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FAA issues emergency directive on 2,000 Boeing 737 NG, Classic planes
- benrrio 6y agoThe official PDF document is here: https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/ec0e5875b315e9e5862585ae007cd448/$FILE/2020-16-51_Emergency.pdf https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf... I always wondered what the proper terms was for an airplane crash, and now I know: "forced off-airport landing"
- rileyteige 6y agoNot necessarily. A "forced off-airport landing" could also be the result of an engine failure beyond gliding distance of an airport. Or engine fire, medical emergency in remote area, etc. There are many emergencies that could force an aircraft to the ground, off-field. Not all off-field landings result in an accident, or "crash". From our own regulations, NTSB 830 "NOTIFICATION AND REPORTING OF AIRCRAFT ACCIDENTS..." https://www.law.cornell.edu/cfr/text/49/830.2 https://www.law.cornell.edu/cfr/text/49/830.2 >Aircraft accident means an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage. For purposes of this part, the definition of “aircraft accident” includes “unmanned aircraft accident,” as defined herein. So while some off-field landings could be classified as an accident, that would only be the case if the off-field landing met the above definition.
- Sebb767 6y agoI think it would be rather hard to land a plane off the airport without substantial damage, especially when talking about larger ones.
- letitbeirie 6y agoI was thinking that too, but ditching a plane into water doesn't really count as a crash. Not sure it counts as a "landing" either, but hey...
- 0xffff2 6y agoFor small 4-6 seater general aviation aircraft it's hard (relative to a normal landing), but not at all unheard of. A modern 4 lane highway is more than wide enough, and very probably has a long enough straight section within range, to make for a relatively uneventful landing if you can get traffic to cooperate. You're absolutely correct though when it comes to larger aircraft. I rather doubt there are any examples of an off airport landing of a 737 without significant damage to the aircraft.
- FDSGSG 6y ago> I rather doubt there are any examples of an off airport landing of a 737 without significant damage to the aircraft. https://en.wikipedia.org/wiki/TACA_Flight_110 https://en.wikipedia.org/wiki/TACA_Flight_110
- throwaway0a5e 6y agoLooks like they had about 5000ft to work with. Not great, but not bad either. https://www.google.com/maps/place/30%C2%B001'52.7%22N+89%C2%B052'47.2%22W/@30.0367583,-89.9149426,12149m/data=!3m1!1e3!4m13!1m6!3m5!1s0x889e047b4357698d:0x79a028ce18b61608!2sNASA+Michoud+Assembly+Facility!8m2!3d30.0267712!4d-89.9168139!3m5!1s0x0:0x0!7e2!8m2!3d30.0313106!4d-89.8797685?hl=en https://www.google.com/maps/place/30%C2%B001'52.7%22N+89%C2%...
- 0xffff2 6y agoWell, I stand corrected. That's both surprising and an incredible feat of airmanship by the pilots! Since I love reading about these kinds of incidents and the best way to solve a problem is to claim it's impossible, I amend my claim to "I rather doubt there are two examples of an off airport landing of a 737 without significant damage to the aircraft." :)
- leeoniya 6y agoi also like crashing into a mountain: https://en.m.wikipedia.org/wiki/Controlled_flight_into_terrain https://en.m.wikipedia.org/wiki/Controlled_flight_into_terra... and in space flight: "off nominal"
- elil17 6y agoA forced off-airport landing is not a necessarily crash. It’s an action taken, usually because of engine failure or imminent engine failure, to mitigate risk to the occupants of the craft. The pilot acts with intention and glides or flys the craft to the ground. They slow the craft down enough to touch down safely. The incident could still be considered an accident if there’s damage to the structure of the plane or injury to passengers. In contrast, a crash could be a lot of things: two planes colliding on the tarmac, loss of wings, or a controlled flight into terrain (such as flying into the side of a mountain).
- FabHK 6y agoAnd you know the checklist for forced off-airport landings at night? 1. Airspeed - SET 2. Fuel Valve - OFF 3. At 100 ft: Landing Lights - ON 4. If you don't like what you see: Landing Lights - OFF
- leetrout 6y agoI have been wondering how dangerous flying is going to be when when / if it comes back and all these planes come out of storage. Mechanical things just sitting around is some times far worse than them being in constant use.
