This is a panel with about 36 screw fasteners. It is not a quickly removable panel therefore not removed during line maintenance. What lies behind it I wonder.
Got to be maintenance error although I don't have any 777 familiarity, I do have a few other types in 36 years LAE.

Maybe if the bracket cracked through the screw holes? Or through some of them and then the rest of the screws broke or pulled out? I'm not really even convincing myself, though.

there is always the possibility that the screws were in place and unscrewed by themselves due to undamped vibrations stemming from another supporting bracket that failed.

but gee gosh why are we pursuing this in R&N ?

Unbelievable to see that some of you are stretching this discussion.

I told you what the reason was for the departing panel. If you don't believe this be my guest. But know this that it's complete nonsens to say it's a mx error.

KLM is not to blame.

Maybe a schock to ya'll but things can break on aircraft, It is not immediate human error.

I think we need to extend the discussion at least to the point where we understand your report.
So far, all you have said is that there is bracket that commonly fails. Presumably one that is holding this panel in place. If that is the only information you have, I would not conclude that a bracket failure was the immediate cause of the panel separation - because all of the screws are missing. Although I might guess that a bracket problem triggered the maintenance that left the panel with most or all of its screws missing.

But you seem to be convinced otherwise, and perhaps justly so. That would mean that you have other evidence that you have not shared. Perhaps you have seen other photos, or the bracket itself, or you know some other detail of the previous panel bracket issues.

Whatever it is, can you fill us in? At least in broad terms? Otherwise we are left with your assertion and the suspicion that you are misinterpreting whatever that additional evidence is.

@ErwinS - I have no cause to doubt what you say and think that it is said with the best intentions. But would like to add that the JTSB will most likely stretch a discussion like this into an independent Incident Report. It is not for the airline or maintenance organization, nor the manufacturer, to have the final say in what happened and why.

What surprises me and a number of others in this thread is, that on the photos that we have there is hardly any visible damage and the are no (bend or sheared) bolts or other tears or fragments. So what was the detachment sequence? Did the flight crew register it?

It put me on the track of thinking about what would be the difference in damage between hinged-panels (with failing latches) and non-hinged bolted-panels. In this case it looks like the panel popped or blew straight outward and did not hit the fuselage or any surfaces. Sounds special. And if it happened like that you could wonder if a pilot would be able to notice anything at all.

In another case of an 777, a hinged ADU-door of about 70lbs, detaching at 6,000ft, the pilots only felt a light shudder. And only investigated when the cabin crew reported something hitting the fuselage. They found the fuselage was penetrated and the plane dumped fuel and returned.
In that case the plane had only just left maintenance and was inspected a number of times, but the investigation concluded that only 1 of 13 latches had been closed properly. The probability of missing a countersunk bolthead is lower I guess than missing a latch.

So not stretching the discussion but interested in more facts.

The bracket failure will be that of the bracket that supported the screws box in the store room - thus leaving no screws to fit.

Or any other regular failure will be covered by a AD or SB by now or a grounding of type.

Or that is what happens in the real World.

okay Erwin, I couldnt find any images that showed the back fairing, but there is one of the front, so it is probably similar?

https://i.imgur.com/iSRu3Fv.jpg

As many others have noted, the bracket seems like if it cracked or broke, at least some of the fasteners from either the bracket, or the attachment to the other panels, and even part of some bracket attached...it does seem very odd that there are no fasteners, no bracket, and really no evidence of any pulled through the fairing.

Since this failure did land in an urban area and cause damage, we are all going to find out anyways...

Cant believe we have 3 pages about a lost panel..:uhoh:

The reason why this panel separates is that the support bracket design isn't rigid enough to stop the panel from vibrating and that leads to the screws migrating out. Its not unusual to see screws on a turnaround that have started to migrate out and this can be exacerbated by having worn anchor nuts or incorrect length screws - that being said I have seen this panel lost on a newish aircraft from Boeing that hadn't been through base maintenance and had never had that panel removed during airline service.

I don't know if this adds to the discussion at all; the incidents could be unrelated and I haven't found any news so far about investigation details but..

