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Boeing proposal to avoid 737-MAX wiring shift does not win U.S. support
- jlawer 7y agoNot an aircraft safety expert but I am curious if shifting the wires may not introduce more potential issues in existing planes, as the existing risk factor seems to be proven low (i.e. they are not requiring all 737-NG airframes to have the work) I would imagine there is a non-trivial risk of a worker introducing a higher risk factor (drilling a little too far, creating metal shavings, putting too much weight on a support). The rules were made for a reason, and Boeing should follow them. However I wonder if it would be safer to simply fine Boeing a similar cost to what the rectification would cost and grandfather it in for existing airframes. I am just glad there are people more qualified to make this decision.
- mjevans 7y agoMostly agree, however I think Boeing should be required to engineer an approved and deemed safe remedy by a panel of experts comprised of international regulatory engineering staff deemed to be experts in this field. The cost would be the greater of the approved solution or the envisioned cost of correctly re-working existing airlines. (The cost savings might come from a factor of cost not considered here, Boeing's liability to airlines for downtime of units or inability to sell new planes.)
- melq 7y agoI am also a non-expert, and am sympathetic to your argument, but I don’t think there’s any reason to believe that whatever fix is proposed wouldn’t account for the type of risks you are concerned about. All of the risks/concerns you mention would be relevant to any sort of mechanical work on an aircraft, and that is a field of engineering that on the whole has an impeccable record of safety and rigor. Again, not an expert, but from what I understand the issues with the 737 max were software/design related.
- scumbert 7y agoAnd (lack of) proper pilot training
- gonesilent 7y agoPart not talked about is the wires in question for the tail also offer redundancy. Boeing wanted to cut time on manufacturing ran them all along the same section of the tail.
- Piskvorrr 7y agoInteresting. I though that part was written in blood with https://en.wikipedia.org/wiki/United_Airlines_Flight_232 https://en.wikipedia.org/wiki/United_Airlines_Flight_232 (uncontained engine failure has hit a SPOF in the tail section, severing all hydraulics)
- bronson 7y agoFeeding an automated system (with authority to crash the plane) from a single sensor is also known to be wrong. Controls engineering has taught failure modes and redundancy since the '60s. That didn't stop Boeing.
- rbanffy 7y agoBoeing wants to have a quick and cheap fix (no fix) and get a pass on international aviation norms based on the argument it's not "too unsafe" and that fixing it would risk making the 737 MAX fleet non-flightworthy. Well... It's not like it's flightworthy right now. If Boeing can't offer a fix that makes the plane flightworthy, then the airplanes should be scrapped. Remember we only are experiencing this because Boeing wanted a plane of the same type rating as the 737 NG and opted for that instead of a new design (that would be in accordance to all current safety norms, unlike the MAX) because it'd increase their profit. Two planes fell from the sky, killing everyone on board, for no other reason than Boeing wanting to increase its profits.
- onlyrealcuzzo 7y agoI thought the planes would be fine if Boeing just dropped the idea that they could be flown by pilots only trained to fly the 737. Is the plane not safe to fly in general AND it needs pilots trained to fly it specifically?
- rbanffy 7y agoIIRC, on a high AoA the lift generated by the larger engines moves the center of lift ahead of the center of gravity, making the plane unstable. This is what MCAS was arguably designed to prevent, forcing the plane behave like a 737 with smaller engines. Without MCAS, this would be a crappy experience for the pilots, but, with proper training, they'd be able to fly it just like you and me can safely drive cars like a Reliant Robin (just never think about hitting the brakes in a curve). If you feel the plane wanting to point up a bit too enthusiastically, you can push the stick forward (or adjust the trim) and make it more cooperative. It just turns out that, with MCAS, little training, and a defective AoA sensor, the experience was lethally crappy.
- foldr 7y ago>lift generated by the larger engines moves the center of lift ahead of the center of gravity Do you have a reliable source for the center of lift behind CoG shift? I've not seen that claim before.
- zymhan 7y agoThis is definitely a concern. Having to undo so much of the wiring could introduce the risk of some of the insulator breaking on other wires, or accidental damage or something else. But the FAA would definitely weigh this against the possible issues of high-voltage wires running in the same bundle as control wires.
- cptskippy 7y ago> Not an aircraft safety expert but I am curious if shifting the wires may not introduce more potential issues in existing planes, as the existing risk factor seems to be proven low (i.e. they are not requiring all 737-NG airframes to have the work) The 737-NG was introduced in 1997, one year before the new regulations went into effect so it's grandfathered in. Seeking to have the 737-NG retrofitted would be like requiring all cars without airbags to be retrofitted. What Boeing did with the 737-Max through out it's certification process was argue that it was so similar to the 737-NG that it should be grandfathered into certifications as well. This is done in a lot of industries where certification or regulatory approval is costly and complex, regulators offer a Me-Too path to certification where you argue that your product is based upon or similar enough to an existing product that only the differences need scrutiny. By going this route, Boeing was able to avoid redesign and retooling for things like the wiring harnesses which saved cost and time to market. Now that the 737-Max is having to be re-certified, AND Boeing's delegated authority to self-certify has been revoked, the FAA is going over everything. The wiring harnesses which were Me-Too'd, aren't in compliance with 1998 requirements. Boeing is trying to argue that the 737-NG has proven the design safe and thus the new requirements shouldn't apply.
