737 Max8. Safe or not safe?

[Kayos]

Not read the whole thread but I have just read an article that basically said the aircraft is a 60's design rather than brand new and having to move the more efficient engines further out caused problems. This was rectified with the system that is being (possibly) blamed for the crashes

 

[ajlelectronics]

Not read the whole thread but I have just read an article that basically said the aircraft is a 60's design rather than brand new and having to move the more efficient engines further out caused problems. This was rectified with the system that is being (possibly) blamed for the crashes

Rectified is the wrong word. A better one is "disguised". The CoG was put out of limits by the new engine position which makes it tail heavy. That makes a wing stall much more likely so the computer is supposed to keep an eye on the AoA and prevent a stall. Although I don't know all the technical details, I believe that the computer relies solely on one (as standard) AoA sensor and has no other information about airspeed or anything else. Consequently when it is asked to imitate a homesick angel, the computer says "no". Or if the AoA sensor is damaged as is alleged in the last incident it may try to prevent a stall that is not imminent.

 

[jimbo84]

Looks like they've got the update ready.

https://www.bbc.co.uk/news/business-48276232

 

[Tobymonster]

Here's a good (although long) article about the design decisions and why they implemented them on their 737 Max8 aircraft.

https://www.bbc.co.uk/news/resources/idt-sh/boeing_two_deadly_crashes

It does skimp on a few details, like it implies that there is only one Angle of Attack sensor, but there are actually two either side of the cockpit, but only one is feeding a flight computer at a given time, so there is no redundancy when one fails. Also there is only a display of the readings of both not AoA sensors if a very expensive option was bought, something the budget airlines would not do. Finally there is supposed to be a warning light that would operate if there was a disagreement between the two that would warn the pilots if something was wrong, but Boeing have admitted this would not work unless the expensive option was taken......ouch.

Also, the attitude correction system, or MCAS, adjusted the angle of the horizontal stabilizer. The whole of the horizontal tail plane moves on big screw jack, so small movements on a big surface will give massive adjustments in pitch. Pilots can only counteract this by large movements into the relatively smaller elevators, by pulling back on the control column until they hit the stops. Then they have to use the trim wheels but it's something like 30 turns to cancel one MCAS input. And every few seconds the computer pushes the nose down again and again and again.

Finally my speculation here, Boeing were producing 52 B737 max8's a month, that's nearly 2 a day before they were grounded. The focus is on damaged Angle of Attack sensors by bird strikes or being hit by jet bridges, but it could be wiring issues during assembly. It would take much to snag a wire whilst fitting a galley, or a rogue cherry max rivet tail (that should of been vacuumed out but not due time constraints), shorting in an electrical terminal on the AoA system.

I'm not anti Boeing, they will fix these issues and I may even fly or work on them, but it's definitely time for a brand new design.

 

[p0689109]

Years ago when the airbus A320 first came on the scene(Freddie Laker was the launch customer with the only 10 MK1's shall we say which BA bought when he went bust) which originally came without the winglets. Boeing realising they had a serious competitor went on a savage weight saving campaign to keep their models competitive. One of the areas they trimmed weight was on the APU combustion chamber end cap. One day I went to investigate a problem with the apu and as I lowered the shroud to have a look with the apu running there was a gaping hole in the flame tube! No fire alarm triggered but could have caused a nasty incident as sometimes the crews used to leave the apu running when they left the a/c and the aircraft not always continued flying that day and so it could be left on for hours! Competition in markets is a good thing but there are boundaries but dollar signs can blinker the reality.

 

[jimbo84]

Seems like they’re going the way of everything nowadays and looking at profit above everything else. So much for the safety comes first line the aviation industry always quotes.

