Another (2nd) 737 Max 8 crash

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#2208098 31-Mar-2019 11:43

The A350's chemistry isn't publicly known but it's energy density and operating voltage is lower than the 787's pack which would indicate it's not the same cobalt chemistry that was quite widely known for its thermal runaway issues, Whilst not a reason to 100% not use it the pack should have come from the factory with the changes that were later made around containment and isolation.

We'll never know if the A350's pack was designed better at the start or rather in response to the 787 issues however given the time difference it's possible Airbus was intending to use a less armoured pack but quickly redesigned it after the 787 issues. It will be interesting to see how the Airbus overboard vent handles in an actual emergency

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#2208582 1-Apr-2019 12:35

https://finance.yahoo.com/news/prosecutors-probe-whether-boeing-misled-162829234.html

"Federal prosecutors are investigating whether Boeing provided incomplete or misleading information about its best-selling 737 Max aircraft to U.S. air safety regulators and customers, according to a report from The Wall Street Journal.

It’s reportedly part of a larger investigation into how the aircraft was developed and certified, according to the Journal. Boeing has faced escalating pressure since two of its new 737 Max jets crashed in under five months.

The criminal investigation began last year, after the aircraft was involved in a Lion Air crash that killed 189 individuals. Five months later, at the beginning of March, one of Boeing’s new Max jets operated by Ethiopian Airlines crashed, killing 157 people. U.S. regulators have not connected the two incidents but suggested there are similarities."

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#2209787 2-Apr-2019 21:21

Prob. not worth a new thread but Singapore Airlines has grounded two B787 10 aircraft - with the Trent 1000 TEN engines. Premature blade cracking.

(Rolls Royce have also been involved in developing engines for the new Royal Navy destroyers. These engines can't handle the heat when operating in very hot climates such as the Persian Gulf.)

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#2209822 2-Apr-2019 22:39

The Royal Navy was forced to use these Rolls Royce gas turbines by the British Government. It seems that most ships of a similar size to these destroyers use a marine gas turbine based on the design of a Airbus A330 engine.

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#2209881 3-Apr-2019 05:45

amiga500:
The Royal Navy was forced to use these Rolls Royce gas turbines by the British Government. It seems that most ships of a similar size to these destroyers use a marine gas turbine based on the design of a Airbus A330 engine.

Airbus don't make aircraft engines.

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#2209888 3-Apr-2019 06:46

Technofreak:
amiga500:
The Royal Navy was forced to use these Rolls Royce gas turbines by the British Government. It seems that most ships of a similar size to these destroyers use a marine gas turbine based on the design of a Airbus A330 engine.

Airbus don't make aircraft engines.

Neither do Foton, but that doesn't mean I can't design an engine based on the engine in a Foton Tunland ute.

Unless the A330 doesn't have an engine, then it would be pretty hard to copy the design ;)

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#2209991 3-Apr-2019 09:34

Ge0rge:
Technofreak:
amiga500:
The Royal Navy was forced to use these Rolls Royce gas turbines by the British Government. It seems that most ships of a similar size to these destroyers use a marine gas turbine based on the design of a Airbus A330 engine.

Airbus don't make aircraft engines.

Neither do Foton, but that doesn't mean I can't design an engine based on the engine in a Foton Tunland ute.

Unless the A330 doesn't have an engine, then it would be pretty hard to copy the design ;)

Perhaps I could have been a little bit clearer.

Airframe manufacturers usually offer a variety of engine choices, the A330 was fitted with engines from three manufacturers, GE, P&W and RR.

The poster was being critical of Rolls Royce engines and was suggesting the use of a variant of the engines used in the A330 but didn't say which one they were talking about.

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#2209998 3-Apr-2019 09:52

Technofreak:The poster was being critical of Rolls Royce engines and was suggesting the use of a variant of the engines used in the A330 but didn't say which one they were talking about.

It is probably unfair to characterize this as a Rolls Royce problem. At 1st glance it seems like a proven turbine design mated to a Northrop Grumman intercooler-recuperator that has a major design flaw. Northrop Grumman were the prime contractor responsible for system integration.

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#2210088 3-Apr-2019 13:00

https://ukdefencejournal.org.uk/type-45-not-the-royal-navys-fault/

This article gives more background about the Rolls Royce WR-21 engine. Among other interesting facts the ukdefencejournal article mention that RR has deleted all reference to the WR-21 from their website. It's still available on a web archive page.

At around the time decisions were being made on the Daring Class destroyer the Royal Navy had around 41 admirals, many of whom prob. advocated for the well proven LM2500 engine. This engine has been used in so many naval vessels that there are more classes of ships in which it is used, than the number of WR-21 engines ever made by Rolls Royce! (Maybe around 20!)

While RR can't be blamed for all the problems with this botched and rushed project, it proves what a flawed decision making process the Brits. had.

Getting back to the issue of the B787 Trent 1000 TEN engines, I hope Air NZ has now adopted a more sceptical view of advice from Rolls Royce.

It is very fortunate that so far there has not been any loss of life caused by failures in these Trent 1000 engines.

