Precipitato un B737 Max 8 di ET, conseguenze sul mezzo e sul mercato

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belumosi
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda belumosi » sab 04 mag 2019, 12:26:23

mxp98 ha scritto:Nessuno spam, anzi grazie per gli aggiornamenti e tutti i retroscena.

Quoto e grazie anche da parte mia.
malpensante ha scritto:Non ricordo di aver mai letto niente di più ipocrita in vita mia. Persino Cesare Battisti, che peraltro ha sulla coscienza solo qualche morto e non centinaia, ultimamente mi sembra più serio.
E' una linea obbligata, adesso non possono fare altro che minimizzare e nel contempo risolvere i problemi.
E pensare che sarebbero stati sufficienti provvedimenti limitati e non particolarmente costosi per evitare tutto questo casino e salvare la vita di 346 disgraziati.

kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » sab 04 mag 2019, 13:40:00

Questo articolo spiega bene come il sistema Airbus differisca sostanzialmente

The consequences of spurious sensor readings have affected Airbus as well as Boeing - and unexpected incidents illustrate the difficulties designers and regulators face in predicting and avoiding unintended aircraft behaviour.

Grounding of the Boeing 737 Max followed two fatal accidents involving unreliable angle-of-attack information and persistent automatic nose-down response from a new pitch-control system.

Airbus types have experienced serious issues that appear superficially similar to those affecting the Max. However, some crucial considerations, centred on the Airbus design and time in service, have resulted in far less disruptive regulatory intervention.

Shortly after an Eva Air A330's departure in 2012 it suffered an angle-of-attack sensor jam, at 5°, as it climbed through 11,000ft. Although the angle was shallow, angle-of-attack margins become narrower, increasing the risk of stall, as an aircraft climbs and its Mach number increases.

When the A330 reached an altitude at which this false angle-of-attack data exceeded a critical threshold, the aircraft's stall-protection mechanism responded by automatically commanding nose down.

Investigation of the incident revealed that not only could the flight-control laws command a nose-down pitch, but pilots might not be able to counter the attitude - even if they pulled fully back on the sidestick.

The incident spurred an emergency change of procedures, instructing crews to turn off air data reference instruments if symptoms of a sensor jam emerged, or if the aircraft entered an "unmanageable pitch-down attitude" despite full-aft sidestick inputs.

Analysis of the A330 incident pointed to the possibility that conic plates on which the angle-of-attack sensors were mounted had contributed to icing and a subsequent blockage.

Jamming of two or three sensors at the same angle could cause the stall-protection system to activate, investigators stated.

Operators were instructed, in early 2013, to replace the conic plates with a flat-plate mounting for the sensors.

But a similar incident, in November 2014, involving a Lufthansa A321 climbing out of Bilbao underscored the difficulties in anticipating misbehaviour.

Two of the A321's angle-of-attack sensors froze at a position of 4.5° as the jet passed 19,500ft. It continued to climb but, as it reached 31,000ft, the crew observed airspeed discrepancies and switched off the autopilot, bringing the aircraft under manual control.

The A321 abruptly pitched 3.5° nose-down because, at the speed of Mach 0.675, the jammed sensors were incorrectly showing an angle of attack greater than the 4.2° threshold for the stall-protection system.

With two of the three angle-of-attack sensors jammed at a consistent, albeit wrong, position the A321's air data reference system eliminated the apparently spurious readings from the third sensor. As a result the elevator aileron computer - which controls pitch through the elevators and horizontal stabiliser - took into account only the two incorrect sensors.

"Before these events occurred, the models had accumulated a significant number of flight hours without any such issue" EASA

The aircraft entered a 4,000ft/min descent and the captain was only able to restore and maintain level flight by pulling fully back on the sidestick. Manual nose-up trim was unavailable. Control was eventually regained through measures that led the aircraft to revert to alternate flight law, disengaging the stall-protection system.

Investigators discovered, in the wake of the incident, that the A321 was not fitted with the conic sensor plates suspected in the A330 event, but conventional flat plates. Water ingestion was considered a contributor.

Airbus and the European Union Aviation Safety Agency (EASA) warned A330 and A320-family crews that, if the Mach number continued to increase during a nose-down command, the angle-of-attack threshold for activating stall-protection would continue to decline - resulting in further nose-down orders from the flight-control system.