- deleted 6y ago[deleted]
- frakt0x90 6y agoYou still have to keep the aircraft's normal maintenance schedule even when it's in storage.
- KMag 6y agoThough, if the maintenance schedule items are mostly of the form "W needs to be inspected after X flight hours, Y landings, or Z days since last inspection", there's probably significantly less experience backing up the Z parameter.
- ponker 6y agoThere are three guidelines. Some are per flight, some are per operating hour, and some are per calendar time.
- tjohns 6y agoThere are manufacturer approved procedures for putting aircraft into long-term storage, as well as returning them back to service. Yes, there is absolutely additional wear that happens just from sitting around. Repairing this (if necessary) is part of the return-to-service procedure.
- dehrmann 6y agoLuckily, this is already pretty standard practice for airplanes. I worry a little more about theme parks that don't do winter shutdowns or might not have done the full shut it down for the winter procedure with sudden lockdown orders. The regulatory environment is also sketchier.
- tyingq 6y agoThis only applies to aircraft coming out of storage, so it's not going to create a disruption.
- wwv25 6y agoOne of the inspection checklist items: Measure the clearance between the flapper bushings at both locations on each engine bleed air 5th stage check valve. If the clearance between the flapper bushings is a minimum of 0.004 inch (0.102 mm) at both locations, the engine bleed air 5th stage check valve at that location has passed this inspection. I knew that aviation engineering dealt with tight tolerances, but boy, it must be difficult to make a call like that when you're dealing with thousandths of an inch. Do field technicians have dependable tools and methods of measuring with such high degrees of precision?
- McDev 6y agoI supposed they'd be using something like this: https://en.m.wikipedia.org/wiki/Micrometre https://en.m.wikipedia.org/wiki/Micrometre
- rileyteige 6y agoyou mean https://en.m.wikipedia.org/wiki/Micrometer https://en.m.wikipedia.org/wiki/Micrometer ?
- ethagknight 6y agoIs that just being able to slide a piece of thick paper into the gap?
- tesseract 6y agoOr a "feeler gauge" meaning basically a 0.004in thick piece of spring steel.
- deleted 6y ago[deleted]
- juskrey 6y ago0.1 mm is a pocket calipers grade tool. Of course they have better ones but nothing extraordinary I think
- raverbashing 6y agoThat is surprising. Pandemic or no pandemic, you have NGs and classics going and coming out of storage with a certain frequency. Funny this wasn't found before.
- jschwartzi 6y agoI think it wasn’t an issue before because most airlines aren’t going to keep a plane they have in storage for multiple days. They’ll sell it to another airline. Otherwise they still have to maintain it and pay storage fees plus whatever lease or finance costs are associated with the plane. Boeing runs a finance corporation which is how a lot of planes are “sold.” They have to plan for maintenance windows and unexpected failures but when your fleet is big enough these events are regular enough that you can tune your fleet size to absorb these events without needing idle capacity.
- kenny11 6y agoThis is also why planes out of use for extended periods are typically stored in dry, desert climates - less moisture in the air to cause corrosion. The massive increase in stored aircraft due to the pandemic meant that there wasn't enough room at these airports, and so aircraft had to be stored anywhere there was space available, often in less than ideal climates.
- JanSolo 6y agoInteresting that the vast majority of 737s were flying so frequently that this was not found earlier. For their entire 20-ish year service life, those planes are never left idle long enough for this part to rust! Amazing. Goes to show how popular and successful the 737 line is.
- CydeWeys 6y agoThis is true of all airplanes, not just the 737. They're so expensive that they all need to be in use continuously.
- JanSolo 6y agoYeah I'm sure most commercial airliners are the same. Apart from maybe the Super-Heavies; I hear that there are dozens (hundreds?) of 747s and A380s sitting around doing nothing currently because they're too expensive to fly.
- CydeWeys 6y agoThose 747s and A380s are only sitting around not flying because of the pandemic. And it seems likely that many of them will never return to flight again at this point, except maybe after being modified for cargo hauling. Prior to the pandemic, if you had a flight-worthy plane of any size, you were using it continuously. Once a plane was no longer being used continuously it was likely about to be permanently retired.
