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… the aircraft design allows for it, but practice shows …
Yo gums, :ok:
“The investigation team agrees that the aircraft design allows for it. But, the air accidents investigation practice shows that it is not always able to promptly identify the out-of-trim stabilizer position, as well as to detect the mere fact of the stabilizer prolonged motion.” This is directly relevant to the 737 Max, subject to the NG and Max having similar trim (aero) characteristics - unlikely given the Max accidents and investigations. 5.21, if applicable to the Max, could be read as - change the aero issues to match the current trim / control system capability. - “reasonable amount of engineering concepts” - 5.21. Consider the practicability to implement the design changes of the stabilizer control system to reduce the risk for the pilot to set stabilizer in-flight into out of trim position. Note 38. In the Comments to the draft Final Report the aircraft manufacturer suggested to remove this recommendation, reasoning that the Boeing Company design philosophy implies the pilot can fully operate with the available deflection of flight controls, including the stabilizer control. This may be required in a variety of non-normal situations, for example at the total loss of hydraulic system/hydraulic circuits’ pressure. At the same time according to the manufacturer, the aircraft design provides for reasonable amount of engineering concepts for the PM to stop the inflight stabilizer setting into the out of trim position by the PF. The investigation team agrees that the aircraft design allows for it. But, the air accidents investigation practice shows that the PM, who monitors the flight management and aircraft control actions by the PF, is not always able to promptly identify the out-of-trim stabilizer position, as well as to detect the mere fact of the stabilizer prolonged motion. The investigation team notes that at the current level of technological development the combination of the mentioned engineering concepts is a possible solution: the limitation of the stabilizer deflection angles, when this could result in the adverse consequences, and the full travel/deflection when actually necessary. |
Originally Posted by gums
(Post 10630392)
Way off topic now, are we?
---------------------------------------------------------- Salute! Well, having done hundreds of rolls and "things you have not dreamed of", to borrow a line from High Flight. You can roll easily without initially getting the nose high if in a small, or nimble plane. Problem with the big boys is inertia, and nose will dig in easily. Hence nose high to start. OTOH.... The ET flight had extreme nose down trim, so every degree of roll from normal erect provides less of a lift vector below the horizon, right? Eventually, all of its lift vector is above the horizon when completely inverted. So a technique I used on most jets to avoid the nose high entry was applying forward stick and a touch of nose down trim as bank angle increased past 90 deg, and maybe some top rudder until over 90 deg of bank. Could literally roll within 20 feet of initial altitude, and the T-birds and Bluers and Arrows and Snowbirds show this every performance. So Denzel's manuever is theoretically possible. And worry about motors quiting later. 737 flies O.K in glider mode due to the mechanical connections, right? We need "wonkazoo" to comment, as he flew aerobatic demos all the time. The Alaska folks should get a post humous medal of honor for even trying the Denzel trick, as they had nothing to loose. And IMHO biggest mistake was not trying to land when things started acting up. Of course if they didn't turn off the electric trim motor, then they could have lost it over L.A. I feel the complete ET flight report will assign some contributing factor to the crew for not slowing down, and likely mention CRM. I feel that they did not know enough about the mechanization of MCAS that kept applying nose down trim when they were not countering it with the button of the wheel, plus the 5 second delay, plus...... Gums opines... Sorry for the late reply- busy week and a hockey tournament for kids so hadn't checked in for awhile. It's a great question to ask, both to illuminate why this was not a possible out for either of the crews, and also realistically how real unusual attitude training and experience (as opposed to the lip service now given) could save lives. First some clarification of definitions. The terms aileron roll and barrel roll have been variously conflated and misdescribed by numerous posters. I'm not going to revisit the descriptions, just describe each accurately here. An aileron roll is a roll performed in level flight, around the center horizontal axis of the airplane. It is an uncoordinated roll, meaning that all three primary controls are used individually to perform the maneuver. You start the roll by applying full left aileron (in western powered aircraft anyway) and as the airplane rolls through 45 towards 90 degrees you feed in right (top) rudder to keep the nose above the horizon. As you pass 90 degrees you start rolling out the rudder and adding nose down stick, again to keep the nose