Pilots were issued with new emergency procedures that instructed them to turn off two of the three air data reference units, forcing the reversion to alternate flight law, if they observed symptoms of jammed angle-of-attack sensors.

There are crucial differences between the events that occurred on the Airbus jets and those preceding the 737 Max accidents, argues EASA.

"While the Airbus events were caused by multiple failures of the angle-of-attack system, the 737 Max issue seems to be caused by just one faulty sensor, thus presenting a higher probability risk," it says.

"The crew of the Airbus aircraft were able to recover control of the aircraft by switching to an alternate flight-control mode and the aircraft landed in a normal way."

EASA points out that, although the 737 has evolved over five decades, the 737 Max is "still a young aircraft model" with relatively little time since service entry in 2017.

"Before these [Airbus] events occurred, the Airbus aircraft models had accumulated a significant number of flight hours without any such issue, allowing certification authorities to perform a comprehensive and robust continued airworthiness review," it adds.

Simultaneous jamming of two angle-of-attack sensors, and the rejection of a valid third, had previously led to the fatal crash of an A320 during a check flight at Perpignan in November 2008.

Water ingested by the sensors, left unprotected during routine washing, froze as the aircraft cruised at 32,000ft. The sensors jammed at low angle-of-attack settings - respectively 4.2° and 3.8° - and maintained these readings as the crew conducted the descent.

As a result the sensors were rendered inoperative and failed to detect the A320's increasing angle-of-attack when, as part of the check flight, the crew deliberately reduced airspeed at low altitude to test the stall-protection system. The aircraft slowed and the horizontal stabiliser trimmed nose-up but the protection system did not activate.

"The crew waited for the triggering of these protections while allowing the speed to fall to that of a stall," the inquiry by French investigation authority BEA found.

When the aircraft stalled, the crew increased thrust, and the stabiliser's nose-up position caused the A320 to pitch up. The crew failed to recover from the stall, which occurred at about 3,000ft; the jet lost height and crashed into the Mediterranean Sea.

EASA describes the high-incidence protection system on the A320 and A330 families as "robust", noting the inclusion of three angle-of-attack sensors compared with two on the 737 Max, normally enabling voting logic to eliminate a single erroneous reading. It adds that the Airbus has "enhanced" monitoring and surveillance of the sensors.

"Safety risk assessments are performed using a methodical approach that accounts for the severity of the potential consequence, the available mitigations - such as crew procedures - and the probability of the root cause to [occur or recur]."

All these considerations, it says, resulted in the differences in regulatory reaction and mandatory actions in the Airbus and Boeing cases.

Seven weeks before the Perpignan crash an upset involving an A330 in cruise exposed the virtual impossibility of certification testing every possible scenario involving flight-control response to corrupted air data.

A Qantas aircraft, operating at 37,000ft, experienced a sudden failure mode in one of the three air data inertial reference units, which started transmitting invalid and frequent spikes in angle-of-attack information.

While the data was invalid the system did not flag it as such. The aircraft's flight-control primary computer abruptly pitched the aircraft 8.4° nose-down, throwing almost all the unrestrained occupants to the ceiling. Over a third of the 315 people on board sustained injuries.

The precise mechanism for the data spikes could not be determined, and the Australian Transport Safety Bureau attributed the event to a "single, rare type of trigger" combined with a "marginal susceptibility" within the air data unit's central processor. Just three occurrences of similar data-spiking had occurred in 128 million hours of operation with the Northrop Grumman units, two of which involved the one fitted in the Qantas aircraft.

Analysis determined that the occurrence was the only known instance in which the design limitation had led to a pitch-down command in over 28 million flight hours on A330s and A340s - a rate that complied with the criteria for events classified as "hazardous" but not "catastrophic".

Investigators pointed out that the flight computer's algorithms were "generally very effective" and could handle "almost all possible situations" involving incorrect angle-of-attack data, adding that the design limitation was "very unlikely" to have led to a more adverse outcome.

Development of the A330 flight-control system involved "many elements to minimise the risk of a design error", including peer review, a system safety assessment, testing and simulation, none of which identified the limitation in the algorithm.

"Due to the wide range of potential inputs into a complex system… simulation and testing programs cannot exhaustively examine all the possible patterns of inputs," says the inquiry, stating that the testing activities for the flight-control computer "would not realistically" have included the multiple data-spike scenario.