- matt-attack 6y agoAnd this may be obvious to some, but why does use inhibit rust?
- t0mas88 6y agoIn normal use these valves take air out of the turbine stage, so they see very very hot air with almost zero moisture in it in normal use. If you park them long enough I can imagine they get wet from rain or even just condensation.
- cameron_b 6y agoThis, coupled with the idea that big planes simply aren't flying enough to keep the pilots certified has me concerned about commercial aviation. The scale-down and scale-up is incredibly costly and will result in huge write-offs of equipment that cannot be cost-effectively kept up. You can't just park these airframes and expect them to be ready when you need them.
- MrBuddyCasino 6y agoThis may be a dumb question, but why use materials that can corrode on such an important part? Just use stainless steel (or AL or TI), problem solved?
- enraged_camel 6y agoExplain that to the MBAs and bean-counters who are in charge over at Boeing.
- perardi 6y agoI’m guessing some other parameter was more important. Thermal expansion characteristics, ease of tooling, interactions with the materials around it, resistance to some other non-oxidative chemical corrosion…
- benhurmarcel 6y agoThis particular valve sees temperatures above 600°C. You basically need to use steel or inconel.
- AceyMan 6y agobearings and bushings need to be hard to resist wear and maintain their dimensions. Stainless steels hard enough for the job are too brittle and those other metals (Al, Ti) aren't even close to the hardness of any category of steel.
- bluGill 6y agoStainless doesn't corrode, but it tends to corrode any other metal it touches. Depends on alloys and a bunch of other factors, but all stainless isn't the answer either.
- jefftk 6y agoThe title here should have "737 NG, Classic" not "737 NG Classic". As in "Boeing 737 NG and Classic aircraft", not "Boeing 737 NG Classic aircraft".
- abrowne 6y agoOr even more clearly, "Boeing 737 NG and 737 Classic", since it wasn't obvious to me that they're all 737 variants.
- Contax 6y agoAnd why not just "NG and Classic"? Really curious, I see this replacement of "and" for a comma in a lot on headlines, and I don't know why or where it comes from (English is not my first language). Is there a name for this?
- mmanfrin 6y agoMost english speakers also wouldn't be familiar with the term, but it is called 'Headlinese'. https://en.wikipedia.org/wiki/Headline#Headlinese https://en.wikipedia.org/wiki/Headline#Headlinese
- myself248 6y agoAnd it's dumb. We're not setting hot lead into column inches anymore.
- azernik 6y agoBut we are trying to fit summaries into a limited screen real estate
- acheron 6y agoImitating this style is a good chunk of the Onion's humor. E.g., "Congress Approves $4 Billion For Bread, Circuses" https://politics.theonion.com/congress-approves-4-billion-for-bread-circuses-1819565262 https://politics.theonion.com/congress-approves-4-billion-fo...
- jacquesm 6y agoAnything mechanical that you don't use is on the way out, airplanes, cars it doesn't matter. Use it or lose it very much applies and all it takes is to not use something for a while to find completely new failure modes. Case in point, and very timely: just today I had to replace the valve that allows for the pressurization of the fuel tank on my car simply because it wasn't used for three months. It had seized and no amount of brake fluid or other solvents would get rid of the gunk enough to unstuck the valve so it could be worked.
- meristem 6y agoAircraft are meant to be in high usage, so decreased flight time and larger flight intervals will cause interesting problems. For example many part 135 planes currently parked need to be rolled to a different position daily because parked weight deforms tyres.
- WalterBright 6y agoYour car will also start exhibiting random failures if you leave it parked long enough. Parts will corrode, stick, develop flat spots, cold weld themselves together, water gets in, bugs and mice set up shop, chew on the wires, etc. Especially if you leave it out in the weather.
- deeblering4 6y agoAt the beginning of lockdowns I was wondering what might break down on the fleets of planes that have been grounded, or under utilized. I wonder what other bugs will be uncovered from not exercising machines that are designed to be used on a very regular basis.