737 MAX 8 Ethiopian si schianta subito dopo il decollo da Addis Abeba


Ciao Luke, un paio di domande/precisazioni

Lukem3d ha detto:
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Il problema del Max 8 Non è di software ma di stabilità aereodinamica.

Boeing pensava di risolvere questo problema con una "coperta" software mutuata dalle aereocisterne militari che produce (boeing KC-767 aerei intrinsecamente instabili in quanto trasportano un carico liquido che si sposta verso la coda quando il muso va in su...
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Hai qualche riferimento di questo? Perchè mi sembra improbabile che siano stati concepiti dei tanker così! Tutte i serbatoi nei quale il movimento del liquido modifica il CG più di un tot hanno delle paratie interne proprio per evitare questo, quindi non capisco perchè un tanker, progettato per fare proprio quel lavoro, non sia stato previsto un sistema simile


Lukem3d ha detto:
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No, non è normale, di solito gli aerei civili vengono progettati per facilitare i piloti ad evitare lo stallo e non per complicargli la vita ( a puro titolo di esempio, solo uno che ho trovato documentandomi per cercare di rispondere a questa domanda che evidentemente interessava solo a me , il Piaggio p180 - un semplice turboprop da circa 7 milioni di euro - ha un design aereodinamico ottimizzato per far abbassare il muso del velivolo all'approssimarsi dello stallo - le alette sul muso perdono portanza poco prima delle ali principali sulla fusoliera ). ..
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Non conosco in dettaglio il P180, ma essendo un T-Tail deve avere PER FORZA un sistema che butta giù il muso, altrimenti soffrirebbe di Deep Stall
 
Il deep stall è tipico di aerei che abbiano : 1) ala a freccia e 2) coda a T. Il P180 non ha ala a freccia, e quindi non soffrirebbe di deep stall, anche senza ala anteriore. Lo scopo di quest’ultima è quello di alleggerire la necessità di deportanza dello stabilizzatore e , come effetto secondario, è stato progettato per stallare 2 gradi prima dell’ala principale, favorendo un momento picchiante.
Per il MAX, l’aumento del gradiente di sforzo fornito dall’MCAS, ha appunto quello di creare artificialmente un momento picchiante , e rendere più difficile l’involontaria entrata in stallo.
 
aerei intrinsecamente instabili in quanto trasportano un carico liquido che si sposta verso la coda quando il muso va in su...

In tutti gli aerei del mondo , quando l’aereo si inclina il carburante defluisce verso la coda. Per fortuna, però, i serbatoi sono più di uno , e posti quanto più possibile vicino al baricentro dell’aereo (a meno che non vengano messi nello stabilizzatore , con una specifica funzione di ottimizzazione del baricentro). Lo spostamento del baricentro generale dell’aereo quando esso si inclina di 15° (sia a cabrare che a picchiare) sono minimi, e comunque abbondantemente all’interno dell’inviluppo di peso e centraggio.
Del resto, se veramente ci fosse un problema di stabilità a causa dello spostamento del carburante quando l’aereo cabra, mi aspetterei nel contempo una diminuzione di controllabilità quando l’aereo picchia,
Purtroppo vedo che in molti siti si confonde la stabilità (statica e a comandi fissi) con la stabilità statica a comandi liberi e quest’ultima, a differenza del nome, non ha nulla a che fare con il rilascio del comando, bensì con gli sforzi di barra. Ovvero, un aereo staticamente stabile a comandi fissi (spostamenti del comando) può essere staticamente neutro a comandi liberi (ovvero quasi nessuna variazione di sforzo per variare la velocità, caratteristica tipica di molti aerei acrobatici).
Le norme militari MIL hanno pure esse un limite inferiore minimo di gradiente di sforzo, che è differente da quello FAR 25, e la configurazione particolare del KC 767 potrebbe richiedere, per le norme tecniche militari, di introdurre un sistema simile all’MCAS per ripristinare il gradiente corretto di sforzo agli alti angoli di incidenza
 
Ovviamente il KC 767 ha le paratie nei serbatoi che attenuano ma non eliminano del tutto il fatto di essere completamente carichi di liquidi.

