The 737max disaster!

Ok i do like a bit of aviation well the tech side and crash investigations.

Anyway have you seen now there are so many 737max's they're parking them in the Boeing staff carparks

Its a bit of a Brexit conundroum to fix them too, if you haven't read too much, the crux is their inherent aero dynamic instability. The answer was MCAS (an anti stall feature due to the position of the engines and aero profile caused the aircraft to potentially nose up without warning and stall.) And MCAS prevents this by activating a nose down routine to prevent stall, all well n good until a simple sensor fails and the plane thinks it is stalling and instead nosedives into the ground killing everyone of course hence the grounding of these jets.

Now.. the simple solution would be to disable the MCAS system or make it easy to disable but then it makes the plane unsafe i refer you back to the aero design issues.

Will be fascinating (well for some anyway) how Boeing get themselves out of this mess.




Read more here

https://bit.ly/2KDHpcH

BA have just announced they are buying a load. My understanding from talking to a few pilots in my sailing club, is that a lot of modern aeroplanes are unstable and need computer controls anyway.

If you have ever tried to get your head around Health & Safety in general then surely you have heard of the Flixborough Disaster.

The 737max has most of the classic symptoms & most of the classic causes of why such disasters can & always will occur.

As always, we will accept any official inquiries findings & take them at their 'forked tongue' word that such a thing cannot & will not ever happen again.

The following from Chris Brady :- http://www.b737.org.uk/sales.htm

"The Boeing 737 is the best-selling commercial aircraft in aviation history over 15,000 aircraft ordered."



List of the 172 B737 write offs - from same website.
http://www.b737.org.uk/accident_reports.htm
A quick skim doesn't reveal many from US airlines... COULD it be somewhat of a pilot thing ? Besides the iffy gear.
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Brian Hayes has been ruminating...
http://bit-player.org/2019/737-the-max-mess

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The bottom line is that the 737 MAX is a very different plane from the original 737. Even the landing gear had to be re-designed to reduce the risks of tail strikes when taking of and landing. This and other significant changes to the design should have required a completely new approvals process by the Federal Aviation Authority ( FAA ) for the 737 MAX.

Instead the changes were down graded to enhancements and as such a full approvals process was avoided and the "grandfather" approval for the 737 family was extended to cover the 737 MAX.

Boeing and the FAA are jointly responsible for the 737 MAX getting an Airworthy Certificate when the differences between 737 and 737 MAX and some design errors and omissions were enough to make the 737 MAX as delivered to some airlines a dangerous thing to fly.

I see tonight on Ch4 there's coverage on the 737max titled 'what went wrong' it's a bit of a recap on the 2 fatalities and some simulations on what happened, perhaps not what you want to be watching if you're off travelling shortly!

Just to add to this if you haven't seen snippets in the news the growing concern of Boeing and their cost cutting conduct in other areas such as the oxygen packs in the dreamliner series and i feel their too cozy relationship with the FAA, it's a concern.

Re the 737 max It still comes back to the fact Boeing wanted to ensure this plane stayed desirable to the commercial market so they fudged things with software to keep it classified as a 737 (no new training required!) when in reality they should of made structural changes to the engine position to fix the aerodynamic stability issues.

An aircraft with positive stability will return to its original position when it is displaced from a neutral position, either instantaneously (static stability), or over time (dynamic stability). At high angles of attack, the 737 MAX’s engine nacelles create enough lift to cause a divergent mode, which pitches the nose up and exacerbates the nose up moment. This is an example of both negative static and dynamic stability, both which are extremely dangerous characteristics for a passenger aircraft. These issues make stall recovery extremely difficult without an electronic “fix”.

Because of the 737 MAX’s inherent instability issues, the elevator authority necessary to easily effect a stall recovery is likely exceeded at high AOA’s. Therefore, Boeing chose to develop an electronic “bandaid” to attempt to solve the problem. Enter the MCAS, or Maneuvering Characteristics Augmentation System, which will apply nose down trim if the autopilot is off, the flaps are not extended, and the AOA exceeds a preset level. This is a highly unusual “fix”, one that had not been designed into any other conventionally flight controlled airliners. It ignored one of most basic principles of problem solving: “Whenever you solve a problem, you usually create one. You can only hope that the one you created is less critical than the one you eliminated.” If it’s a good solution, the newly created problem will be far smaller (and acceptable) than the problem that was just solved. This was not true of MCAS. It created a far greater problem (possible loss of aircraft pitch control), than the one it solved (nose-up pitching moment at high AOA).

So from here there are two solutions:

A) Fudge it with more redundant sensors and software, and be nice to the FAA.
B) Build a new fuselage and wings to adjust the profile and fix the stability issues without the need of software.

Fiver says which one they go for!

Fit a manual override to mcas

How bad is the "instability" (without the bodge MCAS operating)?

What I'm asking is, would fooking the bodge off and actually allowing pilots to fly the thing be a realistic option?

The risk is you go in to a stall too easily. So the nose is pushed down.

Brigadier said:

How bad is the "instability" (without the bodge MCAS operating)?

What I'm asking is, would fooking the bodge off and actually allowing pilots to fly the thing be a realistic option?

Click to expand...

The real reason behind the use of MCAS was that it allowed the 737Max flying characteristics to be very similar to the previous model so no need to recertify pilots and extra training at huge cost.

You drop the MCAS your going to have to retrain all the pilots in new flight simulators etc.


2.30m in

Before you say wouldn't it be cheaper to just train all the pilots up. Well there is only "one Max simulator in airline hands in North America — at Air Canada"

Who do you think is at fault?

OK,

What is the likelihood of a pilot not stalling it in the first place?
By "pilot", I mean someone who's experience isn't weighted towards simulators, as appears to be the case in modern times.

The pilots were not aware the MCAS existed so when things were going wrong, they had no idea of the cause

Brigadier said:

OK,

What is the likelihood of a pilot not stalling it in the first place?
By "pilot", I mean someone who's experience isn't weighted towards simulators, as appears to be the case in modern times.

Click to expand...

As doug99 points out above if the pilots were unaware of MCAS they were operating off the wrong SOP which reinforced the problem resulting in two crashes.

Let's hope Boeing never goes into the driverless car business!

SirGalahad said:

As doug99 points out above if the pilots were unaware of MCAS they were operating off the wrong SOP which reinforced the problem resulting in two crashes.

Click to expand...

That wasn't what I asked about, though.

Is the plane unflyable without MCAS?
If not inherently so, was it just the cost of proper training that made MCAS the chosen "solution"?