Earlier this month an ANA 767 based out of RJAA (If I remember right) lost a panel TWICE. I thought it was bad Chinese maintenance when I read about the 767 as it had been flying out of a Chinese airport, but now who knows. Of course it could just be a coincidence. Lost the panel on one flight, landed safely at destination, had panel replaced and then it came off again in flight. Both times landed without incident but I don't have details on what the butcher's bill was re: airframe damage.

Three panels, same airport (different companies) in the space of a month - could be unlucky coincidence but it is worth checking out the maintenance procedures as well as preflight procedures. Everyone be vigilant on your walkarounds. Hard to spot missing screws on the ground but do your best.. Maybe walkarounds with the 20something year old flight attendants with their eagle eyes would be a nice diversion from the normal :D

Could be to do with the fact that we've been presented with several conflicting theories, yours included.

And just now (08:00 GMT), BBC are reporting a 767 lost a panel weighing 3Kgs while flying over Japan. Is it panel shedding season in Asia?

I've been working the 777 in line maintenance for almost 20 years. I've never seen or heard of an issue with that panel or that area. The hydraulic ADP access panel that came off a BA 777 some years ago is the only significant one that springs to mind.

Well that certainly matches what we see in the photo.
However, I wouldn't expect the conversation to end with everyone accepting the notion that a panel falling off a plane is to be expected.

Lots of alternative explanations match what we see in the photo, some more feasible than others.

My favourite one involves a fairy with a screwdriver.

As I said, look it up on myboeingfleet - plenty of discussion there in the forum.

Its not expected, just not unknown. I dont know what the rate of failure is but like everything else on an aeroplane below a certain percentage then the failure rate is acceptable. To re-engineer the brackets and make them more secure would involve putting the panel fasteners though the skin and then you get into yet another load of stress calculations and possible redesigns of the skin panels. Is all that cost worthwhile for an incident that maybe reoccurs once every 2 - 3 years?

It depends on what it hits and where it ends up.
At least there aren't any more SSTs to take out. In that case, it was a wear strip that had fallen from a Continental flight.

Well that was more down to Air France than anything falling off an aeroplane.

Everything in aviation is based on cost-benefit, would it be cheaper to re-engineer the aircraft or live with this pretty rare issue and try to mitigate it?.

no wonder it looks like fresh paint.

If vibration is causing the screws to loosen, I still think it is surprising that it happened to all two dozen of them at once. But isn't Loctite a simple solution?

I hope that Japan invoices Boeing for tax on that thing at a rate of 220%.

It's not clear from some fuzzy pictures that all screws backed out. Some could have simply had their heads popped off from vibration. It happens to rivets like that.

Whatever the failure mode, it's clearly known by now as the aircraft in question went back into service yesterday.

It's only a matter of time before the details find their way into the public domain.

It appears to me that the panel is NOT part of the fuselage- pressurized section and is strictly/simply a fairing panel. And IMHO as such - a bit of locktite or application of almost any tacky damping material on the inside would suffice to dampen the ' vibration' problems. I find it hard to believe that all fasteners simply vibrated out a the same time.

Using Loctite would make removing the panel somewhat difficult....

From many of the posts, including mx people, this issue appears to be far from rare.

In this case, it landed in an urban environment, and smashed an occupied vehicle window. Could have easily hit a person. It took this long to elevate the issue, but luckily, so far, no loss of life, but certainly the potential is there.
The lazy B's nonchalant attitude to pieces falling off of aircraft for years is a bit concerning.

You really can't achieve reasonable freedom from risk (Safety) by assuming equal "what-ifs" without data to back them up. Breaking a windshield is minor and of course it missed hitting somebody on the head based on the area exposure vs occurrence loss rate

Parts that float to the ground under high windage loads have historically low risk of severe harm. Of course they are not acceptable occurrences and some level of control of the occurrence need be made. However I didn't think that this thread was about the adequacy of the repair incorporation

Not sure it isn't that rare - yes its a known problem with the 777 but given the amount in service and the flying hours that they are racking up, if this type of incident happens once a year then its not that big a deal.

You have to remember that most of the time this problem is caught before it progresses to panel loss - so if the Engineer spots loose screws on a turnround and retorques them it becomes a non-issue. The first panel loss I was involved in we highlighted the issue to Base Maintenance who then started to carry out a specific check on the screws on this panel at minor checks and also made sure that the Line guys were aware of the problem. That was over 10 years ago and the operator hasn't suffered another panel loss.

loma,

The part smashed a window on a vehicle. What would be the result of a human interface? Landing in a highly populated urban area? Couple that with a history of failures with apparently no sucess.