Non capisco cosa c'entrino i serbatoi completamente carichi di liquido , ci sono su tutti gli aerei, paratie o non paratie. Ovviamente l'articolo di analisidifesa non fà riferimento
a serbatoi/paratie/liquidi, perchè non c'entrano nulla. Come ho scritto più sopra, anche i serbatoi aggiuntivi sono posti in prossimità del baricentro,
ed una inclinazione di 15° in senso longitudinale non varia apprezzabilmente il CG fintanto da farlo uscire dall'inviluppo. Sicuramente la diminuzione di gradiente di sforzi
è da ricercarsi quindi in una particolare configurazione aerodinamica.
 
https://boeing.mediaroom.com/news-releases-statements?item=130434&fbclid=IwAR2VBGDTiLXqdSOCaZMF2OwOMB5aGpnEt8BCOD7NxfK6v5xbzLqUdEulpSs

Boeing Statement on 737 MAX Certification and Return to Service

CHICAGO, May 16, 2019 – Boeing has completed development of the updated software for the 737 MAX, along with associated simulator testing and the company’s engineering test flight. To date, Boeing has flown the 737 MAX with updated MCAS software for more than 360 hours on 207 flights.

Boeing is now providing additional information to address Federal Aviation Administration (FAA) requests that include detail on how pilots interact with the airplane controls and displays in different flight scenarios. Once the requests are addressed, Boeing will work with the FAA to schedule its certification test flight and submit final certification documentation.

“With safety as our clear priority, we have completed all of the engineering test flights for the software update and are preparing for the final certification flight,” said Boeing Chairman, President and Chief Executive Officer Dennis Muilenburg. “We’re committed to providing the FAA and global regulators all the information they need, and to getting it right. We’re making clear and steady progress and are confident that the 737 MAX with updated MCAS software will be one of the safest airplanes ever to fly. The accidents have only intensified our commitment to our values, including safety, quality and integrity, because we know lives depend on what we do.”

In addition, Boeing has developed enhanced training and education materials that are now being reviewed with the FAA, global regulators, and airline customers to support return-to-service and longer-term operations. This includes a series of regional customer conferences being conducted around the world.
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Boeing admits flaws in 737 MAX simulator software after crashes
Aerospace company says it has made corrections to simulator software used to train pilots flying its 737 MAX jets.
Boeing has acknowledged it had to correct flaws in its 737 MAX flight simulator software used to train pilots, after two deadly crashes involving the aircraft that killed 346 people within six months.
The US-based aerospace company said its simulators were incapable of replicating certain flight conditions that contributed to the Ethiopian Airlines crash in March, or the Lion Air accident off Indonesia last October.
"Boeing has made corrections to the 737 MAX simulator software and has provided additional information to device operators to ensure that the simulator experience is representative across different flight conditions," Boeing said in a statement on Saturday. The company did not indicate when it first became aware of the problem, and whether it informed regulators. Its statement marked the first time Boeing admitted there was a design flaw in software linked to the 737 MAX, whose MCAS anti-stall software has been blamed in large part for the Ethiopian Airlines tragedy.
The 737 MAX was grounded around the world in March following the Ethiopian Airlines crash that killed all 157 on board just five months after a similar crash of a Lion Air flight of a 737 MAX killed 189 people. The company said the latest "changes will improve the simulation of force loads on the manual trim wheel," a rarely used manual wheel to control the plane's angle. "Boeing is working closely with the device manufacturers and regulators on these changes and improvements, and to ensure that customer training is not disrupted," it added. Southwest Airlines, a major 737 MAX customer with 34 of the aircraft in its fleet, told AFP news agency it expected to receive the first simulator "late this year".
American Airlines, which has 24 of the aircraft, said it had ordered a 737 MAX simulator that will be delivered and put into operation in December. "As a result of the continuing investigation into both aircraft accidents, we are looking at the potential for additional training opportunities in coordination with the FAA (Federal Aviation Administration) and Allied Pilots Association," it added. On Thursday, Boeing said it had completed a software update for its 737 MAX jets and that is also submitting a plan on pilot training to the US Federal Aviation Administration.
The planes are awaiting approval from US and international regulators before they can return to service. Currently, there is only one flight simulator specific to the 737 MAX in the United States, and it is owned by Boeing, according to FAA documentation. US airlines train their pilots flying the MAX on a simulator built for the 737 NG, the version preceding the 737 MAX in the 737 aircraft family. Oliver McGee, a former US deputy assistant secretary for transportation, said it's vital for pilots to have access to accurate training systems. "These simulators are very important to the airline operators," he told Al Jazeera from Lubbock, Texas. "It can cost about tens of millions of dollars over the life of the aircraft." "American Airlines is already on board, saying we're going to get those simulators and get more data and information, to the manufacturers, from the pilots where the manoeuvrability and controllability of the MCAS takes place," he added. US airlines have targeted August as the date they expect to resume flying on the 737 MAX.

https://www.aljazeera.com/news/2019/05/boeing-admits-flaws-737-max-simulator-software-crashes-190519054206962.html
 
Ieri c'è stato un vertice tra FAA e Boeing che non ha portato a nessun accordo sulle misure proposte dal costruttore per ricertificare i MAX.
Si prospettano tempi più lunghi del previsto.
 