(The FAA was very concerned that failure of one engine would result in the other engine having to be used at high thrust settings for a long time & could result in failure of the second engine. Far from ideal when Air NZ were flying the Southern Ocean route to South America. Less of a problem for the European operators flying over Europe with a myriad of suitable runways available in an engine emergency.)

After the news of groundings by Singapore Air of two of their B787 with the 'new and improved' engines, I imagine Air NZ will be very anxious...

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#2210451 4-Apr-2019 05:27

Looks as though the Ethiopian Airline pilots may have switched MCAS off (as per the Boeing guidelines), and started using the handwheel to trim the aircraft.
Then, possibly because they were having trouble using manual trim, switched it back on to re-enable trim thumb switches on the yokes.
OR.. it switched itself back on - which is a worry..

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#2210511 4-Apr-2019 07:54

amiga500:

After the news of groundings by Singapore Air of two of their B787 with the 'new and improved' engines, I imagine Air NZ will be very anxious...

No they won't be.

The "ïssue" highlighted by Singapore Airlines isn't actually new despite some claims of this.

Issues with the TEN were well known to RR and the industry as a whole in the middle of last year, and it was pretty much acknowledged then that the TEN was not a magic fix for all of the Package C issues as some had believed once they began to actually understand what had causes the failures of the blades. Remember the TEN was not a fix for the Package C engine issues - it was merely a newer version of the same engine with performance improvements.

New redesigned blades were approved by the FAA and EASA and introduced in January this year for Package C engines, and a redesigned TEN blade is also part of these plans.

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#2210560 4-Apr-2019 09:37

sbiddle:

amiga500:

After the news of groundings by Singapore Air of two of their B787 with the 'new and improved' engines, I imagine Air NZ will be very anxious...

No they won't be.

The "ïssue" highlighted by Singapore Airlines isn't actually new despite some claims of this.

Issues with the TEN were well known to RR and the industry as a whole in the middle of last year, and it was pretty much acknowledged then that the TEN was not a magic fix for all of the Package C issues as some had believed once they began to actually understand what had causes the failures of the blades. Remember the TEN was not a fix for the Package C engine issues - it was merely a newer version of the same engine with performance improvements.

New redesigned blades were approved by the FAA and EASA and introduced in January this year for Package C engines, and a redesigned TEN blade is also part of these plans.

That's interesting I wasn't aware of that. I guess only time will tell how good the new blades really are.

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#2210576 4-Apr-2019 10:03

Sidestep:

Looks as though the Ethiopian Airline pilots may have switched MCAS off (as per the Boeing guidelines), and started using the handwheel to trim the aircraft.
Then, possibly because they were having trouble using manual trim, switched it back on to re-enable trim thumb switches on the yokes.
OR.. it switched itself back on - which is a worry..

I get sceptical of articles like these as there are glaring mistakes in what they print. It is obvious the writer doesn't know what they are writing about and in some cases is putting their own uneducated opinion into the article.

From the article linked above;

The so-called MCAS anti-stall software is at the center of accident probes in both the Ethiopian crash and October’s Lion Air accident in Indonesia that have together killed 346 people.

MCAS was designed to help prevent an aerodynamic stall by issuing commands to push the plane’s nose lower.

MCAS IS NOT an anti stall software. It is not designed to prevent a stall. It is there to augment control forces.

Then there is this little gem from that same article. I have no idea what it means and I bet the writer had no idea what they were writing about either.

causing the MCAS software to begin lowering the nose to grab air under the wings.

Once the trim switches are turned off there is no way for the system to turn itself back on. So no need to worry about that.

According to that article the crew likely turned the system back on plus it seems that crew didn't follow the correct procedure prior to initially turning it off.

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#2210595 4-Apr-2019 10:27

Technofreak:

MCAS IS NOT an anti stall software. It is not designed to prevent a stall. It is there to augment control forces.

It's more than that, in that it trims the nose down beyond what the pilot has requested with stick force.

Once the trim switches are turned off there is no way for the system to turn itself back on.

How do you know this? Do the trim switches directly control current to the trim actuators, or are they just inputs into the computer? Even if the former, presumably the computer would still need to know that it couldn't control the trim, otherwise it might issue commands to the inactivated trim system in conjunction with commands to other devices e.g. the auto-throttle.

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#2210647 4-Apr-2019 11:34

frankv:

Technofreak:

MCAS IS NOT an anti stall software. It is not designed to prevent a stall. It is there to augment control forces.

It's more than that, in that it trims the nose down beyond what the pilot has requested with stick force.

Once the trim switches are turned off there is no way for the system to turn itself back on.

How do you know this? Do the trim switches directly control current to the trim actuators, or are they just inputs into the computer? Even if the former, presumably the computer would still need to know that it couldn't control the trim, otherwise it might issue commands to the inactivated trim system in conjunction with commands to other devices e.g. the auto-throttle.

The MCAS is designed to increase the required stick forces in certain circumstances to help avoid the pilot over controlling (pitching) the aircraft.

What computer are you talking about? The 737 isn't a Fly By Wire aircraft. There is no computer for the trim system.

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