 

[roofman]

Years ago when the airbus A320 first came on the scene(Freddie Laker was the launch customer with the only 10 MK1's shall we say which BA bought when he went bust) which originally came without the winglets. Boeing realising they had a serious competitor went on a savage weight saving campaign to keep their models competitive. One of the areas they trimmed weight was on the APU combustion chamber end cap. One day I went to investigate a problem with the apu and as I lowered the shroud to have a look with the apu running there was a gaping hole in the flame tube! No fire alarm triggered but could have caused a nasty incident as sometimes the crews used to leave the apu running when they left the a/c and the aircraft not always continued flying that day and so it could be left on for hours! Competition in markets is a good thing but there are boundaries but dollar signs can blinker the reality.

Freddie Laker there's a name from the past..did,nt he start by running a fleet one elevens and Tenerife being one of the routes, then started doing long haul with the DC10 and brought cheap long distance holidays to the great unwashed when before we all could only dream of having a cold beer in Florida

 

[brightspark]

Freddie Laker there's a name from the past..did,nt he start by running a fleet one elevens then started doing long haul with the DC10 and brought long distance holidays to the great unwashed were before we all could only dream of having a cold beer in Florida

yep and british airways put him out of business for undercutting them and dirty tricks

 

[p0689109]

Goes on in all businesses though, buying out the opposition.

 

[KemppiFrog]

Freddie Laker there's a name from the past..did,nt he start by running a fleet one elevens and Tenerife being one of the routes, then started doing long haul with the DC10 and brought cheap long distance holidays to the great unwashed when before we all could only dream of having a cold beer in Florida

He didn't start there, much earlier..
Well worth a read: https://en.wikipedia.org/wiki/Freddie_Laker

 

[roofman]

He didn't start there, much earlier..
Well worth a read: https://en.wikipedia.org/wiki/Freddie_Laker

wow he did have an outstanding CV in aviation

 

[marlinspike]

We were due to fly to Mallorca on one after the accident. I was pretty worried and was very relieved when the UK eventually grounded them. We got a Dreamliner on the way out by way of replacement. I would not knowingly book a holiday with an airline that used Max's.

 

[Tobymonster]

^^^ Do you not remember the trouble Boeing had with the overheating batteries that the B787 Dreamliner had? Problems do get engineered out and people forget. I'm due to go on a Dreamliner next week.

 

[jimbo84]

Wasn’t there a 787 that went up in smoke on the tarmac due to the batteries? Seem to remember them engineering some kind of fireproof box for the batteries as well as re-engineering the batts themselves. Lithium ions I think.

 

[Tobymonster]

Yep. It was an Ethiopean B787 at Heathrow. But that time it wasn't the main batteries that overheated it was the battery in the Emergency Locator Transmitter near the rear galley. The whole of the tail of the aircraft was replaced in a specially built temporary hangar by Boeing themselves. The fuselage is all composite and not aluminium alloy.

 

[Bullet2012]

https://www.bbc.co.uk/news/business-48752932
Seems it’s not ready yet

 

[CoValent]

Well worth a read: https://en.wikipedia.org/wiki/Freddie_Laker

...attended the Simon Langton Grammar School for Boys, from which he was expelled, before starting work in aviation...

I warmed to him immediately I read that.

 

[Brad93]

Wasn’t there a 787 that went up in smoke on the tarmac due to the batteries? Seem to remember them engineering some kind of fireproof box for the batteries as well as re-engineering the batts themselves. Lithium ions I think.

I used to make said boxes

 

[cardiffrob]

I work for Bruce Dickinson (Iron Maiden) and we got called in on Tuesday to do a Channel 5 filming thing on 'why Trump chose a 747 as his new Airforce One when it is such an old design'. Without prior warning I gave Bruce an engine failure and an engine fire, killing both engines on one side, just as we took off from New York (I did mention it was a Sim, didn't I?) and it flew on as if nothing had happened. After climbing to 10,000 feet he spiralled it down to do a single-pilot approach off of a tight turn to replicate the sort of evasion technique used to spoof missiles.
That 747 is built like a brick whatsit-house and has impeccable manners. Try that sort of thing in a 737 and you'd be a smoking hole in the ground. I've also got to say that Bruce can still fly very nicely, for an old fart.

 

[Seadog]

I've only flown with him once. Back from the Caribbean I think.