Incidente Ethiopian ET302 B737 MAX 8
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Sí PAUL, sono con te, con rivisitazione sostanziale intendo una miglioria di quel che già c'è. Ormai i motori ce li han messi là sotto. Il Max resterà, e magari riescono a girare la frittata e a farne un aereo ok. Che poi non ne ha già due pure il 73? O ricordo male? Perché non l'hanno attaccato pure all'altro se così. Dovevano mettercene un terzo anzi!
In pratica però, parlando del caso specifico, di sonda ne esiste solamente una perché MCAS prende il segnale da una sonda per volta e le sonde si “switchano” automaticamente ad ogni de-power ( un po’ come LGCIU 1 e 2 su Airbus, anche se per tutt’altro sistema,*per intenderci ).*
Questo sistema, così come è concepito, ti garantisce il 50% di possibilità di un intervento di*MCAS in caso di unreliable speed, fenomeno*che peraltro diventata esponenzialmente più probabile con 2 sole sonde.*
Geniale.
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Ecco la soluzione Boeing
Così su due piedi, senza saper leggere né scrivere, sembra ragionevole. In attesa di smentite/altri punti di vista
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Dai preliminari dell'FDR sembra che abbiano staccato i cutout per poi reinserirli in quanto non riuscivano a trimmare nose up con l'handwheel ? Immagino per resistenza aerodinamica ?
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E avrebbe anche senso. Così vicino a terra non hai il tempo di tirare fuori la manovella e girarla. Non ho mai verificato, ma mi pare che servano 10 giri per trimmare un unità di stab trim. Se erano a 0 e dovevano portarla a 4 o 5 unità, con la trim wheel che non è quella di un cessnino, non ci sarebbe tempo a sufficienza.
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La Boeing ha fatto un meeting a Seattle dove sono stati invitati tutti i clienti max dove è stato spiegato cosa è stato fatto per risolvere il “ Problema “
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https://www.aviationcv.com/aviation-...mcas+ethiopian
altro articolo , ci stiamo orientando “casualmente “ verso l errore umano e inesperienza
altro articolo , ci stiamo orientando “casualmente “ verso l errore umano e inesperienza
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Non mi risulta sia stato ancora pubblicato il preliminare, qualcuno, in caso contrario, può indicare dove poterlo scaricare?
O forse semplicemente Ethiopian ha avuto accesso a dati non ancora ufficialmente pubblicati?
O forse semplicemente Ethiopian ha avuto accesso a dati non ancora ufficialmente pubblicati?
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In alto a destra!
Home - civilaviation
Home - civilaviation
Last edited by RunBoyRun; 4th Apr 2019 at 19:53. Reason: Title change
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così sembra volessero convincere gli operatori a Seattle*
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2 INITIAL FINDINGS
On the basis of the initial information gathered during the course of the investigation, the following facts have been determined:
3
The Aircraft possessed a valid certificate of airworthiness;
The crew obtained the license and qualifications to conduct the flight;
The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
After autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.
On the basis of the initial information gathered during the course of the investigation, the following facts have been determined:
3
The Aircraft possessed a valid certificate of airworthiness;
The crew obtained the license and qualifications to conduct the flight;
The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
After autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.
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2 INITIAL FINDINGS
On the basis of the initial information gathered during the course of the investigation, the following facts have been determined:
3
The Aircraft possessed a valid certificate of airworthiness;
The crew obtained the license and qualifications to conduct the flight;
The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
After autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.
On the basis of the initial information gathered during the course of the investigation, the following facts have been determined:
3
The Aircraft possessed a valid certificate of airworthiness;
The crew obtained the license and qualifications to conduct the flight;
The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
After autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.
JF
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Takeoff roll began from runway 07R at a field elevation of 2333.5 m at approximately 05:38, with a flap setting of 5 degrees and a stabilizer setting of 5.6 units. The takeoff roll appeared normal, including normal values of left and right angle-of-attack (AOA). During takeoff roll, the engines stabilized at about 94% N1, which matched the N1 Reference recorded on the DFDR.
From this point for most of the flight, the N1 Reference remained about 94% and the throttles did not move.
From this point for most of the flight, the N1 Reference remained about 94% and the throttles did not move.
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Voi mi spiegate il significato degli ultimi decenni di aviazione, dove siamo stati bombardati di reports di incidenti concludenti bene o male sempre l' implicito 'pilot error' , con poi conseguenti corsi di crm, e power point infarciti di acronimi surreali suppostamente atti a identificare tutte le deficienze e lacune di noi miseri operatori che, si sa, siamo sempre l'anello debole, e che "la catena non è forte che quanto il suo anello debole" , e quindi vai di TEM , che guai a non menzionare la complacency quando torni alla base perché rischi grosso etc etc, e poi, loro, a monte, dalle loro scrivanie aeronautiche divine FAA, con poi decine di teste super intelligenti a lavorare in unisono, quali di certo sono gli ingegneri Boeing, l'elite dell'elite della conoscenza aeronautica, sotto richieste impartite dal rispettivo management, in un ambiente dove il time constraint non è di minuti / ore come il nostro, ma bensì anni, riescono infine a partorire un tale aborto di sistema. Ora chi glielo farà, a loro, alla Boeing e alla FAA, il corso TEM CRM con power point dagli acronimi salvatori previeni-errori?
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Da una lettura piuttosto veloce del preliminary mi sembra che la situazione si sia particolarmente deteriorata dal fatto che l'equipaggio abbia re-ingaggiato i cutout ed abbiano mantenuto sempre le manette a spinta di decollo. Il tutto ovviamente al netto di un sistema MCAS le cui interazioni ed i relativi casini lasciano a bocca aperta.
