Here's an idea.
Boeing potrebbe prendere il 797, cestinare il progetto attuale, creare un nuovo aereo per short-haul che rimpiazzi il 737, farlo diventare l'aereo piu' efficiente di sempre e farci una barcata di ordini!
737 MAX 8 Ethiopian si schianta subito dopo il decollo da Addis Abeba
- Autore Discussione carter72
- Data d'inizio
Here's an idea.
Boeing potrebbe prendere il 797, cestinare il progetto attuale, creare un nuovo aereo per short-haul che rimpiazzi il 737, farlo diventare l'aereo piu' efficiente di sempre e farci una barcata di ordini!
...e nel frattempo, passata la buriana (perché passerà, nonostante tutto), qualcuno comprerà a prezzo di realizzo i MAX8 o MAX9 che pochi altri vorranno!
In linea di massima sono d' accordo con te, ma c' è qualcosa che non mi torna: quella fusoliera è stata usata per 4 modelli e non so quante versioni: lunga per il 707, media e corta per il 727 ed il 737, lunga con nuova prua per il 757;
e poi ancora ciascuno con la sua ala diversa, e la configurazione motori: uno quadrimotore, uno trimotore con motori in coda, uno bimotore coi motori piccoli, uno bimotore coi motori grossi... come mai è solo questo modello a dare problemi? hanno toccato solo il motore senza toccare l' ala come penso abbiano fatto invece per tutti gli altri modelli/versioni?
https://www.flightglobal.com/news/a...he-nma-might-prepare-boeing-for-a-737-455844/
Chiedo perdono per l'OT.
Il dubbio che si sia raggiunto un limite progettuale è venuto anche a me, ma da ignorante in tema, preferisco attendere la fine delle indagini prima di trarre conclusioni. Ma credo sia normale il dubbio: nonostante gli aggiornamenti e la continua evoluzione di ali e della grandissima parte dei componenti, la fusoliera ha 60 di storia ormai (se non sbaglio). Prima o poi, a meno di sconvolgimenti, arriva il momento in cui un progetto non può più essere aggiornato o adattato (si pensi anche alle auto che non si sono potute adattare agli standard di sicurezza europei)
Puo' anche darsi che data la situazione sia meglio prima fare il rimpiazzo del 737 e poi stretcharlo, ma tutto sommato io penso che se sistemano le cose di cui sopra questo aereo potra' funzionare bene in piena sicurezza, a costo di stratificare sistemi di sicurezza. Sensazione di pancia non suffragata da molti approfondimenti.
Quindi se mantengono i piani dovrebbero velocizzare un po' il 797 e poi da questo derivare in qualche modo il successore del 737. Vedremo nei prossimi anni.
E scusate per la recidiva nell'OT
Quindi se mantengono i piani dovrebbero velocizzare un po' il 797 e poi da questo derivare in qualche modo il successore del 737. Vedremo nei prossimi anni.
E scusate per la recidiva nell'OT
Va bene velocizzare o magari ripensare il B797 per coprire anche il B737 ma si parla comumque di anni. Debbono trovare una soluzione per i B737Max. Un dubbio così su due piedi, il B737 NG è una soluzione tampone?
Buongiorno,
per chi avesse tempo e (soprattutto) voglia o per chi soffre di insonnia e cerca un metodo per addormentarsi :very_drunk:, raccomando la letture dei "Corners" di Bjorn Fehrm, analista aeronautico molto esperto anche in temi aerodinamici. Sul sito leehamnews ha una rubrica dedicata alla pitch stability, analizzata in conseguenza al crash della Lion Air e ripresa dopo il crash del volo Ethiopian. Sono articolo molto interessanti che descrivono in maniera sintetica ma esaustiva la dinamica e lo sviluppo della stabilitá attorno all´asse orizzontale per un aeromobile e la interazione dei vari elementi della struttura, dall´ala presa come parte singola indipendente ai motori stessi.
