B737 Max : CAA bans from UK airspace; Comair aircraft grounded
Mar 14, 2019, 2:15 am
#196
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Jackscrew operates the stabilisers. There was a famous crash in the US some years ago where the thread stripped off under excessive force and the stabilisers stopped operating. Result was the plane inverted and then nose dived. You can infer the final setting from the position of jackscrew in the actuator ring.
https://en.m.wikipedia.org/wiki/Alas...nes_Flight_261
https://en.m.wikipedia.org/wiki/Alas...nes_Flight_261
Mar 14, 2019, 2:26 am
#197
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Mar 14, 2019, 2:37 am
#198
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Maybe stop reading the thread, eh? It's making you all grumpy and unpleasant.
Otherwise you could explain exactly what is nonsense and why, which would be more constructive than taking supercilious sideswipes at other board members?
Otherwise you could explain exactly what is nonsense and why, which would be more constructive than taking supercilious sideswipes at other board members?
Mar 14, 2019, 3:48 am
#199
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Reading PPRuNe is an excellent way to gain insight into what Flight Simulator fans think the problem is, it's been a while since the first "P" in the name was appropriate.
Mar 14, 2019, 4:04 am
#200
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Well the middle point made by T8191 regarding the reason for this software module to counteract the tendency to pitch up is entirely correct. It is because of the increased thrust / repositioning of the engines this module is necessary on the MAX series. Period. Why the sneering agression?
Last edited by BOH; Mar 14, 2019 at 5:31 am Reason: Error in the pitch direction (thanks to Globaliser for the catch!)
Mar 14, 2019, 4:16 am
#201
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Correct me if I’m wrong but as I understand it MCAS is there to correct the aircraft from titling and therefore possibly stalling due to the engines. The engines are much bigger and placed further forward than previous design (smaller engines) and at full thrust the nose can drop so the MCAS steps in to prevent this through the stabilisers also(?).
If you weren’t joking and simply being a bit disrespectful to a generally interesting conversation then I would also suggest to stop reading the thread.
Mar 14, 2019, 5:08 am
#203
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Well the middle point made by T8191 regarding the reason for this software module to counteract the tendency to pitch down is entirely correct. It is because of the increased thrust / repositioning of the engines this module is necessary on the MAX series. Period. Why the sneering agression?
I have read the posts on the PPRuNe thread about an increasing tendency to pitch up as the stall approaches being caused by aerodynamic effects from the engine nacelles, rather than from pitch/power coupling, but I have no way of knowing whether those posts are accurate or not. There has, after all, also been reference to the Bournemouth 737 incident, which was some years ago and therefore not in a MAX. As others have said, there is no guarantee that anyone posting anything on PPRuNe has ever flown anything other than MS Flight Simulator, or perhaps not even anything more complex than a TV remote control switching to Air Crash Investigation.
Mar 14, 2019, 5:29 am
#204
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Isn't MCAS intended to counteract a tendency to pitch up, not down? If so, quote number one within DYKWIA's post would be plain wrong.
I have read the posts on the PPRuNe thread about an increasing tendency to pitch up as the stall approaches being caused by aerodynamic effects from the engine nacelles, rather than from pitch/power coupling, but I have no way of knowing whether those posts are accurate or not. There has, after all, also been reference to the Bournemouth 737 incident, which was some years ago and therefore not in a MAX. As others have said, there is no guarantee that anyone posting anything on PPRuNe has ever flown anything other than MS Flight Simulator, or perhaps not even anything more complex than a TV remote control switching to Air Crash Investigation.
I have read the posts on the PPRuNe thread about an increasing tendency to pitch up as the stall approaches being caused by aerodynamic effects from the engine nacelles, rather than from pitch/power coupling, but I have no way of knowing whether those posts are accurate or not. There has, after all, also been reference to the Bournemouth 737 incident, which was some years ago and therefore not in a MAX. As others have said, there is no guarantee that anyone posting anything on PPRuNe has ever flown anything other than MS Flight Simulator, or perhaps not even anything more complex than a TV remote control switching to Air Crash Investigation.
Mar 14, 2019, 5:45 am
#205
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Some of the actual pilots are dodgy too on pprune. The 'these kids can't fly' type. I doubt many pilots understand safety critical desiign either. So it's a mishmash. Like here for that matter.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
Mar 14, 2019, 5:54 am
#206
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Some of the actual pilots are dodgy too on pprune. The 'these kids can't fly' type. I doubt many pilots understand safety critical desiign either. So it's a mishmash. Like here for that matter.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
I do have a few hours in light aircraft [Civ and Mil], and an expired PPL, so I understand some of it! But I haven't had Flight Sim for many, many years.
Mar 14, 2019, 6:15 am
#207
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At least I can claim to have read all 1,359 posts, and have the ability to filter information, and have checked a few 'profiles'.
I do have a few hours in light aircraft [Civ and Mil], and an expired PPL, so I understand some of it! But I haven't had Flight Sim for many, many years.
I do have a few hours in light aircraft [Civ and Mil], and an expired PPL, so I understand some of it! But I haven't had Flight Sim for many, many years.
There is a large element of I know more than you on there. I’ll wait for the investigation outcome to be published.
Mar 14, 2019, 7:18 am
#209
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Some of the actual pilots are dodgy too on pprune. The 'these kids can't fly' type. I doubt many pilots understand safety critical desiign either. So it's a mishmash. Like here for that matter.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
There's enough though to hypothesise convincingly that a sensor failure close to the ground wasn't adequately mitigated by the software design.
Mar 14, 2019, 7:20 am
#210
Join Date: Mar 2004
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On Aviaton Herald they have the report on the Lion Air crash.
this paragraph may or may not be relavent:
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
...
The FAA says it anticipates mandating this software enhancement with an Airworthiness Directive (AD) no later than April. We have worked with the FAA in development of this software enhancement.
It is important to note that the FAA is not mandating any further action at this time, and the required actions in AD2018-23.5 continue to be appropriate.
this paragraph may or may not be relavent:
For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.
...
The FAA says it anticipates mandating this software enhancement with an Airworthiness Directive (AD) no later than April. We have worked with the FAA in development of this software enhancement.
It is important to note that the FAA is not mandating any further action at this time, and the required actions in AD2018-23.5 continue to be appropriate.