UA 433 loses part of exterior panel SFO-MFR
 

Lots of posts and news reports, most apparently containing false info about diversion and emergency landing, for UA 433 SFO-MFR, where post-landing inspection revealed a "lost panel". Try:
https://www.ktvu.com/news/united-air...-missing-panel
Not my area of expertise at all, but from the photo it looks to me as though most of the panel was torn off, some top part remaining. Given proximity to LG, could something have got caught on gear-up or more likely gear-down? No FOD found at MFR, but if due to conflict with gear, I'd be searching below the up/down locations once identified.

Over to the the knowledgeable...

B737-800, from 1998 ex Continental according airliners, Cannot judge the actual damage but the overall appearance around the missing panel indicates an aircraft rather poorly taken care of . if I compare it with a major European or Asian-Pacific airline.
Is this typical United standard of care or just an exception ?

Just heard of it, on a major Radio Station News in Germany.

And of course they mentioned the recent Alaska incident as "part of the fuselage came off leaving a hole" and that Boeing is already under observation.

The tone was not in a sensational style.

https://cimg8.ibsrv.net/gimg/pprune....9997f4c638.png
Screenshot from the article above and the Tweet embedded in it.

If the wing panel is anything to go by, I would say some duff fibre glass repairs. Water ingress, freezing/thawing cycle, loss of panel integrity, loss of panel. Have seen something similar on a leading edge panel with a botched repair, a heater mat was left on too long.

So airflow / pressure in behind might have blown it out?

Is that the flap drive mechanism I can see there?

From a news report:

Looks like the cover next to the slot where the landing gear unfolds. Landig gear strut visible in the top left corner. See this screenshot, taken from opposite perspective:

https://cimg3.ibsrv.net/gimg/pprune....b4101bf15c.png
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While Boeing is getting the FAA version of a colonoscopy, most of the incidents we've been reading about lately appear to be a result of poor maintenance at United Airlines. How worried should passengers be?

It's far more widespread than one airline or even one industry
Standards are dropping everywhere, Its what you get for decades of declining educational standards.

I've seen several reports that members of the US Congress are demanding that the United CEO appear before Congress and explain why United has been having so many recent incidents (not seen anything with regard to his response).

Meanwhile the MSM can continue to blame Boeing for there lousy design and built practices that allow bits to fall off 20+ year old aircraft that haven't been properly maintained.

Could we get Congress to appear before Congress and explain why they are doing such a crap job and trying to distract by getting CEOs on the hot seat?

strange, it appears that the rip was back to front (largest remaining pieces at the front)

It’s an odd dynamic that the American public accepts its elected representatives calling constituents before congress for a public browbeating. Not quite what the Founding Fathers had in mind.

If Kirby does appear, curious to know whether he will be wearing a suit or a dress.

Nothing but a fairing although the fastener heads are still secured implying fairing has been coming apart for some time. Clearly could have been flagged on a preflight .unless fairing condition is ignored in preflight. Agreed AC appears in ratty condition.

Can water forced by tires reach that area? It may just the photo but the fairing in front of the damage looks rather clean while the remains from the damaged area looks like it't gotten a sand and grit power wash. There's also what appears to be a hard scuffed area to the right side of the missing panel.

It could easily be some penetration that allowed water to enter, freeze, and expand to delaminate the part.

How dangerous is this departing panel? Material, mass... (regarding impact on some aircraft sections, people, ground equipment)?

Just another poor excuse to trigger the media and other vindictive frothers-at-the-mouth to launch into yet another anti-Boeing feeding frenzy, as if this has anything at all to do with Boeing...

What remains of the panel, in the photograph, appears to show that it is largely constructed from layers of either Carbon Fibre Reinforced Plastic (CFRP), or Glass Fibre Reinforced Plastic (GFRP), or possibly both, around a core of non-metallic honeycomb. These are common materials used in aircraft structures, and result in lighter weight parts, compared to, for example, a similar part skinned with aluminium alloy.

However, despite being relatively light, a fibre reinforced plastic and honeycomb piece, of the size suggested by the missing piece in the photo, falling from thousands of feet, likely spinning due to uneven aerodynamic forces, will certainly have the mass and capability to cause death or serious injury. Humans are soft and squishy, and the rough, broken edge of a falling, spinning piece like that could easily scythe into flesh. Quite apart from what being smacked on the head by the weight of the piece would do!

More solid, inorganic objects are also very likely to be damaged. 😉