelle.
looks like under full load blades can have a distinctly forward trajectory when coming off.

Should the armored shroud reach further forward?

I would call for some careful thinking before dismissing fairing damage as a non-event. The discussion here basically went along the lines of "not so dangerous, because it is not the hull", so "nothing to see here". But we don't yet know what hit the fairing. We also don't know what damage it did behind the fairing, or if it also damaged the wing even before hitting the fairing. And most importantly, we don't know what it would have done to the fuselage, if it did hit it and not happen to impact the fairing.

NTSB seems to be saying nothing exited the engine casing. I trust them, but I wonder if that covers the potential front exit, and having whatever sliced that inlet hit the fairing.

At the very least, as Rev pointed out, some re-assessment of the failure modes seems in order. Or, potentially some high energy pieces exited. Or maybe not. The point is, analyse first, get all the data, and only then make declarations about the significance of the events or lack thereof.

It seems the Japanese pulled the plug on those engines, after that the FAA and Boeing.

DenverBrian wrote:

Interesting that the fan shroud/ring cowling is intact...except for a diagonal slice through it. I've seen speculation from a UA pilot that this is evidence of a fan blade exiting forward, slicing through the ring, causing it to separate, and then leaving the entire rest of the cowling vulnerable to disintegration just from speed.

https://youtu.be/EwNCCrjMmeg

He is an AA 777 pilot.

The photo of the nacelle nose ring in that video does appear to be a slice.

NTSB says it was a contained failure.

A piece of a blade was in the engine and another on the soccer field.

This sounds like the speculation in the linked video is plausible - blade breaks, goes fwd, slices the nose of the nacelle, (and probably then goes into the wing fairing). Once the nose is sliced the entire engine nacelle comes apart.

Also noted in the video is that blade separation tests for engine certification occur with no fairing/nacelle.

PSU.DTW.SCE wrote:

N649DL wrote:

I wonder with the grounding of the PW 777s, does this mean UA's 763 and 764 are safe to back fill right now and not be stored? I know there were rumors that the 764s might be going away during COVID.

It would take months to reactive the B763 and B764s that are in storage, to prep for return to service, and get all maintenance checks up-to-date. It is not a small undertaking to return aircraft from storage in a short timeframe.

Its far easier both in time and cost to complete the emergency inspections over the next few days/weeks than to go down that route.

Right now, that's 24-28 UA 777s out of service. It sounds like the PW-based 777s are less reliable even compared to the existing UA 763 or 764. What will UA do if the pandemic subsides and needs additional metal and the PW-based frames keep this type of inconsistencies up? Use the Sh*tbox 739ER to HNL? Or pull PW 757s out of the desert? I doubt it at this point.

Seriously, what's the solution? They're likely going to be out for a while and that's a lot of aircraft to deal with regardless. It does seem like the PW 777s have been really run hard regardless of this incident (regardless of their interiors which are total crap as well.)

N649DL wrote:

PSU.DTW.SCE wrote:

N649DL wrote:

I wonder with the grounding of the PW 777s, does this mean UA's 763 and 764 are safe to back fill right now and not be stored? I know there were rumors that the 764s might be going away during COVID.

It would take months to reactive the B763 and B764s that are in storage, to prep for return to service, and get all maintenance checks up-to-date. It is not a small undertaking to return aircraft from storage in a short timeframe.

Its far easier both in time and cost to complete the emergency inspections over the next few days/weeks than to go down that route.

Right now, that's 24-28 UA 777s out of service. It sounds like the PW-based 777s are less reliable even compared to the existing UA 763 or 764. What will UA do if the pandemic subsides and needs additional metal and the PW-based frames keep this type of inconsistencies up? Use the Sh*tbox 739ER to HNL? Or pull PW 757s out of the desert? I doubt it at this point.

Seriously, what's the solution? They're likely going to be out for a while and that's a lot of aircraft to deal with regardless. It does seem like the PW 777s have been really run hard regardless of this incident (regardless of their interiors which are total crap as well.)

Not as hard as the ones in Japan on four to six legs daily.

Almost 400 posts and no one has asked the traditional A.net question, so I'll do the honours

Is it a write-off?

Jokes aside, and I am not trying to start a A vs B war here but recently we've had
- 3 incidents involving the 112 inch engine (2 UA + 1 JAL), all 772
- 1 incident involving the 94 inch engine (Longtail) 744BCF

So, statistically speaking, is an incident on the 100 inch engine fitted on the A330 just waiting to happen?

Did they remove the engine ringlet from that homeowners yard already? Is that it laying next to the engine on the ground in front of it? If so i'm shocked no one filmed its removal from the yard?

889091 wrote:

Is it a write-off?

I was quite old and the roof was caved in, so probably

Noshow wrote:

Did they recently change any maintenance procedure or similar?

or is it just the number of hours (aka just getting old)? all good questions to ask and ones that i am sure the NTSB will ask.

ordbosewr wrote:

Noshow wrote:

Did they recently change any maintenance procedure or similar?

or is it just the number of hours (aka just getting old)? all good questions to ask and ones that i am sure the NTSB will ask.

The basic idea in this area is to adequately have checks and maintenance arranged such that deterioration is detected before things come apart.
This seems to have not worked here?