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Comment by 1letterunixname | Hacker News Reader

Moral panic hysteria, but this is a non-story. Airbus came out to defend that that particular panel is held by a hundred plus fasteners.

Passengers should be concerned about shoddy bear straps on Boeing 737 NGs they can't see that were passed off as approved parts to make the production schedule. Boeing had the DOJ in their pocket making false statements about an ongoing NTSB investigation into AA 331 that broke up, likely due to substandard parts, when a 737 Classic would've likely remained intact in similar circumstances. 737 NGs are at variable unknown risk of breaking up on hard landings, runway overruns, and possibly even extreme turbulence. See also: Ducommun scandal.

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4 bolts missing, that gives all sorts of red flags. How would a passenger know the limit of number of bolts to be missing before failure? Or be sure other bolts are properly fastened after seeing missing ones? Calling off the flight is absolutely the correct decision.

No, it's hysteria. This is common practice on non-load-bearing access panels. I've seen many times on in-service commercial aircraft.

https://en.wikipedia.org/wiki/Normalization_of_deviance

Safety margins should be at their max before flight, I'm thankful engineers at Airbus put more bolts than required if they go missing mid flight, but before take-off it should be back at 100% safety margin.

No aircraft would ever fly then. You'd be surprised how much equipment on every single flight is inoperative or scheduled for deferred maintenance.

There's an engineered threshold at which an aircraft is deemed not airworthy. On airliners, this is managed through a Minimum Equipment List (MEL), which is a formal checklist that tells the crew which equipment is allowed to be broken (and for how long).

This threshold is less than 100% by design, because little things break all the time. It can take days/weeks in the shop to fix issues, so you need to batch up all the maintenance. (Can you imagine if you had to take every aircraft offline for several days after every flight?) And that's okay, because there's still a large safety margin built in as long as the MEL is followed.

> Can you imagine if you had to take every aircraft offline for several days after every flight?

That's exactly what the air force does. Most of their jets require tens of hours of maintenance for every flight hour!

Maybe when they are not used for their main purpose in full capacity.

When the authorities you've placed your trust in have demonstrated they're incapable of doing their job to keep you safe, it's normal to take that authority back into your own hands. It would only be hysteria if the Boeing incident hadn't indicated a systemic failure in the air-safety system.

> the authorities you've placed your trust in have demonstrated they're incapable of doing their job to keep you safe

Who has done that? One plane lost a plug, with no injuries. Who else has gotten even injured in a commercial US flight in the last year?

please. i'll take any odds that the vast majority of people on the plane are voluntarily flying for leisure. it's hysteria.

Every aircraft has some missing screws. Literally every aircraft. That's why there's so many of them.

Some of them matter, and the pilots keep a close eye on those during the preflight checks. Others, matter less so. (A single missing screw on a prop spinner - big problem. A missing screw on a non-structural plastic aerodynamic fairing - okay to defer, literally zero risk.)

I worked in aviation for years when I was younger, specifically around aircraft maintenance. If you think 4 missing bolts out of 150 are a red flag then I recommend you do not look at what has to happen for a plane to be deemed not airworthy.

The more pertinent question, for me, is where are those screws?

Are they on the ramp waiting to get ingested into an engine?

Are they jammed in the flap tracks?

Are they embedded into the leading edge of tail surface after flying off in flight at cruise speed?

Its one thing to say that you can fly without those screws on the MEL. Its a whole other thing for parts to be falling off of an airplane in operation, even if they aren't required.

A single piece of metal that fell off of a different airplane is what caused Concorde to crash.

How are those pertinent questions? Even with the answers, you (and I) would have no idea what we were talking about. The only pertinent question is: Do qualified mechanics certify that the plane is safe?

I’m a pilot, not an A&P, but I’ve seen what happens when a loose screw goes where it shouldn’t on an airframe. You should be very concerned about pieces of metal falling off of planes and going where they shouldn't. Its enough of a worry that just about every airport has procedures and a significant budget for managing FOD. Keeping screws (and other FOD) off the runway and taxiways is a multibillion dollar industry for a reason.

A non-required screw that backs itself off and falls off in flight is a maintenance procedures failure (torque or locking compound was ignored). Screws don’t just fall off. Ignoring it because it is non-required is dangerous because it could possibly indicate that screws are being installed incorrectly, including required ones.

Qualified mechanics certify every single non-experimental plane as safe. Yet somehow, planes still crash for mechanical reasons.

> You should be very concerned about pieces of metal falling off of planes and going where they shouldn't.

What kind of risk are we talking about? When did that last happen on a commercial airliner? How many people have been injured that I should be 'very concerned'?

As I mentioned before the Concorde crash is the most famous example of a piece of FOD from a plane causing a crash.

It’s a big enough issue that every airport is required to have a debris management program, and runways and taxiways are regularly swept by specialized equipment.

FOD is estimated to be a multibillion dollar problem by more than one study.

Right, but I don't need to be 'very concerned'; the airline industry is very effective at preventing it.

If I was going to be 'very concerned' about potential risks without considering mitigation, there's fuel tanks exploding, running out of fuel, drunk pilots, hitting mountains, runway collisions, etc. etc. Pieces of FOD don't seem to rate ...

My point is about risk, of course. FOD is not an effective risk to me.

Wikipedia: "Whilst taking off from Charles de Gaulle Airport, the aircraft ran over debris on the runway, causing a tyre to explode and disintegrate. Tyre fragments, launched upwards at great speed by the rapidly spinning wheel, violently struck the underside of the wing, damaging parts of the landing gear – thus preventing its retraction – and causing the integral fuel tank to rupture. Large amounts of fuel leaking from the rupture ignited, "

Concorde had decades of documented tyre problems. That was a flawed design (tyre and fuel tank) that allowed this crazy outcome.

You’ve chosen a very selective quote. What caused the tire to explode in such spectacular fashion?

It was a strip of metal that had fallen off of another airplane a few minutes before.

Concorde did have a higher risk due to its higher takeoff speed, but the only fatal accident in the airframes history was directly caused by a piece of metal that fell off a different plane.

> How would a passenger know the limit of number of bolts to be missing before failure?

They wouldn't. That's why passengers aren't tasked with being safety inspectors.

Totally. But then you would expect no action would be taken based on a passenger reporting something like this. That action was taken suggests that the passenger was the first person to observe something that was a serious enough risk to cancel the flight — and that’s what’s surprising and alarming here.

No, it suggests that the company was afraid it'd negatively affect their image if they'd fly anyway.

Every time there's some actual disaster on something like a commercial airliner, in the ensuing investigation it turns out there were tons of warning signs - missing bolts, ignored reports, etc. And then people, rightfully, go "why were all these warning signs ignored?"

And now here you are smugly telling us to ignore a bunch of missing bolts and that we're idiots for possibly thinking they could be indicative of a problem. Do you see how this is a big part of the answer to that perpetual question of "the signs were all there, why wasn't anything done?"

I have no horse in this race, but it’s possible that the answer to the first question of why were all the warning signs ignored is that there are a lot of trivial, spurious, or non-relevant reports, and no one retroactively looks at them in most cases because nothing happened. Upping the number of reports might make the problem worse.

In airframe maintenance this is rarely true. In theory you should be proactively dealing with these issues before they are report generating (in the sense of said reports remaining open a long time, all maintenance generates logs in planes). If an excess number of reports are being generated there is an underlying issue, like work is being deferred for profitability reasons, or the maintenance team is being rushed because they are falling far behind.

That tells how good people care about safety... Or do you think that it's planted evidence? ;-)

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