above the horizon. Rudder goes to neutral at the 180 degree point and maximum (necessary) forward stick is reached. As you roll towards 270 degrees forward stick is relaxed while left (top) rudder is added until at 270 degrees the elevator is neutral, left rudder is at it's max, which you begin to remove as you roll back towards positive 1G flight. I should properly note (ironically) that usually you set the trim to aerobatic neutral, which will require significant back pressure in level upright flight and less forward pressure when negative, so some of the timings I listed above would in reality be off a bit. Finally- you will go through a full range of +1 to -1 to +1G through the maneuver. A barrel roll Is a roll begun from level flight and it is a fully coordinated roll. In an appropriately powered airplane you can start from straight and level, but for most you want to enter a shallow dive up to Vmc or so before beginning a smooth slightly more than 1G pullup to bring the nose anywhere from 30 to perhaps 50 degrees above the horizon if you have a really slow roll rate. If you do this properly you have placed the airplane on a ballistic trajectory which will allow you plenty of time to roll through 360 degrees before returning to your start altitude. Once you have a positive rate of climb you begin to roll in coordinated form (Aileron and rudder) until you pass through the inverted position hopefully a little before you reach the top of your climb. (This allows you to control exit altitude safely.) Throughout this rolling sequence the airplane will be changing heading- first to the left, and after rolling inverted back eventually to the original heading. This isn't really a 1G maneuver as you cannot get the airplane nose up, or recover from the nose down finish at 1G, but it is very benign and properly performed need not be more than 1.5-2G. A bunt is a nose down pitching maneuver that ends up as 1/2 or a full loop. Historically a bunt is begun from level flight, by retarding power and when your target airspeed is hit and you have confirmed enough altitude for safety you begin to smoothly feed in nose down stick, increasing the amount of stick as you approach inverted due to the increased airspeed and need to maintain a constant radius. To do this your angular velocity must increase, hence the need to push harder. This is one of the most abstractly terrifying maneuvers anyone can do and it is distinctly uncomfortable as at maxim rate of change/g loading you will be pushing between 5 and 6.5G at a minimum. Hopefully from that you will see that what is being discussed here is a possible combination of two figures- the barrel roll and the bunt. I have to go get kids, so let's call that Part I and I'll try to finish tonight. Cheers!! dce |
@wonkazoo: seriously off thread and should be moved somewhere else. But these definitions are very different from what I have been taught. In fact if I used the terms like this my acro instructor (significant figure in local IAC etc etc) would disown me. Here is what I have been taught (and I believe is the terminology used by IAC):
-- aileron roll: what you have described as a barrel roll. Coordinated, positive G and neutral elevator throughout. Can keep a glass of water on the glareshield if you're Bob Hoover. Must be done fairly quickly (generally at the aircraft's maximum roll rate unless it's an Extra) to keep the nose drop under control. -- slow roll: what you have described as an aileron roll. Totally uncoordinated, nose kept on a point by carefully synchronised use of all three controls. Highly vomit-provoking. Can be done as slowly as you want, the extreme case being a rolling turn. -- barrel roll: combined loop and roll, performed similarly to an aileron roll but with up elevator throughout. Not afaik used in competition, but fun to do around appropriately sized puffy cumulus. -- bunt: very much a British-English term for exactly what you describe. A pushover in US English. I often see the term "barrel roll" used to describe what I would call an "aileron roll". If I inadvertently hold back stick while performing a roll, I get told "you barrelled that". Maybe the UK terminology is different, I've never flown acro (or indeed aeros) in the UK. (Just like I learned to ski in French, it was years before I could talk about skiing in English). |
Originally Posted by gums
(Post 10632007)
Salute!
My conviction is that there is more of an aero problem with the MAX than we are being told. Gums sends... In other words, documentation of the aero problem which MCAS is supposedly minimizing when it's not going full HAL. Surely there should be some reports by the Boeing test pilots. Where are these reports? And by the way where are those test pilots today? The press has made much of the technical pilot's email, but he was writing manuals, not flying the plane before MCAS was shoehorned in. At that level of competence, any community is small. There are people who know and won't talk. I assume come the lawsuits, they will. Edmund |
Originally Posted by n5296s
(Post 10632043)
-- slow roll: what you have described as an aileron roll. Totally uncoordinated, nose kept on a point by carefully synchronised use of all three controls.