Airbus nevertheless redesigned the angle-of-attack algorithm to prevent a recurrence of the Qantas incident, and improved the flight-control computer to enhance its ability to detect multiple angle-of-attack sensor blockages.

The A330 and A321 blockage incidents led EASA to order removal of specific angle-of-attack sensors and their replacement with equipment that was less susceptible to adverse environmental conditions.

Airbus also developed upgrades to the elevator and aileron computers, introducing improved sensor monitoring for the A320 family and later incorporating "flight-control aspects" for the A320neo family, says EASA.

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malpensante
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » sab 04 mag 2019, 14:08:17

Molto interessante.
And Malpensa is going to be our Hub

I-GABE
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda I-GABE » sab 04 mag 2019, 14:50:37

malpensante ha scritto:Non ricordo di aver mai letto niente di più ipocrita in vita mia. Persino Cesare Battisti, che peraltro ha sulla coscienza solo qualche morto e non centinaia, ultimamente mi sembra più serio.


Dovrebbe andare a ripetizione dai colleghi delle case farmaceutiche US - a partire da JnJ - sul come gestire situazioni di questo tipo.
Per quanto in ultima istanza sarà qualche altra testa a cadere come capro espiatorio, la difesa a oltranza in questo modo è assolutamente suicida.


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kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » lun 13 mag 2019, 08:00:59

Situazione legale:

https://www.bloomberg.com/amp/news/arti ... ssion=true

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malpensante
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » lun 13 mag 2019, 10:19:37

E Muilenburg è ancora alla cloche.
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Tulkas
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda Tulkas » lun 13 mag 2019, 22:46:08

Return of Boeing’s 737 MAX Delayed, Posing Further Headaches for Airlines
Planes may not be restored to airline schedules before mid-August or even later, missing most of the summer travel season

https://www.wsj.com/articles/timeline-f ... 1557758701

kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » gio 16 mag 2019, 21:04:16

https://www.seattletimes.com/business/b ... ssion=true

Alcuni commenti mi lasciano un po' così... Non sono sicuro che tutti i piloti usa ce l'avrebbero fatta senza problemi...

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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda easyMXP » gio 16 mag 2019, 21:20:18

Gli americani ce l'hanno sempre più duro di tutti.
Però gli altri aerei in mano agli stessi scarsi (secondo loro) piloti del resto del mondo non danno particolari problemi, il Max se non lo pilota un top gun cade ogni 6 mesi a causa di un design approssimativo e una safety analysis fatta male, e probabilmente intenzionalmente male.

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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » gio 16 mag 2019, 21:56:30

La soluzione è allora consentire il MAX alle linee aeree yankee e vietarlo alle altre.
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda I-Alex » ven 17 mag 2019, 07:26:45

La risposta dei piloti Usa

In a statement Thursday, APA President Captain Daniel Carey cited the November meeting and said, “It’s six months later and who knows how long it will take to implement the new fix, and if it’s even sufficient.”
“Dennis Muilenberg and his engineers need to take full responsibility for the 346 deaths,” Carey added. “Boeing needs to stop dodging responsibility and stop blaming dead pilots for its mistakes.”


https://www.seattletimes.com/business/b ... a-approval
Malpensa airport user

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malpensante
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Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » ven 17 mag 2019, 11:48:29

Non gliel’hanno mandato a dire.
Io non vedo una soluzione veloce.
And Malpensa is going to be our Hub

kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » sab 18 mag 2019, 10:16:20

Da copia di flight international in mio possesso

Development of the updated flight-control software for the 737 Max is finished and Boeing is now working with the US Federal Aviation Administration (FAA) to schedule certification test flights.

The airframer has also wrapped up simulator testing and engineering test flights for the Max. To date, Boeing has accumulated more than 360h across 207 flights on the updated Maneuvering Characteristics Augmentation System (MCAS) software.

"We are now providing additional information to address [FAA] requests that include additional detail on how pilots interact with the airplane controls and displays in different flight scenarios," says Boeing.

The 737 Max was grounded globally following the 10 March crash of an Ethiopian Airlines example, in an accident linked to erroneous activation of MCAS.

The announcement of progress on the software update came a day after the FAA's acting administrator, Dan Elwell, was grilled by US lawmakers examining the certification of the 737 Max and regulatory oversight of Boeing.