Boeing has admitted it "fell short" when it failed to implement a safety alert system on the 737 Max.

The aircraft was grounded globally in March after two crashes within months.
Boeing boss Dennis Muilenburg said a mistake had been made in the software for a cockpit warning light called an "angle-of-attack (AOA) disagree alert".
He said: "We clearly fell short and the implementation of this angle-of-attack disagree alert was a mistake, right, we did not implement it properly."
In an interview with Norah O'Donnell of CBS News he said Boeing was now fixing the problem.
The alert could have notified pilots and maintenance crews that there was a problem early in the flight.
One flight safety expert said if there had been an AOA disagree alert on board the Ethiopian airlines flight it "would have been the very first clue" for the pilots that something was wrong.
Chris Brady, a pilot and author of The Boeing 737 Technical Guide said: "I'm fairly confident that the Ethiopian Airlines flight probably would not have crashed if they had had the AOA disagree alert" on the aircraft.

Ethiopian Airlines flight ET 302 crashed after an erroneous reading from one of the AOA sensors triggered a flight control system (MCAS) which repeatedly pushed the nose of the aircraft down.
All 157 people on board were killed.
Mr Brady believes that if there had been an alert warning light showing that the AOA sensors were giving different readings, then the pilots might have followed an emergency procedure at an earlier point in the doomed flight.
The procedure, detailed by Boeing in a bulletin to airlines and pilots in November subsequent to the Lion Air crash off Indonesia, involves flipping two switches, and turns-off an automatic control system for the plane's stabilisers.
Boeing said in a statement a month ago that the "alert has not been considered a safety feature on airplanes and is not necessary for the safe operation of the airplane".

This is perhaps the clearest admission so far from Boeing that at least one aspect of the aircraft's build wasn't done properly.
We can't say for certain that an angle of attack disagree alert, which was missing, would have made a big difference.
However, it could have provided the pilots with a useful clue, possibly within seconds of take-off, that something was not right.
Ask any pilot if they would have wanted the alert in their cockpit and you'll get a resounding "yes".
The alert is about flagging that the readings from the plane's two angle of attack sensors don't match.
And the fact that an erroneous reading from one of those sensors kick-started a flight control system, which pushed the plane's nose repeatedly down before it crashed, means the missing alert will surely be of interest to investigators and lawyers representing relatives of those who were killed.

Mr Muilenburg also admitted in the CBS interview that the company knew that the alert system was not active on all 737 Max jets in 2017 and yet did not tell the Federal Aviation Administration (FAA) for 13 months.
He said: "Our communication on that was not what it should have been."
And he issued another apology, saying "it feels personal".
He said that the crashes have had "the biggest impact on me" of anything in his 34 years at the planemaker.

Return to service

The head of the airline industry's trade body, IATA has said the 737 Max is unlikely to re-enter service before August.
Director General Alexandre de Juniac said "we do not expect something before 10 or 12 weeks", although he added a final decision was up to regulators.
Mr de Juniac told reporters in Seoul on Wednesday that IATA was organising a summit with airlines, regulators and Boeing in five-to-seven weeks to discuss what is needed for the 737 Max to return to service, he said.

He hoped that regulators could "align their timeframe" on when the aircraft would be back in the skies.
US operators United Airlines, Southwest Airlines, and American Airlines have removed the 737 Max from their flight schedules until early to mid-August.
Earlier in the day, Mr Muilenburg had told shareholders Boeing aimed to ramp-up its long-term production rate of the 737 Max to 57 a month after cutting monthly output to 42 planes in response to the groundings.
https://www.bbc.co.uk/news/business-48461110