Just to say that to maintain altitude in a slow roll, the nose isn't exactly kept on a point, but travels between 'erect' flight attitude, and inverted flight attitude (= a bit higher), describing what Eric Müller called a 'sacred circle' around a point. This is what I've been practicing from my beginnings in aerobatics, and what I taught my students with very good results in competition. Back to the original point : any sturdy and sufficiently fast rolling aircraft can perform an aileron/barrel roll or something in between with a trained pilot at the controls. A boeing 707 was rolled more than once. As Wonkazoo mentioned, the key is having the nose sufficiently high. BTW I seriously doubt that Bud Holland, of Czar52 fame, would have succeeded in rolling a B52 like he dreamed to do one day. Too flimsy wings, and spoilers only in my opinion. FWIW |
Originally Posted by edmundronald
(Post 10632045)
The rest of us non-pilot idiots here really wonder what the native behavior of the MAX without MCAS is like.
In other words, documentation of the aero problem which MCAS is supposedly minimizing when it's not going full HAL. Surely there should be some reports by the Boeing test pilots. Where are these reports? And by the way where are those test pilots today? The press has made much of the technical pilot's email, but he was writing manuals, not flying the plane before MCAS was shoehorned in. At that level of competence, any community is small. There are people who know and won't talk. I assume come the lawsuits, they will. Edmund The technical pilots do not write the manuals or books, as another department does this. All technical pilots do is to ensure that new changes in equipment are compared (with the previous variant, in this case the NG.) and added to the appropriate chapters already in current print. |
RE fly,,,
As Wonkazoo mentioned, the key is having the nose sufficiently high. BTW I seriously doubt that Bud Holland, of Czar52 fame, would have succeeded in rolling a B52 like he dreamed to do one day. Too flimsy wings, and spoilers only in my opinion. FWIW |
Salute!
Hoover did things when he was asleep that none of us could hope to do wide awake, sober and having tried it a hundred times. At a show in Ogden back early 80's his Pony broke, so he borrowed a P-38 and put on a helluva show. He then did his Shrike show where he shuts down the motors, loops the thing, rolls the thing and deadsticks in and stops in front of the crowd. Oh yeah, raises his glass of tea(?) that had been parked on the glareshield. Gums sends... |
Originally Posted by n5296s
(Post 10632043)
@wonkazoo: seriously off thread and should be moved somewhere else. But these definitions are very different from what I have been taught. In fact if I used the terms like this my acro instructor (significant figure in local IAC etc etc) would disown me. Here is what I have been taught (and I believe is the terminology used by IAC):
-- aileron roll: what you have described as a barrel roll. Coordinated, positive G and neutral elevator throughout. Can keep a glass of water on the glareshield if you're Bob Hoover. Must be done fairly quickly (generally at the aircraft's maximum roll rate unless it's an Extra) to keep the nose drop under control. -- slow roll: what you have described as an aileron roll. Totally uncoordinated, nose kept on a point by carefully synchronised use of all three controls. Highly vomit-provoking. Can be done as slowly as you want, the extreme case being a rolling turn. -- barrel roll: combined loop and roll, performed similarly to an aileron roll but with up elevator throughout. Not afaik used in competition, but fun to do around appropriately sized puffy cumulus. -- bunt: very much a British-English term for exactly what you describe. A pushover in US English. I often see the term "barrel roll" used to describe what I would call an "aileron roll". If I inadvertently hold back stick while performing a roll, I get told "you barrelled that". Maybe the UK terminology is different, I've never flown acro (or indeed aeros) in the UK. (Just like I learned to ski in French, it was years before I could talk about skiing in English). You are correct- Barrel Rolls are not a recognized figure in either the FAI or IAC. If you want to parse this to the nth degree it isn't a recognized aerobatic figure in any competition series I am aware of. (Nor did I suggest it was.) As to a loop and a roll or something like that it's just not true. There is a figure that I have seen historically called a barrel roll that ends up with the airplane on a heading 90 degrees from the original heading, but this is not a modern day description, at least here in the US. Your suggestion that readers should look up Bob Hoover Barrel Roll while pouring water is a good one. Aileron rolls are notslow rolls by any definition, in fact in a modern day aerobatic monoplane or biplane the roll rate is in the neighborhood of 400 degrees+ per second. (An aileron roll is a recognized figure in the FAI catalog.) Suggesting that they are slow is bonkers. Yes, two point or four point rolls slow it down a bit in overall time, but the roll rate remains the same. Rolls can be added to a turning circle or a 45 upline or a vertical up or downline or the top or bottom of a loop. The roll rate and control inputs are different in each example. The reason I defined clearly those two rolls is that they represent the entire field of options as described in the query. Equally the reason for defining a bunt is to understand what the actual goal of the sequence is: To create a positive rate of climb, even if inverted that would allow the pilot to recover the airplane. Initially I discounted the possibility entirely, and I still think a realistic outcome involving a deliberate roll to inverted before the plane pushes itself using negative G to a ballistic trajectory is unlikely in the extreme, but I can come up with a few scenarios, and at least one that would work in theory, and I'll try to post them later when I have time to jot them down. Finally, as to this topic being off-topic for the thread: Well we can just wait for Boeing to force feed us their solution and accept it no matter what, or we can as a community ask questions and where merited discuss the thoughts that those questions provoke. I find the question challenging as given my own experience it is an interesting idea to explore- certainly in the two accident aircraft the outcome could not have been any worse. Warm regards, dce |
wonkazoo Most of my reply is in a PM. But just to say here that I totally agree with your last paragraph. My remark about being off-thread applied to my own reply, not to your postings.