Elwell sat before a House Transportation Committee panel for hours, during which he expressed confidence in the FAA's certification work.

But he concedes pilots should have been better informed about the system: "When I first heard of this, I thought that the MCAS should have been more adequately explained… in the manual," Elwell says.

Elwell agrees that the MCAS was "safety critical", but defends the fact that it could be activated by inputs from just a single angle-of-attack sensor, noting that pilots should easily be able to counter the system.

The FAA has reviewed an initial version of Boeing's software fix for the Max, but has not received the final iteration.

"We are expecting the application of the formal MCAS software update soon," Elwell says. "The 737 Max will return to service only when the FAA's analysis indicates that it is safe to do so."

The hearing also served as a forum for lawmakers to opine on both sides of the debate swirling around the 737 Max: whether pilot error or aircraft design was the primary factor in the two fatal crashes of the type.

Overspeed was the "fundamental error", says Republican congressman Sam Graves, referring to the crew of the ill-fated Ethiopian flight, claiming that such a crash could not happen in the USA due to higher standards of pilot training.

However, Robert Sumwalt, chair of US accident investigation body the National Transportation Safety Board, says aircraft must be designed to be safe in the hands of pilots from different regions of the world, with differing levels of training.

"If an aircraft manufacturer is going to sell aircraft all across the globe, it's important that pilots… in all parts of the globe need to know how to operate them," he says.



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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda I-GABE » sab 18 mag 2019, 10:40:25

Non avevo letto la dichiarazione di Graves (nomina sunt omina?), ma è surreale.
Come già detto da altri, ci volino loro sui max!


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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » sab 18 mag 2019, 11:37:54

Come dice Trump, Boeing dovrebbe cambiare nome al MAX. 737 Graves andrebbe benissimo.
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda mattaus313 » sab 18 mag 2019, 15:01:18

Intanto...

Three prominent sales executives are retiring from Boeing Co., leaving key vacancies on the planemaker’s global commercial-marketing team ahead of next month’s Paris Air Show, the aerospace industry’s largest trade expo.

With the turnover, Boeing loses executives with deep customer relationships in some of its most critical markets as the company tries to rebuild confidence in the 737 Max after two fatal crashes. Boeing, which like Airbus is off to a slow start on jetliner sales this year, must also navigate U.S.-China trade tensions.


https://www.bloomberg.com/news/articles ... ium=social
"Because you needed a lot of capital in an airline, you needed to be where the financial markets were, and obviously that's New York"

kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » mer 22 mag 2019, 17:42:53

https://www.flightglobal.com/news/artic ... f213118812

Iniziano ad arrivare le richieste di rimborso...

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kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » sab 25 mag 2019, 11:02:47

Associazione piloti europei dice la sua

Da copia di flight international in mio possesso

European pilot representatives have expressed alarm at the direction of discussions aimed at returning the Boeing 737 Max to service, arguing that crucial aspects of the design philosophy are not being addressed.

The European Cockpit Association (ECA) says it is "deeply disturbing" that the design and regulatory framework which enabled certification of the Max remains the foundation for re-approval without "significant reform".

Global aviation regulators met on 23 May to discuss a software fix and new pilot training that Boeing has developed for the Max. The ECA raises particular concerns over the failure modes that apparently contributed to the fatal accidents involving Lion Air and Ethiopian Airlines aircraft, and the decisions that enabled the Max to maintain a common type rating with previous 737 variants.

"Has the desire for a more marketable common type-rating been prioritised over a safer design of the aircraft?" asks association president Jon Horne. "Are there other systems where the same design logic has been applied?"

Horne says the association will "rely heavily" on the European Union Aviation Safety Agency (EASA) to "scrutinise and explain" the Max's certification and its potential return to service, without simply accepting the word of the US regulator.

"We fully support EASA's prerequisite conditions for allowing the Max to fly again," he adds. "And we understand the pressure that the agency is under."

EASA must "resist" that pressure, he says, and "carry out an independent, thorough review".




