Software Wouldn't Fix Boeing's 'Faulty' Airframe
https://www.eetimes.com/document.asp?doc_id=1334482#
https://www.eetimes.com/document.asp?doc_id=1334482#
The problem is fault-tolerant design, not a 'Faulty' Airframe.The world has about 40 years of flying "unstable" aircraft since digital fly-by-wire was designed into aircraft in the late 1970's (e.g., F-117, B-2, just to name 2 examples). This is simply the commercial aircraft industry adopting it. So if one is surprised, they haven't been paying attention.
Notice that one thing pointedly lacking in his credentials is anything related to aeronautical engineering. Being an "experienced, instrument-rated pilot" (or having flown 757 simulators) hardly qualifies.Article written by Gregory Travis, a veteran software engineer and experienced, instrument-rated pilot.
True. But Boeing intentionally sold the modified 737 MAX as the same 737. They avoided having to retrain pilots for economic reasons.Notice that one thing pointedly lacking in his credentials is anything related to aeronautical engineering. Being an "experienced, instrument-rated pilot" (or having flown 757 simulators) hardly qualifies.
Many airlines are design with neutral stability and rely on augmentation systems to make them stable. Loss of those systems make the aircraft difficult to fly. Many military aircraft take that significantly further and are negatively stable and loss of the augmentation systems make them impossible to fly. It's been this way for decades. Small aircraft, like his Cessna, are positively stable and, in most situations, will recover themselves to a wings-level attitude if you just release the controls.
Economically, yes.If this true then it is the end of Boeing.
Who is they?True. But Boeing intentionally sold the modified 737 MAX as the same 737. They avoided having to retrain pilots for economic reasons.
Because the new MAX version of the 737 has heavier engines and other changes, Boeing added a system that under certain conditions of airspeed, CG location and weight, automatically moves the pitch trim to modify stick force. The pilot who is hand flying feels this as though he is pulling on the yoke and would naturally reduce pull force to lower the nose and angle of attack (AOA).
In the non-aviation media, this system is being called everything from new, to radical, to untested. In reality, nearly all airplanes larger than a basic four-seat piston single use some sort of device to alter the forces a pilot feels while maneuvering the airplane.
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What Boeing is doing is using the age-old concept of using the human pilots as a critical element of the system. Before fly-by-wire (FBW) came along, nearly all critical systems in all sizes of airplanes counted on the pilot to be a crucial part of the system operation.
The certification concept for relying on the human involves identification of a failure, and a reaction time. The way it works is that the pilot must be able to recognize the failure, then take three seconds to analyze what is wrong, and then take corrective action before the airplane flies into a critical condition.
Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.
The problem for Boeing, and maybe eventually all airplane designers, is that FBW avoids these issues. FBW removes the pilot as a critical part of the system and relies on multiple computers to handle failures.
- Allowing the MCAS system to generate so much downward trim that it couldn't be corrected by pulling up on the yoke.
- Not automatically disabling the MCAS when the pilot pulled up on the yoke.
Then why wasn't it the end of Boeing when there were multiple incidents (seven, I believe), including two crashes that killed everyone on board, back in the early 1990's due to a fault in the design of the rudder actuator?If this true then it is the end of Boeing.
Not practical. Even on small aircraft the pilot can't override everything. If you have a plane with a constant-speed prop you can only dial in the desired RPM and the system automatically adjusts the propeller pitch to maintain it. The pilot has no direct control over the propeller pitch.These^^ There should be no automated system that the pilots can not override with simple control inputs. Then make sure the people flying the planes are actually *pilots* and not just automated system operators.
That was a simple fix, A rudder actuator as I recall. If this indeed is an airframe design issue the fix is going to be way more complicated. That is unless pilots and passengers are willing to live with the fact it is going to take software to keep the plane in the air (assuming there is an actual software fix for this).Then why wasn't it the end of Boeing when there were multiple incidents (seven, I believe), including two crashes that killed everyone on board, back in the early 1990's due to a fault in the design of the rudder actuator?
Not practical. Even on small aircraft the pilot can't override everything. If you have a plane with a constant-speed prop you can only dial in the desired RPM and the system automatically adjusts the propeller pitch to maintain it. The pilot has no direct control over the propeller pitch.
Pilots and passengers live with it every day, what we can't tolerate is buggy software. Life critical software keeps all modern aircraft flying....
That is unless pilots and passengers are willing to live with the fact it is going to take software to keep the plane in the air (assuming there is an actual software fix for this).
Air Carriers vs BoeingWho is they?
Boeing doesn't pay to retrain pilots. The Air Carriers that buy Boeing planes do. Boeing designed the flight software to make it feel like the older 737 models because customers wanted it that way. Airbus does EXACTLY the same thing with airframes and software. I'm all for Boeing being held responsible for what they did but lets be fact based in the responsibility.
https://airfactsjournal.com/2019/03/can-boeing-trust-pilots/
by Jake Hertz
by Jake Hertz
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