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Boeing chief engineer-Hamilton-Retires
Gosh oh gee - imagine that - pulled the cord on golden chute
Boeing chief engineer at center of 737 MAX crisis retires Dec. 4, 2019 at 1:47 pm Updated Dec. 4, 2019 at 2:02 pm By Dominic Gates Seattle Times aerospace reporter Boeing Commercial Airplanes chief engineer John Hamilton, who was appointed in March to lead its response to the deadly 737 MAX crashes and testified before Congress alongside CEO Dennis Muilenburg, is retiring, the company informed employees Wednesday. The news was conveyed in an internal memo from the new head of Boeing Commercial Airplanes, Stan Deal, and Boeing’s chief engineer, Greg Hyslop. “John had planned to retire last year, but we asked him to stay on to help us with the 737 MAX investigations and return to service efforts,” they wrote. “We are immensely grateful to John for lending his expertise and leadership during a very challenging time.” Hamilton took center stage alongside Muilenburg at two contentious Congressional hearings last month. In the second of those, House Transportation and Infrastructure Committee chairman Peter DeFazio, D-Ore., presented internal Boeing documents indicating that, long before the MAX was certified, some Boeing engineers expressed worry internally about the flight control system that went wrong on the two crash flights. Hamilton said he wasn’t aware of some of the documents and said the revelations should be interpreted as evidence of an open culture at Boeing in which engineers could raise questions. Though that five-hour grilling of Hamilton and Muilenburg raised new questions and brought calls for the CEO’s resignation, Boeing since then has stuck to its contention that its software fix for the MAX is almost ready and that the Federal Aviation Administration (FAA) might give it clearance for a return to service by year-end. Many industry observers now think January is more likely for initial FAA approval, and that it will be several months after that before passengers fly on the plane in the U.S. Hamilton’s Boeing career covered multiple airplane programs and roles, including serving as chief project engineer for the 757, the 737 NG (the model prior to the 737 MAX), and the Navy’s 737 variant for hunting submarines, the P-8A. From April 2016 through March, Hamilton was vice president of engineering for Boeing Commercial Airplanes, responsible for all the company’s engineering design and airplane-certification work, including the final certification of the 737 MAX. Hamilton also led Boeing’s Aviation Safety organization. At an air safety conference in Seattle in November 2018, less than two weeks after the first crash, Hamilton shared his own experience of personal dread at news of an airline accident. His wife is an Alaska Airlines flight attendant who on Jan. 31, 2000, was flying out of Puerto Vallarta in Mexico. When Hamilton heard that Flight 261 out of that city and bound for Seattle had crashed, he feared she was among the 88 killed. He found out later she was on a different flight. Hamilton will be replaced by Lynne Hopper, who in March took over his role as vice president of Engineering for Boeing Commercial Airplanes. Boeing said that in addition to leading the Commercial Airplanes engineering team, she will support the efforts to return the MAX to service and work closely with the company’s centralized Safety organization that was created in September, led by Beth Pasztor. Previously, Hopper was the vice president of Boeing Test & Evaluation, where she was responsible for laboratory and flight-test operations in support of certifying Boeing commercial and military jets. From 2004 to 2007, Hopper led the development of delegated authorized representatives, the Boeing employees who work on behalf of the FAA to certify airplanes. The role of these authorized representatives and the entire regulatory system of delegating oversight to Boeing has come under intense scrutiny following the MAX crashes. Hamilton’s departure follows the retirement in July of Eric Lindblad, the Boeing vice president who ran the Renton assembly plant and managed the 737 MAX program. Boeing likewise insisted then that Lindblad, highly regarded as a factory operations expert, had expressed his desire to retire the previous year, before the crashes. |
Originally Posted by Grebe
(Post 10632675)
Gosh oh gee - imagine that - pulled the cord on golden chute
Appreciate you posting that information. Interesting times ahead and one wonders what led to his retirement now, and not last year, as he had planned. |
Originally Posted by 568
(Post 10632709)
Grebe,
Appreciate you posting that information. Interesting times ahead and one wonders what led to his retirement now, and not last year, as he had planned. Designated sacrifice or fallee. Avoids firing and retribution claims- parachute has no tattered panels- but unclear if who will pay for any legal - criminal complaints defense. Its the legal ' sorry about that ' defense- and his retirement is " just part of our long planned re-organization and the standard ' thank your for your service ' award. |
but unclear if who will pay for any legal - criminal complaints defense. I doubt there are many engineers who would be willing to act as DERs/ARs if they could be held personally liable - I certainly wouldn't have. The nightmare scenario of your system causing a fatal crash is bad enough. Knowing that such a nightmare could also result in financial ruin for you and your family - why would anyone be willing to do that? It's not like ARs get any extra pay in return for their responsibilities... |
Originally Posted by tdracer
(Post 10632738)
Boeing is on record as providing legal defense and financial protections to their "Authorized Representatives" (ARs) if they are sued for their actions as an AR (provided they acted in good faith).