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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda mattaus313 » sab 25 mag 2019, 18:39:41

Rapido OT: il primo volo del 777x? Rinviato a causa dei problemi del MAX? Condivide parte del software incriminato?
"Because you needed a lot of capital in an airline, you needed to be where the financial markets were, and obviously that's New York"

kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » sab 25 mag 2019, 19:13:46

mattaus313 ha scritto:Rapido OT: il primo volo del 777x? Rinviato a causa dei problemi del MAX? Condivide parte del software incriminato?
No non condivide nulla, 777x hanno fatto il roll out ma senza I media. Tengono un profilo basso a causa del 737max.

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kco
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Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » mer 29 mag 2019, 08:23:22

Interessante come l'mcas vada a risolvere una maggior tendenza a stallare a bassa velocità e ad alti angoli di attacco del max rispetto all' NG. Se così fosse non bisognerebbe addestrare meglio i piloti in queste condizioni dato che, anche se corretto, l' MCAS potrebbe non funzionare?

Da copia di flight international in mio possesso


The recent pair of fatal crashes involving Boeing 737 Max 8s in Indonesia and Ethiopia has generated considerable debate about crew training for the type, sparked by the interim reports from the two investigating agencies. According to the reports, both crews failed to intervene successfully to save the aircraft following a technical malfunction.

In the spotlight are the training requirements for extending a pilot's existing type rating on one variant in a manufacturer's designated series, such as the 737, to cover an additional variant in the same series - for example, changing from a 737NG to a 737 Max, or among the Airbus narrowbodies, from an A320ceo to an A320neo.

There is a basic question here that the industry needs to review, crew training experts say. Is the designated regulatory minimum training focused on the differences - between systems, performance, procedures and handling - sufficient to make pilots type-rated on one aircraft in a series competent to operate another in the same series? This is a critical issue, because this "differences training" enables pilots to add the new variant - legally - to their licence under the common type rating scheme.

The Max is a hybrid mechanical/fly-by-wire aircraft, no longer the airborne Jeep it was in its classic versions

Senior industry training experts are worried about one particular side-effect of the fierce competition between manufacturers - the battle to keep the costs of training crew to fly new variants as low as possible. Some believe that, although the letter of the law may be met regarding the "operational suitability data" that enables types in a series to be compared for training and operational purposes, the spirit of the regulations may be lost or pushed beyond intended boundaries. An example provided to FlightGlobal by a pilot rated on all the 737 variants is that "the switches [in the different 737 variants] are labelled the same but don't deliver an identical result".

There are other examples of "fudges" by manufacturers to make differences appear less significant than they are, and circumstantial evidence is gathering to the effect that the Maneuvering Characteristics Augmentation System (MCAS) - a system unique to the 737 Max - was one of those. Boeing admits that MCAS was designed to make the Max feel and handle like the NG and earlier models when it is being flown manually at low speed with flaps retracted. Flight International's test pilot Michael Gerzanics confirms the Max does indeed, in normal operation, feel like the NG to fly - although he is critical of the manufacturer's opacity regarding MCAS.

If Boeing's intention was to add a system to make the handling feel the same on the Max as it did on the NG, why did it not brief Max trainee pilots fully on MCAS during the "differences training" courses for pilots in the airlines that took delivery of the first 737 Max aircraft? And why did it not include MCAS details in the flightcrew operating manual (FCOM)? Following the crashes, Boeing has admitted that it should have done both. The crews in the aircraft that crashed were taken by surprise when MCAS intervened unexpectedly, triggered by incorrect sensor inputs. In both cases MCAS had operated at a point when it was not designed to do so.

There is a significant factor here that has added considerably to the competitive pressure Boeing faces. When Airbus went totally fly-by-wire (FBW) on all its new aircraft types with the introduction to service of the A320 series in 1988, it gained an advantage over Boeing in maximising the potential for pilot cross-fleet qualification (CFQ) between all types in its entire fleet. This goes beyond just the common type rating across variants within a series. Boeing now has two FBW aircraft in its fleet - the 777 and 787 - so it is reducing this CFQ disadvantage.

The latest 737's flight control surfaces, however, are still basically mechanically-controlled, with FBW systems like MCAS added to modify handling of the Max. But the Max also features another little-heralded FBW component called the spoiler control electronic (SCE) unit, which interacts automatically with the air data computer, flight control computer and spoiler lever. So the Max is a hybrid mechanical/FBW aircraft, no longer the simple airborne Jeep it was in its classic versions - yet its many devotees still talk about it as if it were.

