MCAS in detail on the 737 MAX

This presentation takes a close look at the details of MCAS on the 737 MAX, how it came about, what changes were made and how it now works.
This presentation does not discuss the management decisions by Boeing, the FAA oversight, the blame games or the regulations put into place since the accidents. This is all covered in my first presentation “The 737 MAX and MCAS from development to fix” which is available on my KZbin channel.
Contents
0:00 Intro & How and where did MCAS come from
3:25 The low speed problem
6:34 Aerodynamic Solutions
9:39 How was MCAS adapted for low speed?
10:33 The effect of MCAS on stick force gradient
13:12 The MCAS accidents
17:21 Why & how was the IAS and Alt affected?
19:58 The FCCs, STS & MCAS
22:40 The changes to MCAS
31:36 Actions beyond fixing MCAS
39:31 Why did the fix take so long?

[@stm3252]

I'm an aircraft maintenance engineer endorsed on the Max and I learned a lot of new stuff from your channel. Kudos to you for the pertinent information provided, it's beyond informative! Thanks

[@ChrisBrady737]

My pleasure, thanks for watching.

[@scottgbourke]

Super Job Chris. Thanks for taking the time to make that for us.

[@ChrisBrady737]

Glad you enjoyed it!

[@jibeneyto91]

Thank you very much for sharing this Chris. Your video, together with the previous one describing the accidents, is now my "go-to" source of information on MCAS.

[@ChrisBrady737]

Thanks for watching

[@sorabjvariava1442]

Great Job Chris, and the last statement of open and honest safety culture and not succumbing to commercial pressures sums it up.

[@ChrisBrady737]

Thank you Sorab, let us hope that Boeing change this.

[@bmused55]

A very detailed and great overview. No bias, no bullshit. Just facts. Thank you! Subscribed :)

[@ChrisBrady737]

Exactly what I was aiming for, thanks.

[@telescope64]

A very detailed,technical explanation. Thank you for collating and explaining all this information.

[@ChrisBrady737]

Glad it was helpful.

[@tiemji]

Thanks for this great and detailed presentation about the MCAS on the 737 Max, really nice to see facts and not only opinions 👍🏾👍🏾👍🏾👍🏾

[@ChrisBrady737]

Thank you for your kind comments, glad you found it useful.

[@GabrielEngle]

Excellent presentation. I learned a ton as always. Muchas gracias Captain!

[@ChrisBrady737]

My pleasure.

[@barrysheridan9186]

Thank you for your explanations.

[@dinamiena6186]

Great presentation as always. Thank you Captain!

[@ChrisBrady737]

Thank you, you are very welcome

[@iliassidiropoulos9610]

GreatJob Chris Congratulations!

[@ChrisBrady737]

Thanks Ilias

[@josecorreia1189]

Excellent presentation, thank you very much Captain Chris

[@ChrisBrady737]

My pleasure, thanks for watching.

[@jtmuzix]

This is an awesome channel and I'm not sure how many more videos you have planned BUT the more the merrier. Me personally would be interested in the computer systems and data busses- I believe its only ARINC 429 for the 737 but being wrong is not new for me. :) Anyway yeah, I've very much interested in the computer systems / digital avionics of aeroplanes.

[@ChrisBrady737]

Hi, thanks for your kind comments. I have already covered the computer systems in the video "737FMC" kzbin.info/www/bejne/mICYnalue6uKe9E and also the associated videos covering the various software updates. Enjoy!

[@josecorreia7416]

Thank you very much for sharing this information, outstanding presentation

[@ChrisBrady737]

My pleasure, thanks for watching

[@Alex-hx2sz]

Wonderful explanation sir. Thanks!

[@ChrisBrady737]

That is great to hear, thank you for your support. Please tell your colleagues.

[@drstevewright6175]

Excellent - many thanks.

[@ChrisBrady737]

You are welcome!

[@hanssamson5436]

Great Presentation! Also I am flying on the 737 max 8 to Vancouver from Toronto almost a 5 hour flight starting on 13th April!

[@ChrisBrady737]

You need have no concerns about flying on a MAX. The MCAS issues are all resolved.

[@hanssamson5436]

@@ChrisBrady737cheers captain, I will enjoy flying on it!

[@hanssamson5436]

@@ChrisBrady737 hello captain I have a question, do the 737NG and the MAX behaves differently for the pilot control and is it similar to control the NG to the MAX?

[@Anupcobainful]

Hi Chris this is awesome amazing , really good

[@ChrisBrady737]

Glad you like it, thanks for watching

[@ilarikousa1500]

Thank you so much!

[@ChrisBrady737]

You're welcome!

[@nicolareffo2661]

Thanks

[@nicolareffo2661]

I am retired now but I flew the 767. So did I have MCAS too and didn’t know?

[@ChrisBrady737]

I don't think that the civilian 767 had MCAS, I think it was only the KC-767A/KC-46 that had it.

[@ChrisBrady737]

Thank you very much, much appreciated.

[@anthonyglee1710]

Great video, glad I found your channel. I work in IT development for a global company and it would be unthinkable to NOT have x3 or x4 hardware redundancy. I just cannot understand Boeings oversight which is glaringly obvious in hindsight. Similarly and I’m focusing on AF447, why isn’t GPS used as an additional check for speed, laterally and vertically?

[@ChrisBrady737]

Thanks Luca, glad you like it. The main problem with GPS speed is that it is a groundspeed not an IAS. Some Boeing types have synthetic airspeed I believe that this uses GPS speed in its calculations somewhere.

