Do You Remember The Previous Post About Boeing Plane Crashes

[kenj]

They were originally designed with pure jet engines which were no problem. When, for fuel economy, they changed to turbofan engines they had to re-design the cowling at the bottom for ground clearance. You will note the flattening at the bottom. The newest engines just compounded the ground clearance problem. https://aviation.stackexchange.com/q...les-odd-shaped

I wondered why the kept developing it, probably the best twin engined jet ever made, but showing its age a bit.

Ken

[zqwerty]

They kept developing it to avoid a complete new aircraft design, as in the Airbus 320, and save money by not having to re-certify.

That's where they came unstuck, new management teams unlike the older ones from Boeing's past management pushing the engineering design team into modifications that in the end were bad engineering and potentially would cause plane crashes.

Happens all the time, management trying to save money through compromising the original good design.

The R&D lab where I worked called it "cutting out the fat" although that was mostly the cost accountants pushing those changes.

[tweak'e]

They were originally designed with pure jet engines which were no problem. When, for fuel economy, they changed to turbofan engines they had to re-design the cowling at the bottom for ground clearance. You will note the flattening at the bottom. The newest engines just compounded the ground clearance problem. https://aviation.stackexchange.com/q...les-odd-shaped

I wondered why the kept developing it, probably the best twin engined jet ever made, but showing its age a bit.

Ken

but the change in engines doesn't make it "inherently unstable". it fly's like any other passenger jet.
they have had numerous engine changes over the years. the new ones are the high bypass type which are a bit bigger than the previous turbofan engines.

[tweak'e]

They kept developing it to avoid a complete new aircraft design, as in the Airbus 320, and save money by not having to re-certify.

yes, and also reducing the amount of re-training required which saves air lines a lot of money.
using an existing well proven platform is a good method. pretty common in all industries.

its the screwing up of mcas system and hiding info from the FAA etc is where it all went wrong.

[tweak'e]

Boeing have admitted they were to blame, the plane was faulty.

now this is your conspiracy bit.

the plane is not faulty. the original MCAS system was most certainly was and Boeing are most certainly to blame for that and have copped some massive fines over it. the faulty MCAS system caused crashes and Boeing wil pay the price for that.

but the plane flies perfectly fine as its a stable aircraft.
its still being produced and there is large amounts of orders for them. why? because the plane is not faulty.


you need to remember that this is not uncommon. a part is found to be poorly designed/made/etc and they replace that part. they don't scrap the whole plane just over one part.
if they did that there would be no planes flying ever.

[zqwerty]

MCAS was designed for 737 MAX, it is not on any other 737's, it was designed to control the MAX's tendency to nose up and eventually stall if correction was not applied continuously by the pilots or MCAS itself must be operating to do the correcting. This nosing up was caused by too big engines mounted forward and higher than where they should be to compensate for poor ground clearance. The MCAS was poorly implemented both in a hardware and software context and inadequate instructions were given to pilots on how to over-ride its operation if there were problems.

MCAS was an attempt to make the MAX "feel" to the pilots just like previous 737 variants, and to cover up the tendency to nose up if left to normal control by pilots.

Read this:

https://en.wikipedia.org/wiki/Maneuv...ntation_System

[B.M.]

It’s a great pity that this once great Company should fall into disgrace like this.

[tweak'e]

MCAS was designed for 737 MAX, it is not on any other 737's, it was designed to control the MAX's tendency to nose up and eventually stall if correction was not applied continuously by the pilots or MCAS itself must be operating to do the correcting.

almost ALL passenger aircraft have "tendency to nose up and eventually stall if correction was not applied continuously".
yep even your modern airbus do that.
that is normal for ALL low mounted wing, underslung engine aircraft.
that is why you have a pitch trim setting to go with the power setting, which is normal SOP for almost all large passenger aircraft.

plus the MCAS does NOT apply continuously. it ONLY gets used at the very limit of flight operation. ie it only applies correction when the plane goes to max AOA. as that is rarely ever done in normal flying, it pretty much does nothing at all.
once again, you can throw out the MCAS system and the plane will fly perfectly fine. its not required for flight.
in fact the fault procedure is to turn it off and fly without it. the plane flys perfectly fine without it.

your showing your complete lack of understanding how aircraft actually fly. trouble is most of the media don't understand either, hence the conspiracy theory thats been pushed.

[zqwerty]

The planes that crashed were heading towards the ground instead of climbing during takeoff which the pilots tried to stop by pulling back on the stick and bringing the nose up. MCAS was overcompensating because the sensor, (only one was designed into the input of MCAS by Boeing even though two were available), was sending back faulty data to the MCAS input, this sensor was known to fail in this way.

The pilots didn't know how to turn off the MCAS, didn't even know of its existence, apparently, they physically couldn't overcome the MCAS faulty correction (pointing the aircraft nose down because all indication to the MCAS said the aircraft was on the verge of stalling) for any length of time physically speaking.

If they could have turned off the faulty MCAS the plane would resume to normal but extreme nose up behaviour, as you say, remember the plane was climbing after taking off.

The faulty MCAS flew the plane into the sea or land when the error occurred unless the pilots knew how to turn MCAS off.

The plane always had a larger nose up tendency than normal that is why MCAS was included, to make the plane behave like a normal 737 the pilots usually flew, instad of giving the pilots extra training on the MAX which was not like a normal 737 variant.

[zqwerty]

continued,

this was done to save money and time as has been mentioned before.

So as you say the MAX may have behaved well enough without MCAS but was different enough from normal 737 variants to warrant Boeing including MCAS to make the plane behave predictably to the pilots.

I'll concede that the plane may not have been very unstable with MCAS switched off but would have been different to what the pilots were used to (wanting to climb more severely than normal and increase the AoA) with a plane they usually flew, requiring attention to different nose up behaviour and therefore different trim settings.

This is why MCAS was included in the first place to avoid having the pilots deal with a flight behaviour they were unfamiliar with.