Colgo inoltre l´occasione per farvi i complimenti, ho trovato una marea di informazioni e spunti interessanti in questo thread. Grazie a tutti per questa discussione.
https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopian-airlines-flight-302-crash/
https://leehamnews.com/2018/11/23/bjorns-corner-pitch-stability/
https://leehamnews.com/2018/11/30/bjorns-corner-pitch-stability-part-2/
https://leehamnews.com/2018/12/07/bjorns-corner-pitch-stability-part-3/
https://leehamnews.com/2018/12/14/bjorns-corner-pitch-stability-part-4/
https://leehamnews.com/2019/01/11/bjorns-corner-pitch-stability-part-5/
https://leehamnews.com/2019/01/18/bjorns-corner-pitch-stability-part-5-2/
https://leehamnews.com/2019/01/25/bjorns-corner-pitch-stability-part-6/
https://leehamnews.com/2019/02/01/bjorns-corner-pitch-stability-part-7/
https://leehamnews.com/2019/02/08/bjorns-corner-pitch-stability-part-9/
https://leehamnews.com/2019/02/15/bjorns-corner-pitch-stability-part-10-wrap-up/
per chi avesse tempo e (soprattutto) voglia o per chi soffre di insonnia e cerca un metodo per addormentarsi :very_drunk:, raccomando la letture dei "Corners" di Bjorn Fehrm, analista aeronautico molto esperto anche in temi aerodinamici. Sul sito leehamnews ha una rubrica dedicata alla pitch stability, analizzata in conseguenza al crash della Lion Air e ripresa dopo il crash del volo Ethiopian. Sono articolo molto interessanti che descrivono in maniera sintetica ma esaustiva la dinamica e lo sviluppo della stabilitá attorno all´asse orizzontale per un aeromobile e la interazione dei vari elementi della struttura, dall´ala presa come parte singola indipendente ai motori stessi.
Colgo inoltre l´occasione per farvi i complimenti, ho trovato una marea di informazioni e spunti interessanti in questo thread. Grazie a tutti per questa discussione.
https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopian-airlines-flight-302-crash/
https://leehamnews.com/2018/11/23/bjorns-corner-pitch-stability/
https://leehamnews.com/2018/11/30/bjorns-corner-pitch-stability-part-2/
https://leehamnews.com/2018/12/07/bjorns-corner-pitch-stability-part-3/
https://leehamnews.com/2018/12/14/bjorns-corner-pitch-stability-part-4/
https://leehamnews.com/2019/01/11/bjorns-corner-pitch-stability-part-5/
https://leehamnews.com/2019/01/18/bjorns-corner-pitch-stability-part-5-2/
https://leehamnews.com/2019/01/25/bjorns-corner-pitch-stability-part-6/
https://leehamnews.com/2019/02/01/bjorns-corner-pitch-stability-part-7/
https://leehamnews.com/2019/02/08/bjorns-corner-pitch-stability-part-9/
https://leehamnews.com/2019/02/15/bjorns-corner-pitch-stability-part-10-wrap-up/
Articolo interessante, scritto per un pubblico di profani
https://www.newyorker.com/news/our-columnists/how-did-the-faa-allow-the-boeing-737-max-to-fly
La notizia che FAA ha delegato una parte della procedura di autorizzazione del B737 MAX a Boeing e' apparsa anche sul Times di oggi. Mi sa che passera' un po' di tempo prima che il 737 Max ritorni a volare
https://www.newyorker.com/news/our-columnists/how-did-the-faa-allow-the-boeing-737-max-to-fly
La notizia che FAA ha delegato una parte della procedura di autorizzazione del B737 MAX a Boeing e' apparsa anche sul Times di oggi. Mi sa che passera' un po' di tempo prima che il 737 Max ritorni a volare
Domanda da non addetto ai lavori (e chiedo venia se fosse già stata postata). Possibile che questo evento non si sia presentato in altre occasioni senza avere esiti catastrofici come nel caso di Lion e Ethiopian?
A conti fatti, solo il volo precedente a quello fatale di Giacarta ha sofferto della stessa dinamica, mi par solo strano che non se ne siano verificati altri.
A conti fatti, solo il volo precedente a quello fatale di Giacarta ha sofferto della stessa dinamica, mi par solo strano che non se ne siano verificati altri.
