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How were these not noticed in proper inspections? Is this the first time these planes have been inspected?
by dataflow 3y ago
How were these not noticed in proper inspections? Is this the first time these planes have been inspected?
- Kluggy 3y agoThey generally don't disassemble the entire plane every time they get inspected...
- dataflow 3y agoThis required a full disassembly to be noticed?
- janice1999 3y agoThey do disassemble the entire plane for heavy maintenance checks every 6-12 years. The MAX 9 has been in operation for just a few weeks though...
- 0cf8612b2e1e 3y agoThat’s pretty incredible. After a heavy maintenance breakdown, what percentage of the plane gets replaced? Or is everything already on a routine maintenance schedule so the intention is to visually identify unexpectedly failing parts?
- HPsquared 3y agoProbably still not every single sub-sub-sub-component.
- iancmceachern 3y agoThings like fasteners all get replaced, other things get replaced or refurbished on defined schedules.
- jupp0r 3y agoIIRC every bolt's torque value needs to be logged any time it's (re)fastened. At least that's true for aircraft engine maintenance, not sure if it applies to the assembly process of the airframe, I'd sure hope so!
- SketchySeaBeast 3y agoMan, if that's not automated how do they keep the numbers from being fudged? That's a lot of bolts, isn't it?
- avn2109 3y agoMost of the fasteners on the airframe are probably not bolts, e.g. rivets on aluminum airframes. But yes it's surely still a lot of bolts.
- kube-system 3y agoI'm not sure what the standard is in the aviation industry, but things like data-logging torque wrenches exist, and are used in other industrial applications.
- gafferongames 3y agoThey should put the bolt torque values on the blockchain. That'll fix it.
- sparky_z 3y agoWhich doesn't rule out, say, a design flaw that allows the bolt to loosen over time under certain circumstances.
- ryandrake 3y agoThat's why we have safety wire, which is all over aviation construction.
- spaceywilly 3y agoThe Max 9 has been in service since 2018 though, I think if it was a design issue it would have occurred before now. This seems like a Manufacturing QA “escape” to me. Some bolt was either not installed properly or not tightened to the proper spec, QA did not catch it
- gnopgnip 3y agoShouldn't the bolts be safety wired after being torqued?
- heads 3y agoDoes wiring bolts actually help? I feel like if a bolt is going to come loose enough such that the wire is all that is holding it in then you have a big problem already. The wire is just delaying the inevitable. A bolt is either fastened or it isn’t. If the wire is all that’s left to hold it, then it isn’t fastened and your parts are being held together with a very weak piece of wire.
- RandallBrown 3y agoThe wire is supposed to prevent the bolt from becoming loose.
- kube-system 3y agoThe wire or pin doesn't support any of the load. It is there to prevent any vibration from allowing a nut or bolt to rotate. https://fastenerengineering.com/what-is-a-castellated-nut-and-where-is-it-used/ https://fastenerengineering.com/what-is-a-castellated-nut-an...
- HPsquared 3y agoThe safety wire comes in to prevent a loose bolt from gently unscrewing itself further and completely disassembling itself (which can happen with vibration). You're much better off with a loose bolt, than a missing one. It'll hopefully make itself known somehow (maybe even just visual inspection) while still remaining somewhat attached, which is better than nothing.
- heads 3y agoThanks for the explanation. Does that mean a correctly wired bold should have wires loose enough to allow a loose bolt to give itself away — either through rattling or becoming visibly undone? When I searched for images of wired bolts just now I saw many examples where the wire is done up quite tightly, which doesn’t seem right.
- exabrial 3y agoPrecisely... everyone other "expert" on HN is asking the wrong questions
- rabuse 3y agoHot take, but I'll bet this will become more epidemic as companies hire more for quotas rather than merit like they used to.
- krisoft 3y ago> Is this the first time these planes have been inspected? Most likely weren't checked since the planes left the factory yes. To quote from: https://theaircurrent.com/feed/dispatches/united-finds-loose-bolts-on-plug-doors-during-737-max-9-inspections/ https://theaircurrent.com/feed/dispatches/united-finds-loose... "The five aircraft were delivered to United between November 2022 and September 2023, according to ch-aviation, and would likely not have been through a heavy maintenance C check that occurs every 4,000 to 6,000 hours or two to three years."