 
Ethiopian will be 'last' airline to resume Max flights: chief

Ethiopian Airlines will be the last airline globally to resume flights with the Boeing 737 Max once it has been certified to return to the skies.
Speaking at the IATA annual general meeting in Seoul today, Ethiopian chief executive Tewolde Gebremariam told reporters that the African carrier will only restart flights with the type "after the regulators decide and when we see airlines start flying it", adding: "We will be the last one".
Three months after the 10 March accident involving flight ET302, Gebremariam says it is too early to make a judgement on the Federal Aviation Administration's (FAA) investigation into the cause of the crash as it is "still a work in progress".
"Lets see how they [the FAA] are going to handle it. Lets see the complete solution and also the certification, lets also see if they can convince the other regulators - then we can only make an opinion," he says.
Gebremariam says that Ethiopian Airlines has been a "long-time, Boeing-only customer" in the past, and while he would like to "maintain" that relationship, the "very tragic" Max crash will have "its own impact" on it.
He agreed that he was frustrated by the comments made by the FAA about the airline's pilots who were flying the aircraft, adding that the airline had made its position "clear" through press releases and public statements.
Gebremariam says at present the Addis Ababa-based carrier has no plans to alter its pilot training programme. He also asserts that the pilots who died in the crash will be ultimately be exonerated in the investigations.
Commenting on reports that one of its pilots has allegedly repeatedly warned senior management that its crew needed more training and better communication to crew members on the aircraft following the Lion Air crash in October 2018, Gebramariam says: "Its a very long story, that pilot had a problem for more than a year with us, so we had to terminate his contract."
He says the Star Alliance airline has "not yet decided" when it will take delivery of the remaining Max jets it has on order. Cirium's Fleets Analyzer shows the carrier has four Max 8s in storage and another 25 on order.
He also says the airline has not calculated the financial impact that the grounding of the type has had on its operations. FG
 
è un problema alle leading edge slat tracks che può essere estremamente pericoloso soprattutto in fase di retrazione (vd. China Airlines flight 120)

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La compagnia AZAL Azerbaijan annulla il proprio ordine di 10 B737 Max per il valore di 1 miliardo di $.
 
Alla fine si torna al Via come a Monopoli:Boeing ha preso il rischio di ricicciare sul 737 e su una cellula vecchia di 60 anni e gli ha detto male. Quelli che han fatto il risk assessment staranno a cancellare la referenza dai CV!

Ora che accade se non lo fanno veramente volare prima di fine anno? Convertono gli ordini in 738 e chiudono il Max definitivamente?


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i-ffss ha detto:
Alla fine si torna al Via come a Monopoli:Boeing ha preso il rischio di ricicciare sul 737 e su una cellula vecchia di 60 anni e gli ha detto male. Quelli che han fatto il risk assessment staranno a cancellare la referenza dai CV!

Ora che accade se non lo fanno veramente volare prima di fine anno? Convertono gli ordini in 738 e chiudono il Max definitivamente?


Inviato dal mio iPhone utilizzando Tapatalk
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Temo che :
chi ha fatto il risk assesment abbia comunque avuto due anni per ricevere complimenti, pacche sulle spalle e bonus monetari
chi ha accettato il risk assement ora cerchi disperatamente di preservare la poltrona o negoziare un'uscita silenziosa e ben remunerata (perchè appunto silenziosa).

Fantaipotesi ancor di più visto il clima
rimpiazzare il Max (col danno d'immagine che ha ricevuto, promuoverlo non è semplicissimo, ossia SCONTI alle stelle, bye bye profitti, bye bye bonus) con qualcosa di più recente.
a) foglio bianco e via....ed arrivederci a tra sei anni circa
b) entrare (come puri assemblatori e magari mettendoci in aggiunta poco più che il marchio) nel progetto MC21 che dovrebbe essere già avanti ammesso che non ci siano blocchi politici e nel frattempo partire dal foglio bianco
c) vedere se nei cassetti dell'Embaer ci sia qualcosa di sfruttabile velocemente (anche qui un quattro anni minimi)

Fosse successo quasi subito dopo il lancio, una chiusura e sostituzione con qualcosa d'altro sarebbe stato più logico.
Adesso ci sono troppi vettori con troppi MAX già ricevuti. Che cosa se ne fanno ?
Se dice "problemi vostri, li avete già pagati", non venderà più neppure una matita
Se invece li "rimborsa" rischia la bancarotta.
Se prova a mettere una pezza e non si trova altro (inerente o meno ma questo è collegato colla tempistica di rientro) magari....

Magari bella JV con Embaer solo per i NB e poi un bel "nuota od affoga" mentre continua coi ben migliori WB.
 
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