I DAR (Designated Airworthiness Representative) esistono ‘da sempre’ e presso tutti i costruttori di qualsiasi cosa che necessiti di approvazione FAA,
e quindi io mi stupisco dello stupore generale…
e quindi io mi stupisco dello stupore generale…
mi sembrava di aver letto lo stesso da qualche parte. chiedo lumi, grazie mille
Interessanti aggiornamenti su AvHerald
http://avherald.com/h?article=4c534c4a&opt=0
On Mar 18th 2019 The Aviation Herald learned that flight ET-302 was cleared to follow the SHALA2A standard departure route after departure from runway 07R and was cleared to climb to FL360. According to ground observers the departure was uneventful, the aircraft was handed from tower to departure (=approach) control where the aircraft was cleared to track directly to waypoint RUDOL when able. The crew however requested to maintain runway heading and climb to 14,000 feet advising of a flight control problem, which was approved by departure control. Some moments later the crew requested to return to Addis Ababa (in a routine like voice), departure cleared the flight to turn right heading 260, the crew replied "stand by, stand by". The aircraft continued on runway heading, the climb appeared to be very fast initially. Departure advised the crew they were flying into a restricted zone HA (R)-1, the call was without reply. The "standby" reply by the crew proved to be the last transmission from the aircraft. Radar contact was lost from both primary and secondary radar (the secondary radar was operating in degraded mode). An arriving 787 flight was asked by approach control to overfly the area at 17,000 ft where the radar had lost contact with the aircraft, the crew of that flight however did not see anything while searching for 15 minutes. A smaller training aircraft was dispatched and found the wreckage. The source stressed, that there had been no PAN PAN or MAYDAY call, there was also no change in transponder code away from the assigned code 2000, there had been no indication of unreliable airspeed by the flight crew, there had been no distress in the voices or abnormal background noises during transmissions from the aircraft that would have alerted air traffic control to assume a serious problem on board of the aircraft. Maximum altitudes and speeds have not been reported (editorial remark: a media report had claimed the contact with the aircraft was lost at 10,800 feet MSL).
Following the Nov 6th 2018 release of the Boeing Bulletin regarding MCAS in the aftermath of the crash of the LionAir the airline did distribute the bulletin to their flight crew a number of days later following a reminder. Ethiopian Airlines had been equipped with one Boeing 737-700 NG simulator only when the first MAX aircraft were put into service, the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).
The source added the B737 NG simulator was not able to reproduce different trim handling by both aircraft: on the NG aircraft automatic trim (e.g. by the SRS) could be counteracted by an (intuitive) elevator opposite control input (e.g. on a nose down trim a nose up elevator input would stop and disable the autotrim system) unless a double failure was inserted by the sim instructor whereas on the MAX the intuitive counter acting elevator input no longer stops the automatic trim in order to permit MCAS to work. The only means to disable automatic trim on the MAX is therefore the trim cutout switches (renamed PR and D/U) below the throttle quadrant on the center console (same location as on the NG), which completely disables all electric trim (also via the trim switches at the controls) and leaves the crew with manual trim via the trim wheel only, so that crew needs to rotate the trim wheel nose up promptly to recover from a stabilizer nose down trim introduced by an automatic trim (e.g. by MCAS or other faults).
The source also reported continuing on runway heading (072 degrees magnetic), respective in a corridor around 080 degrees keeps the aircraft over relatively flat terrain and is used as the go around procedure for runway 07L/R. To the south or north terrain rises. HA (R)-1 would not have posed a problem due to terrain, it is a military restriction. The aircraft was in visual meteorologic conditions throughout the flight.