Despite the considerable differences wrought by re-engining the Max and installing compensating FBW systems like MCAS and SCE, until the 737 Max series was grounded globally on 13 March, the designated "differences training" that pilots had to undertake to extend their 737NG rating to the 737 Max consisted of a few hours of computer-based training on a tablet computer, with no time required in any kind offlight simulator training device.

AIRWORTHINESS DIRECTIVE

The Lion Air 737-8 crash occurred on 29 October 2018. Eleven days later the US Federal Aviation Administration (FAA) issued an emergency airworthiness directive (EAD) related to information emerging from the crash investigation. It stated that, "if an erroneously high angle of attack sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabiliser". This, without naming it specifically, referred to the action of MCAS. The system was not referred to by name in the flightcrew operating manual, nor by describing its intended function as an automatic system.

The FAA EAD then stated its requirement for action by Boeing and 737 Max operators. This entailed "revising certificate limitations of the airplane flight manual to provide the crew with runaway horizontal stabiliser trim procedure to follow under certain conditions". The FAA was advising crews, in the event of an erroneous triggering of the MCAS, to carry out the runaway horizontal stabiliser trim procedure. For crews, perhaps an "MCAS malfunction" page might have been a more intuitive place to look for in the emergency checklist.

"Under certain conditions", it transpires, the MCAS can indeed present the crew with symptoms that look momentarily like those of a runaway horizontal stabiliser trim, but in fact the cause is MCAS operation triggered - as designed - by an angle of attack reading above a certain value when the flaps are retracted (clean-wing). If that angle of attack were a true indication, it would be warning the MCAS that the aircraft is closing with the "clean-wing" stalling speed. In this small section of the flight envelope, when the aircraft is being manually flown and the angle of attack is registering above the trigger level, the MCAS is programmed to motor the horizontal stabiliser to push the nose down, reducing the angle of attack.

The detailed reporting of this issue that has appeared in media since the two crashes has tended to focus on questioning why Boeing avoided providing details of MCAS to pilots, rather than on the reasons why a system like MCAS was needed at all, and whether or not its design and potential failure modes were subjected to sufficient scrutiny.

The significant changes in the Max compared with the NG include a higher-power, heavier engine with a bigger fan. The engine's size meant that, to maintain ground clearance beneath the cowling, its pylon had to site the engine further forward and higher relative to the wing leading edge. The nose undercarriage length also had to be increased by 8in, giving the aircraft a higher nose-up attitude on the ground and during landing. All these effects combined to change the wing/engine-cowling aerodynamics and the engine thrust vector.

The MCAS was needed because, without it, the Max would have been vulnerable to stalling when flying under manual control at low speed with flaps up. According to a report filed to the Royal Aeronautical Society (RAeS) Flight Operations Group (FOG), this occurs because, in that small corner of the Max's flight envelope, the aircraft had a tendency to pitch nose-up due to aerodynamic and power vector differences between the NG and the Max.


The unanswerable question - at this stage - is whether the FAA would have felt able to certificate the 737 Max with the knowledge of this increased stalling risk but without automatic pitch compensation from a system like MCAS. And even if it would have approved it without MCAS, the marked differences in handling characteristics between the 737NG and the Max in parts of the flight envelope might have required a "differences training" regime that demanded expensive pilot time in a flight simulator training device - perhaps even a full flight simulator.

The report to the RAeS FOG, by a member fresh from carrying out the Max "differences course", remarks: "The new system has a number of added (and mainly automatic) functions, such as Maneuver Load Alleviation, Emergency Descent (increased spoiler deflection), Elevator Jam Landing assist (uses spoiler deflection to augment pitch requirements) and Landing Attitude Modifier [which] helps pitch control on the glideslope at low flap settings, and is required to maintain clearance for the nose landing gear's 8in extra length." The reporting pilot said there was "no mention" of MCAS on the course.

The conundrum the industry faces right now is that airlines are always happy for manufacturers to produce new, more efficient variants of successful aircraft such as the 737, but they do not want to have to pay for their pilots to take time away from the line to train to extend their type rating to the new machine. For that reason the manufacturers work hard to minimise the changes, sometimes applying cosmetic fixes to mask genuine differences, to stay within the limitations that allow the common type rating for the series to be extended to the new machine.