I doubt there are many engineers who would be willing to act as DERs/ARs if they could be held personally liable - I certainly wouldn't have. The nightmare scenario of your system causing a fatal crash is bad enough. Knowing that such a nightmare could also result in financial ruin for you and your family - why would anyone be willing to do that? It's not like ARs get any extra pay in return for their responsibilities... |
It might have something to do with United's "totally unrelated to the MAX" decision to go with Airbus for 50 planes. The fact that United even felt it necessary to explain shows how well Boeing's mitigation efforts have been working, and this fellow was one of the more visible but apparently expendable soldiers leading that effort.
A major criminal indictment is unlikely, for purely national political reasons. Neither party is going to want to have "wiping out America's passenger jet industry" on their resume. It is more likely that the government will buy any planes that 'Boeing can't sell, if that happens. Just look at how many bankers were jailed for fraud after the banking bailout for a roadmap to the future. United chooses Airbus |
Originally Posted by Water pilot
(Post 10632774)
It might have something to do with United's "totally unrelated to the MAX" decision to go with Airbus for 50 planes. The fact that United even felt it necessary to explain shows how well Boeing's mitigation efforts have been working, and this fellow was one of the more visible but apparently expendable soldiers leading that effort.
A major criminal indictment is unlikely, for purely national political reasons. Neither party is going to want to have "wiping out America's passenger jet industry" on their resume. It is more likely that the government will buy any planes that 'Boeing can't sell, if that happens. Just look at how many bankers were jailed for fraud after the banking bailout for a roadmap to the future. United chooses Airbus |
Originally Posted by tdracer
(Post 10632738)
Boeing is on record as providing legal defense and financial protections to their "Authorized Representatives" (ARs) if they are sued for their actions as an AR (provided they acted in good faith).
I doubt there are many engineers who would be willing to act as DERs/ARs if they could be held personally liable - I certainly wouldn't have. The nightmare scenario of your system causing a fatal crash is bad enough. Knowing that such a nightmare could also result in financial ruin for you and your family - why would anyone be willing to do that? It's not like ARs get any extra pay in return for their responsibilities... |
Originally Posted by Water pilot
(Post 10632774)
It might have something to do with United's "totally unrelated to the MAX" decision to go with Airbus for 50 planes. The fact that United even felt it necessary to explain shows how well Boeing's mitigation efforts have been working, and this fellow was one of the more visible but apparently expendable soldiers leading that effort.
A major criminal indictment is unlikely, for purely national political reasons. Neither party is going to want to have "wiping out America's passenger jet industry" on their resume. It is more likely that the government will buy any planes that 'Boeing can't sell, if that happens. Just look at how many bankers were jailed for fraud after the banking bailout for a roadmap to the future. United chooses Airbus Between the MAX grounding and the pickle forks, I am hearing rumours that my airline has suddenly woken up to the Boeing "Black Swan" and will go with Airbus for its NG fleet replacement of around 80 narrow bodies just to mitigate the existential risk to its business. |
Originally Posted by OldnGrounded
(Post 10632791)
How many P-8 Poseidon MAXes can the Navy use? How many BBJ MAXes could the State and Defense Departments absorb? "As many as necessary?"
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