The reality is the number of instances where the panels have come off. It appears that sometime multiples in a single day, at ONE airport. According to mx personnel, this has been a problem for some time.

Liability, coupled with history of failure. Had the panel injured the occupants of the vehicle, either physically or mentally, the investigation would find that this was a known, recuring issue, that Boeing was very well aware of, and decided, for whatever reason, not to remedy, but simply to fix on occurance.
That equals $$$$$$$

No, I think you will find it is the way journalists work.

A thing happens, and the journos look at the 'wires' (24 hour news feeds from companies such as Reuters).

Because the 'thing' is fresh in their minds, they suddenly notice other occurrences of the same thing*, and report those too.

After writing a few stories, they get bored with that subject and move on.

Which is why things often seem to happen in threes, or as an 'outbreak' of similar events.




*which are actually happening all the time.

From the somewhat-fuzzy photo I showed earlier in this thread, it looks as though the head of the top left screw simply pulled through the panel - causing the hole to become enlarged. The next hole over is also enlarged, but not as much - so maybe that was one where the head of the screw was worn off. The other holes are smaller - consistent with screws vibrating loose.

So it would not appear that they all vibrated loose at the same time. What we see is consistent with the problem working its way to the top left of the panel. Then with only two screws left holding the panel, vibration was no longer an issue - one wore/sheered away from motion and the other just tore free.

I'm not saying that this is what happen, but it is a plausible scenario.

There's a link to a clearer version of the photo in my post #14.

I can't see any holes that look like a screw head has pulled through them.

FWIW a close look at two- three holes lower right above curb in photos- blue background- shows ' smoke' like traces typical of metal to metal rubbing- fretting, possibly indicating loose fasteners thru whatever bracket below- especially if bracket is aluminum alloy.

Most of the other fastener holes seem=- repeat seem to have paint in the countersink area ( reflections make it difficult to be sure ). had there been a vibration problem the paint would hav bee rubbed or flaked off exposing the bare material( aluminum or composite under the countersink. The panel may have been recently painted while held in place by only a few fasteners in the corners thus the edges of the panels -- appear-- repeat -- appear -- to have been freeshly painted also.

Just my .00002 cents worth having dealt with fastening issues- sealing issues- on both composites and metals and fatigue tests way too many moons ago

The photo I showed is from the one you linked to. I just rotated it to its upright position and cropped it to view that top edge.

To compare hole sizes, notice how much foliage and brick shows through that top left hole. It looks wide enough to pass the head of a screw - at least given one that had been partially loosened with vibration and allow to bend slightly.

I'd be interested to know how a relatively small light alloy panel could exert enough force on a screw to bend it.

Isn't that panel made of composite (eg fibreglass honeycomb) material?

TOKYO
A panel weighing three kilograms fell from a plane onto a factory near Tokyo, Japanese officials said Thursday, the country's second case in a week after a similar part landed on a car.

No injuries were reported after the panel was discovered inside the factory near Narita Airport in Chiba Prefecture, a spokesman for All Nippon Airways told AFP.

"After consulting with a panel manufacturer, we identified that the panel was one that fell from our plane," a Boeing 767 flying from the southeastern Chinese city of Amoi, said the spokesman, Hiroyuki Miyagawa.

The panel was used as a cover for the emergency slide and ANA said a faulty bottle containing nitrogen gas was to blame.

The nitrogen is used to blow the panel off the plane, allowing the slide to deploy in an emergency but the bottle leaked, the spokesman said, adding it had since been replaced, and apologising.

https://i1.ytimg.com/vi/s8-393NFKww/sddefault.jpg


HPG blows a panel for the slide off the side of the ac, and no one is aware of it? After calling Boeing, Oh hey, look, that was from one of our planes? Walking around the ac, no one notices a piece that big missing with a big yellow cargo slide showing?

That makes 4 panel incidents within the space of a month for aircraft flying out of or to Japan.

It seems to me that this has got to be more than a coincidence. Someone needs to audit the maintenance being conducted in Japan. 4 panels in a month is a public safety threat - Tokyo is EXTREMELY densely populated, it is a miracle that this did not kill somebody.