Some influential people at the top of the training and flight safety world now believe that there needs to be a thorough review of existing common type ratings and cross-crew qualifications. It is understood that the International Civil Aviation Organisation is working on the subject, but if that is indeed so, it is not ready yet to talk about it. It would be a touchy subject for both the airlines and manufacturers, because it might highlight the need for more detailed "differences training" or even rule that a particular variant in a series has too many differences and thus demands a separate type rating.

On the other hand, the pressure to limit differences can be a constraint on offering potential technological advances that are ready for deployment, so a reality check might give manufacturers the opportunity to offer better products.

By the time this article appears the FAA will have presented to a gathering of significant national aviation authorities (NAAs) a "software fix" for MCAS, and proposed modifications for the differences training that take the new changes into account. On 16 May Boeing reported that it had completed not just simulator tests on the new systems, but more than 360h of testing in some 207 flights.

MODIFIED SYSTEMS

The FAA will certificate the modified MCAS and associated systems when it believes the US-based 737 Max fleet can safely fly again. Information released so far indicates that it will involve MCAS getting its sensor feed from both the aircraft's angle of attack vanes, not just one as before, and a cockpit warning of "AoA disagree" if the two sensor vane readings diverge significantly.

The US Air Line Pilots Association stated on 8 May that it is satisfied with the proposed fix, and ventured its opinion that the 737 Max with the newly-modified MCAS will not need simulator time to conduct a differences course. It will be up to the foreign NAAs to determine whether they are sufficiently convinced of the new system's integrity to withdraw their grounding orders, and to approve the proposed parameters for the differences training.

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malpensante
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Località: Milano

Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda malpensante » mer 29 mag 2019, 08:59:31

Storia di straordinaria miopia.
And Malpensa is going to be our Hub

kco
Messaggi: 4472
Iscritto il: sab 05 gen 2008, 09:01:18

Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » dom 02 giu 2019, 17:32:39

Da copia di flight international in mio possesso


A creaking supply chain unable to keep pace with ever-more-demanding output rates meant that even before the grounding of the 737 Max, Boeing's narrowbody line was enduring some form of crisis.

Two tier one suppliers, in the shape of CFM International and Spirit AeroSystems - and for the 737 there are few more crucial to the programme - were struggling to match Renton's relentless production rises.

Late deliveries of fuselages caused assembly snarls, while similar problems with shipments of Leap-1B engines only exacerbated the issue.

A pool of incomplete aircraft had already begun forming around Boeing's single-aisle assembly line near Seattle even before the Max grounding added to their number.

Of course, there are many degrees of crisis, and the safety fears around the re-engined 737 - not to mention the financial hit and reputational stain Boeing has suffered - are clearly an order of magnitude above the airframer's industrial difficulties.

The tribulations experienced following the twin tragedies may have provided an opportunity for Boeing to get its house in order

But the tribulations experienced following the twin tragedies may have provided an opportunity for Boeing to get its house in order.

Chief executive Dennis Muilenburg has indicated that the grounding and consequent decision to reduce 737 output to 42 aircraft per month, from 52 and rising previously, has allowed Boeing to catch its breath.

Muilenburg promises "significant improvements" have been incorporated to its operation, even while CFM and Spirit have maintained higher rates during their recovery.

Indeed, he goes so far as to describe the Max crisis as a "defining moment" for the company, from which a "stronger" business will emerge.

Muilenburg may well be right (and of course, he would say that), but there are many hurdles to clear before Boeing can begin celebrating its industrial achievements.

Once the Max grounding is lifted there will be a battle to regain trust - of customers, pilots and the fare-paying public - and then to clear its parking lot.

Only then can Boeing properly advance the thrust levers on its production line and validate its assumptions.

Strength can be gained through adversity, but it is no means a given. Boeing will be hoping that it has used its enforced breathing room wisely.

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kco
Messaggi: 4472
Iscritto il: sab 05 gen 2008, 09:01:18

Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » dom 23 giu 2019, 12:20:22

La storia dell' MCAS


https://www.seattletimes.com/seattle-ne ... ssion=true

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kco
Messaggi: 4472
Iscritto il: sab 05 gen 2008, 09:01:18

Re: Precipitato un B737 Max 8 di Ethiopian

Messaggio da leggereda kco » mer 26 giu 2019, 23:20:04

https://mobile.reuters.com/article/amp/ ... ssion=true

Pare, ma non è confermato, che siano sorti ulteriori problemi.

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