[@agsadgs]

Because if you want to add a new AOA senser, you must add a new ADIRU. That means it need a brand new system for the new 737. So in the 737 max 10 they use 2 AOA senser and a eAOA from the ADIRU to get triple AOA data and not need a brand new system. The ADIRU can calculate the AOA but the GPS can't.

[@petep.2092]

What is the third AOA value used for? So much money wasted pretending to fix what ain't broke, and playing charades and giving intellectually dishonest demos in flight simulators… just to hide the fact that two airlines were not giving their pilots the basic training required for the 737 type rating and between them they killed 346 people. Why the cover up? And the cherry on the top- pontificating about lives lost in the pursuit of financial gain. So much for integrity.

[@petep.2092]

You can't understand it but it is glaringly obvious in hindsight? Nice! So you now have an obvious non-understanding of Boeing's oversight, whatever that may be. As long as you are arrogant enough to believe that the knowledge and understanding you have in one field enables your understanding of another complex field by substituting common sense for the specialized education required, your understanding of that complex field will be plausible nonsense. But since it seems plausible to others with common sense, it will be easily accepted as the truth, even by you; enough that you will feel comfortable passing judgement and condemning others. It's captured by the adage: Little knowledge is a dangerous thing. Stick to IT until you get an education in aeronautical engineering. Maybe get one in IT too, you might learn that redundancy is provisioned to the level needed, not per some daft blind rule; you can make a system less reliable by providing too much redundancy.

[@ChrisBrady737]

@petep.2092 I am not sure who your comments are aimed at but please keep the debate good natured. There is no need to descend to that level 👍

[@christerry1773]

Great job. I’ve always been confused about the feel unit, basically this caused the force to double what it would normally be…? Wouldn’t there have been a way to deactivate that unit, possibly pulling one of the circuits? Assuming it was overhead and not on the back wall

[@ChrisBrady737]

There was and is no way to deactivate the unit. More details are in my Flight Controls - Pitch video.

[@christerry1773]

@@ChrisBrady737 another Boeing logic fail. How could they not have seen the disaster coming!

[@aviatortrevor]

If the pilots in the 737-MAX crashes used their electric pitch trim on the yoke every 5 seconds, would they both prevent MCAS activation and be able to trim the aircraft back into a normal stable state?

[@ChrisBrady737]

Probably

[@Milkmans_Son]

Wouldn't a near stall still be outside the normal flight envelope, or no?

[@ChrisBrady737]

It depends how near, but yes it would.

[@puneetbhardwaj8322]

Hi..it's MDS in max and CDS in NG..chk typo errors

[@ChrisBrady737]

Yes, you are right

[@jimmylu9156]

Would you have references for this information?

[@ChrisBrady737]

I don’t provide references in the videos. Please treat your company manuals as the authoritative source of information.

[@marktaylor2087]

Are you from Stoke?!

[@ChrisBrady737]

No, Liverpool. Why did you think that?

[@marktaylor2087]

@@ChrisBrady737 ohh, interesting. I'm from Stoke and the way you sound your vowels is pretty similar. People from Stoke often get asked if they're from Liverpool ironically. Great video btw.

[@a.nelprober4971]

Chris sorry for being lazy but can you link just the presentation please?

[@ChrisBrady737]

I don't understand what you mean by "link just the presentation". I have provided a timed list of contents in the description.

[@a.nelprober4971]

@@ChrisBrady737 just the .PowerPoint for future reference without having to watch the video. I wanted to share it with someone who doesn't have time to watch the full thing.

[@ChrisBrady737]

I am not going to make my presentations available for somebody who "doesn't have the time to watch the full thing". They can watch the video in parts, the contents are all timestamped to allow viewers to do this. If they want a "lite" version of this information then other less in-depth sources are available on the internet.

[@a.nelprober4971]

@@ChrisBrady737 I did not mean to come across as rude. Thanks for all the time and effort you put into making this content.

[@ChrisBrady737]

That’s ok, I hope you are finding them useful. I will be updating the book soon which your colleague may find easier to dip in and out of. Best regards

[@paulwolf8444]

Liked the presentation, but isn't this all kind of like using magnets to flip the dice, to pass the test, on an inherently unstable airframe. It's one thing to let the military develop mcas for its tanker configuration, people sign up to to take risks in the military. A lot of people know that those engines and their placement makes the airframe unstable and easily be demonstrated. This new plane should have been marketed as having come from Rube Goldberg inc.

[@ChrisBrady737]

I go into detail on the concealment of MCAS in a separate video "The 737 MAX and MCAS from development to fix". I have since read a comment from an FAA employee who has said that MCAS may not have been needed at all. Who knows exactly what the truth is?

[@paulwolf8444]

@@ChrisBrady737 i had watched after the first crash on a news program about that crash in which they had on a retired pilot who also was an engineer as their expert commentator. In the segment he discusses the differences between the old 737 and max and described how the size and more importantly the placement of the engine would affect the flight characteristics and when this airframe would experience trouble. Turns out he's right. The flight contol issues that mcas is addressing are the same ones as described by an outside engineering perspective that was observed early on. I'm thinking I probably would not trust someone who says mcas might not have been needed unless it's from the camp that says halt production we got fix this the right way.

[@petep.2092]

How is the airframe inherently unstable? And please DO demonstrate how the engines and their placement makes the airframe unstable. Or would that be MORE unstable as it is already unstable? I'm eager to hear.

[@paulwolf8444]

@petep.2092 You should ask the veteran pilot and also an engineer who was on television news early on when this wholesale debacle started. He actually described when this configuration might encounter trouble, and as it turned out, that was the target of the Maneuvering characteristics augmentation system. Ps It's It's not just the placement but also the increased thrust.