http://avherald.com/h?article=4c534c4a&opt=0
On Mar 18th 2019 The Aviation Herald learned that flight ET-302 was cleared to follow the SHALA2A standard departure route after departure from runway 07R and was cleared to climb to FL360. According to ground observers the departure was uneventful, the aircraft was handed from tower to departure (=approach) control where the aircraft was cleared to track directly to waypoint RUDOL when able. The crew however requested to maintain runway heading and climb to 14,000 feet advising of a flight control problem, which was approved by departure control. Some moments later the crew requested to return to Addis Ababa (in a routine like voice), departure cleared the flight to turn right heading 260, the crew replied "stand by, stand by". The aircraft continued on runway heading, the climb appeared to be very fast initially. Departure advised the crew they were flying into a restricted zone HA (R)-1, the call was without reply. The "standby" reply by the crew proved to be the last transmission from the aircraft. Radar contact was lost from both primary and secondary radar (the secondary radar was operating in degraded mode). An arriving 787 flight was asked by approach control to overfly the area at 17,000 ft where the radar had lost contact with the aircraft, the crew of that flight however did not see anything while searching for 15 minutes. A smaller training aircraft was dispatched and found the wreckage. The source stressed, that there had been no PAN PAN or MAYDAY call, there was also no change in transponder code away from the assigned code 2000, there had been no indication of unreliable airspeed by the flight crew, there had been no distress in the voices or abnormal background noises during transmissions from the aircraft that would have alerted air traffic control to assume a serious problem on board of the aircraft. Maximum altitudes and speeds have not been reported (editorial remark: a media report had claimed the contact with the aircraft was lost at 10,800 feet MSL).
Following the Nov 6th 2018 release of the Boeing Bulletin regarding MCAS in the aftermath of the crash of the LionAir the airline did distribute the bulletin to their flight crew a number of days later following a reminder. Ethiopian Airlines had been equipped with one Boeing 737-700 NG simulator only when the first MAX aircraft were put into service, the first 737-8 MAX simulator was put into service mid January 2019. Only in March 2019 a trim runaway lesson was included in the NG and MAX training syllabus. Flight crew are scheduled to go through a simulator session every 6 months (as per industry standards), the accident flight crew may thus not yet have received training on a stabilizer trim runaway (in the NG or MAX Simulator).
The source added the B737 NG simulator was not able to reproduce different trim handling by both aircraft: on the NG aircraft automatic trim (e.g. by the SRS) could be counteracted by an (intuitive) elevator opposite control input (e.g. on a nose down trim a nose up elevator input would stop and disable the autotrim system) unless a double failure was inserted by the sim instructor whereas on the MAX the intuitive counter acting elevator input no longer stops the automatic trim in order to permit MCAS to work. The only means to disable automatic trim on the MAX is therefore the trim cutout switches (renamed PR and D/U) below the throttle quadrant on the center console (same location as on the NG), which completely disables all electric trim (also via the trim switches at the controls) and leaves the crew with manual trim via the trim wheel only, so that crew needs to rotate the trim wheel nose up promptly to recover from a stabilizer nose down trim introduced by an automatic trim (e.g. by MCAS or other faults).
The source also reported continuing on runway heading (072 degrees magnetic), respective in a corridor around 080 degrees keeps the aircraft over relatively flat terrain and is used as the go around procedure for runway 07L/R. To the south or north terrain rises. HA (R)-1 would not have posed a problem due to terrain, it is a military restriction. The aircraft was in visual meteorologic conditions throughout the flight.
si è corretto, da tenere presente che la velocità letta dall'impianto statica/dinamica (pitot/presa statica) viene corretta in base all'assetto dell'aereo rispetto all'aria, ovvero l'angolo d'attacco (sonda AOA). Se questa è bloccata o comunque invia dati per qualunque motivo errati la conseguenza è avere differenza di velocità indicata nei rispettivi PFD (due impianti distinti per la lettura della velocità rispetto all'aria). Questa differenza di velocità è ovviamente "vista" anche dall'impianto autopilota, che non potendo discriminare quale tra i due dati è quello corretto, si disinserisce se era ON o non è possibile inserirlo se era OFF.
Altra discriminante è il flap, se l'equipaggio leggendo alto valore di speed retrae il flap si hanno le condizioni perchè MCAS diventi attivo, risultato finale sarà sistema MCAS che se legge valori prossimi allo stallo per alto AOA= comando di nose down a velocità reale bassa e flap up
In pratica se selezioni una tacca di fraps sfanculi il mcas e porti l'aeroplano a casa sano e salvo (a costo di fare una overspeed dei flaps/slats, ma sarebbe il minimo)?
Cioè esistono casi in cui l'MCAS si può attivare anche se l'autopilot è disattivato?