holycow 发表于 2019-3-17 11:53 8 R2 s1 c- b" f: a0 K今天西雅图时报的报道，Wow, just wow/ Y! j, v% i1 W9 n k2 ]4 ?
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https://www.seattletimes.com/business/boeing-aerospace/failed-c ...
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哇！好多信息是已知的，但这个上报0.6度实际2.5度太离谱了，这上法庭的时候，根本毫无辩解余地啊！% ?0 v; F2 u; }+ Z
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还好，波音补丁基本上按照我想象的，尤其是不容许反复否决飞行员的反否决。 . C/ a3 ?2 ^9 a; C5 @8 |2 R2 W4 ?" {; F1 U% i
狮航610在跑道滑跑的时候，左右迎角已经相差20度啊！这太TMD无语了！这地勤太太太……
Thoughts on Seattle Times article published Sunday morning Seattle time # }$ f* T. u$ o1 q5 O3 u ( r9 o1 E5 ]) d9 ^# tThis article is generally well written and seems quite accurate. One point of clarification is that early on in the 737MAX development it was thought that MCAS would only be needed at particularly high Mach numbers. For those conditions the prediction was that the original 0.6 degrees of MCAS stabilizer authority would be sufficient. That proved to be pretty close to the case during flight testing and the final MCAS increment size for cruise and higher Mach numbers is very close to 0.6 deg. Later on it was determined that MCAS would also be needed at lower Mach numbers. With that extension of MCAS came the MCAS authority vs. Mach number schedule that is in the current design. The high Mach end of that schedule is approximately 0.6 degrees. Only with Mach Number less than 0.4 is the MCAS authority 2.5 degrees. The larger authority at lower Mach numbers is needed as the effectiveness of the horizontal stabilizer is less at lower speed. It is quite common that flight control functions are given higher authority at lower airspeed and less authority at airspeed increases.
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1. 这个解释了scope creep的一部分原因 8 r' B0 @9 `; s2. 解释了包子那本看起来自相矛盾的波音手册是怎么来的：一部分是改变以前的文字，一部分是更改以后的说明9 Q6 T& ~: f+ }
3. Now if part of the fix is to limit stab trim, what about low mach scenario where that degree of trim was considered necessary?
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上面那个Boeing insider的帖子只说后来决定低速时也要MCAS，没说为什么。昨晚WSJ关于司法部调查波音的新闻里有这么一段：8 s$ d" `" {. S, h# x8 D
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But as the engineering effort and flight tests progressed, according to industry and FAA officials familiar with the process, the Boeing team saw the same feature as a potentially important safety net for a different hazard highlighted in previous crashes: lower-altitude stalls in which startled pilots mistakenly pulled back on the controls and sometimes crashed aircraft. FAA officials also recognized the potential benefits and approved the system as part of the overall MAX approval.
' N' G! D6 D; c % @+ {" |( H' H$ Y如果属实，纯属有些人聪明过头。这也解释了为什么fix要restrict authority, 突然间又不担心低速了
雷达卡
楼主
显身卡
发表于 2019-3-18 00:37:44
既然波音可以自己替自己安全检查，那要FAA干什么呢
