Crisis over The Atlantic: The near crash of Air Transat flight 236

Re:Crisis over The Atlantic: The near crash of Air Transat f... by bambax on Tuesday January 10, 2023 @07:30AM (#34323825)

> But maintenance people in aviation aren't really ever exercising those creative problem solving skills

This is the opposite of what happened. The engineers were confronted with a novel and unexpected problem, and instead of following procedure (which they lack access to) they applied "creative problem solving skills". From TFA:

> Although it was possible to install the post-SB fuel lines and hydraulic pump with a pre-SB hydraulic tube, the tube would rest against one of the fuel lines at a point where it rounded a 90-degree bend close to the pump. Aware that the plane could not be dispatched unless there was clearance between the tubes, the technicians torqued a nut on the end of the hydraulic tube until it rose approximately 0.635 mm off the face of the fuel line.

Torquing a nut so that the hydraulic tube isn't technically rubbing against the fuel line is pretty creative and seems to solve the problem. But it didn't take into account pressure and vibration while in flight, and almost caused the death of 306 people.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by iso1631 on Tuesday January 10, 2023 @08:38AM (#34324656)

I'm amazed they can measure the distance between two real non-fixed components down to a few micrometers (they wrote 0.635mm, implying somewhere between 630um and 640um)

If 0.635mm (an odd number itself which happens to be exactly 1/40th of an inch, or "25 thous" in American sizes) and they let it go that sounds really odd. That's literally the size of a grain of sand. If the concern is rubbing, sure that implies it will move during flight.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by bambax on Tuesday January 10, 2023 @08:47AM (#34324767)

0.635 mm is indeed an odd number. The thickness of a piece of 80gsm paper is 0.065 mm, so maybe what is meant is "about the thickness of ten sheets of paper"...?

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by jamincan on Tuesday January 10, 2023 @11:23AM (#34327231)

It's precisely 0.025 inches.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by intrasight on Tuesday January 10, 2023 @01:55PM (#34329640)

Who else thinks that if a tolerance of the thickness of a sheet of paper, in a mechanic/maintenance setting, could cause the death of over 300 people, that there's a striking lack of fault-tolerance in the design.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by plasticchris on Tuesday January 10, 2023 @08:48AM (#34324780)

It sounds to me like they stuck a machinists shim in there, effectively a bit of precisely measured metal.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by nick889996544 on Tuesday January 10, 2023 @10:00AM (#34325809)

Shim feeler gauges would be readily available in most shops checking wear on moving parts. 0.0025 inches (0.635mm) was included in the first high quality (gearwrench brand) set that I looked up online.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by mrguyorama on Tuesday January 10, 2023 @09:38AM (#34325471)

Plane maintenance involves a lot of precise and specially designed tools.

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Re:Crisis over The Atlantic: The near crash of Air Transat f... by mannykannot on Tuesday January 10, 2023 @10:03AM (#34325872)

I wonder if this nut, if not every nut on an ETOPS airliner (or in general), has a specific torque value. If adjusting the torque can open up a gap, presumably doing so could close one as well.

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