- droithomme 7y agoGood.
- cletus 7y agoOne wonders if the problem of the MAX won't be effectively solved by the Covid-19 triggered recession. With people flying less, it's a pretty good reason to cut aircraft orders, no? At some point the 737 gravy train was going to end. There's only so long you can maintain the same type rating on a traditional (ie not fly-by-wire) plane where you eventually want to change the handling (as the MAX did by putting on large engines and moving them to compensate). So those who made the decision to go with the MAX rather than the engineer-favoured solution of a complete redesign (because the MAX was going to be ~2 years faster to market and have a captive market of 737 type rating airlines like Southwest) are ruing that decision. Or at least if they hadn't collected huge bonuses for years and were in any way held accountable for a bad call, which sadly they are not.
- WalterBright 7y agoThere's nothing wrong with the concept of MCAS. Just it's implementation.
- ljm 7y agoIts implementation and the corporate culture that pushed for that. Just as there's nothing wrong with communism, just the Soviet Union's implementation.
- chriscatoya 7y agoAside from the gallon of blood and pound of flesh we'll see called for in the public/political arena, I really doubt there's any viable fix that won't require pilot training. As I understand, the 737-MAX blunder is at the core a result of bad incentive alignment baked into their deal with Southwest: Boeing was trying to avoid any FAA "differences" simulator training requirements to make more money in a fleet sales order to Southwest Airlines. If the FAA required level-D simulator training, Boeing agreed to rebate Southwest $1 million for each MAX bought. The training would have cost Southwest $2000 per head. That's $18M for their 9,000 pilots. source: https://newrepublic.com/article/154944/boeing-737-max-investigation-indonesia-lion-air-ethiopian-airlines-managerial-revolution?utm_source=pocket-newtab https://newrepublic.com/article/154944/boeing-737-max-invest...
- tyingq 7y agoList price for a single MAX8 is $120M. I'd be surprised if $18M total of upside was the primary driver across an initial qty 40 aircraft order. They could have just offered that as an additional discount.
- NikkiA 7y agoThe 737-MAX800 is something like $10M more than a A321-NEO, when the A321-NEO meant retraining your pilots and the 737 didn't, that $10M difference closed a lot, now both are going to require retraining.
- rsynnott 7y agoThis is nothing to do with the MAX's inappropriate affection for the ground; it's a separate safety issue.
- vinceguidry 7y agoIt's not, separate, one drives the other. Their efforts to make the plane "identical" to the 737 in terms of training is what caused them to add these dangerous "features." It's really quite amazing.
- ggm 7y agoWe aren't only arguing about how much money is going to have to be spent, we're arguing about how the money is going to come from shareholders, or customers, or passengers, or the tax payer. If you think this isn't an argument about money and who pays, I think you misunderstand why we are here. There is no other reason we are here, than money. An unwillingness to incur cost, or cause customers to incur cost, that made other choices of provider more attractive drove Boeing to make decisions which now will cost money, to them, to the customer, and probably to everyone else at large. Boeing is not in pursuit of the "best" fix, its in pursuit of the "least worst (in cost terms) fix"
- lithos 7y agoBoeing looks more lika a petulant child that got caught cheating on their chores. That then got caught cheating on those same chores enough times in the same day, that their parents needed to get a chair and watch them complete them.
- jl6 7y agoTangentially, I believe the root cause of all software architecture debates is an argument over who pays what aspect of cost. Language goals such as expressivity, readability, brevity, composability; and features such as static typing; and patterns such as monoliths and microservices, ship-fast-fix-later, agile and waterfall design, centralized vs distributed; and aphorisms such as DRY and YAGNI - can be evaluated in the framework of shifting cost between original programmer, future maintainer, service provider, service user, or library/module reuser (and one individual may assume all of those roles at different points in the software’s lifecycle!).
- code4tee 7y agoBoeing’s argument is that the issue really isn’t an issue based on available data. The FAA’s argument is that a rule is a rule and Boeing seems to have a problem following the rules. Boeing is probably right but given the mess they got themselves in it’s probably best to just fall in line and follow the rules. They’re not helping their cause trying to apply logic here.
- bkor 7y ago> Boeing is probably right From the article: "New safety rules on wiring were adopted in the aftermath of the 1998 Swiss Air 111 crash." These recommendations were added as a result of a crash. The crash happened a bit after the 737NG started flying (AFAICS 737NG=1997), so I guess existing certified aircrafts didn't need to be modified. It does make sense for a new aircraft though.
- CivBase 7y agoDoes saving face mean nothing to Boeing? Wont this kind of behavior decrease Boeing sales as the public continues to loose confidence in their planes? At this point just do it. Do anything to at least appear like you're taking the matter seriously. Just let the regulators have their way for a while. Surely it's better to just take the short term hit. I know the stock market doesn't generally reward short term sacrifices for long term gains, but does public image really mean this little anymore?
- rjsw 7y agoOne factor that could be important here is that one CAD exchange standard doesn't currently do a very good job of modelling wiring harnesses. This problem first showed up on the A380 when different CATIA versions were being used at the two Airbus design centres. A solution is being worked on by a joint Boeing and Airbus group but will be a while before it is published.