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How Boeing, FAA certified the suspect 737 MAX flight control system

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Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#11

Post by Insanity »

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.”

How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense.

Or perhaps they did, and they just really look like similar planes. In which case I wonder if the threshold for 'versioning' should be changed.

(I know nothing of how this actually works, it just baffles me that seemingly different planes get the same certificate)

EDIT: I read the FAA does check this, but I wonder on what _grounds_ it makes the decisions.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#12

Post by mcv »

Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

It makes sense that very minor differences don't require extra training if the differences have no meaningful impact on cockpit design or flight characteristics. But in this case, flight characteristics were clearly different, and MCAS was supposed to compensate for those differences.

I don't know how they measure such differences, but you'd think that different engines, different aerodynamics, and a new control system to compensate for those differences, are enough to warrant a new type certification.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#13

Post by saluki »

Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

y, sounds like a change like this:

The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations.

Would require more training than a few hours.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#14

Post by ams6110 »

Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

More and more of this has been delegated to the manufacturers themselves.

They simply assert to the FAA that the aircraft meets the type requirements.

Boeing showed the FAA their test results, said that with MCAS the aircraft meets requirements, doesn't require extra training, and the FAA took their word for it. Authorities in most other countries trust the FAA, so they took their word for it too.

That's an oversimplification, but more or less what happened.

As to whether Boeing was deliberately deceptive, we'll probably find out in due time as investigations have begun and subpoenas issued.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#15

Post by VBprogrammer »

saluki wrote: post #13
Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

y, sounds like a change like this: The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations. Would require more training than a few hours.

Do you have a citation for "incorporated because the plane...has a chance of facing a stall at lower speeds than earlier 737 variations".

I think you may have misread something. Normally stalling at a lower speed is a good thing.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#16

Post by resoluteteeth »

VBprogrammer wrote: post #15
saluki wrote: post #13

Earlier quoted context omitted.

y, sounds like a change like this: The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations. Would require more training than a few hours.

Do you have a citation for "incorporated because the plane...has a chance of facing a stall at lower speeds than earlier 737 variations". I think you may have misread something. Normally stalling at a lower speed is a good thing.

I don't think the comment you are responding to means "the speeds at which it will stall are lower compared to earlier 737 variations," but rather "at low speeds, it has a greater chance of stalling compared to earlier 737 variations."

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#17

Post by pdonis »

saluki wrote: post #13
Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

y, sounds like a change like this: The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations. Would require more training than a few hours.

> has a chance of facing a stall at lower speeds than earlier 737 variations

No, that's not the issue. The issue is that, because of the pitch up moment created by the engines, at higher angles of attack the force required to move the yoke decreases instead of increasing. That's (a) a highly undesirable characteristic since the changing feedback confuses pilots and makes it hard for them to know when a stall is imminent, and (b) a violation of FAA certification requirements. MCAS was added to compensate for the pitch up moment from the engines by adding nose down trim, so the yoke force would be similar to that of previous 737 models.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#18

Post by pdonis »

resoluteteeth wrote: post #16
VBprogrammer wrote: post #15

Earlier quoted context omitted.

Do you have a citation for "incorporated because the plane...has a chance of facing a stall at lower speeds than earlier 737 variations". I think you may have misread something. Normally stalling at a lower speed is a good thing.

I don't think the comment you are responding to means "the speeds at which it will stall are lower compared to earlier 737 variations," but rather "at low speeds, it has a greater chance of stalling compared to earlier 737 variations."

It doesn't matter which of those two the poster meant; they're both wrong as descriptions of the effect of the new engines on the 737 MAX. See my other post upthread.

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#19

Post by [deleted] »

saluki wrote: post #13
Insanity wrote: post #11

>, “Boeing 737-800 pilots were required to receive some additional training on the MAX 8, which included an hour lesson on some differences. Additional training was not required, as the 737-800 and the MAX 8 have same type certification.” How are those type certifications determined? It seems to me that there should be an instance checking if the type certifications make sense. Or perhaps they did, and they just real…

y, sounds like a change like this: The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations. Would require more training than a few hours.

[deleted]

Re: How Boeing, FAA certified the suspect 737 MAX flight control system

#20

Post by ams6110 »

pdonis wrote: post #17
saluki wrote: post #13

Earlier quoted context omitted.

y, sounds like a change like this: The system, known as the Maneuvering Characteristics Augmentation System, or MCAS, was incorporated because the plane has larger engines placed further forward on the craft, and so has a chance of facing a stall at lower speeds than earlier 737 variations. Would require more training than a few hours.

> has a chance of facing a stall at lower speeds than earlier 737 variations No, that's not the issue. The issue is that, because of the pitch up moment created by the engines, at higher angles of attack the force required to move the yoke decreases instead of increasing. That's (a) a highly undesirable characteristic since the changing feedback confuses pilots and makes it hard for them to know when a stall is immin…

You're correct, however without MCAS it could be easier for the pilot to accidentally pitch into a stall when flying manually. That is why the requirement for consistent feedback, as you say. So the people who say the MAX engine placement makes it "more prone to stall" are not entirely wrong.

The media has done a poor job of communicating exactly what MCAS does and why it was developed. With today's media motivated by virality, ad clicks and eyeballs, most seem more interested in reporting this as dramatically as possible.

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