Boeing 737 Max8 Aircraft Crashes and Investigations [Part 7] 16

[Sparweb]

This post is the continuation from this series of previous threads:

thread815-445840
thread815-450258
thread815-452000
thread815-454283
thread815-457125
thread815-461989

This topic is broken into multiple threads due to the length to be scrolled, and images to load, creating long load times for some users and devices.
If you are NEW to this discussion, please read the above threads prior to posting, to avoid rehashing old discussions.

Thank you everyone for your interest! I have learned a lot from the discussion, too.

Some key references:
Ethiopian CAA preliminary report (Link is now broken. See PDF download below, 3 MB)

Indonesian National Transportation Safety Committee preliminary report

A Boeing 737 Technical Site

Washington Post: When Will Boeing 737 Max Fly Again and More Questions

BBC: Boeing to temporarily halt 737 Max production in January

www.sparweb.ca

 

[waross]

Let's step back and look at the overall picture.
I am not sure of the correct terms so feel free to correct my terms.
Is it time for the regulators to address changes in stability resulting from engine offset from the center of gravity?
As one suggestion, but not the only one, what would be the effect of limiting the effect or authority of the stabilizer to a value that may be overcome by manual trimming at maximum forces?
I am dismayed by my understanding of the FAA ruling that the excess manual trim forces are OK because there is no regulation as to the maximum force allowable.
We have started to discuss the possible effect of the failure of MCAS to operate when it is needed.
Now how about the unavailability of manual trim when it is needed.
Come on FAA.
If there is no regulation, that is not an excuse. It is another instance of mission failure and a wake-up call to develop a reasonable regulation, without regard to the effect on the MAX.
I wonder if those already mostly completed MAX craft can be absorbed into the freight haul market?
They are efficient and they will probably be cheap.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

A question for the aviation experts.
With engine thrust tending to push the nose up, and the stabilizer trying to hold the nose down, is this causing a noticeable increase in fuel consumption, compared to an engine position that does not cause an uplift force?
I am not advocating that engine position, I am trying to find out how much increase fuel consumption is caused by a large engine displacement.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[waross]

As instructed, the Ethiopian pilots hit the cutoff switches that killed power to the horizontal tail, stopping its movement. But then they found they couldn’t physically move the tail to a nose-up position by rotating a manual wheel in the cockpit.

The FAA said that “simulator predictions validated by Boeing flight testing” were used to calculate the required trim wheel forces and that a mockup of the manual wheel demonstrated that with these procedures it could be moved even by smaller crews with less physical strength.

?????
I am sure that Boeing and the FAA can reconcile these statements.
However can that be done without setting off every BS detector within range?
Please explain what changes were made to the manual system so that at maximum stabilizer runaway at maximum speed, the manual trim wheel may now be moved by even smaller crew members.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Alistair_Heaton]

The more the trim stab is pushing down the more fuel is burnt. The moment off the engine decreases the amount of trim stab required if it is forward and lower than the CoG.

We try and organise the load so that the CoG is towards the rear of the envelope to minimise it during cruise.

But you do get a noticeable difference in fuel burn. The fuel plan includes 3-5% extra to account for it.

Turning an aircraft into a freighter is a major mod. A big door has to go in, fire system and floor strengthened.

Personally I think they should go back to the NG and have one switch to kill the automatics but leave the electric trim working via thumb switch. And another to completely kill the power to electric trim.

 

[waross]

Thank you Alistair.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Alistair_Heaton]

looking at the MAX orders it looks like they have already made the ones required for the USA Market. About 800 are required.

I believe they have over 500 in stock parked up.

The major orders from US operators are Air southwest, United, AA and Alaskan. The last one has issues because it will need to fly through Canadian airspace.

By far the largest orders are from leasing firms which usually require the aircraft to be able to go anywhere in the world.

I have been thinking along the same lines as the last few posts.

If MCAS is critical and required then there is very little safe guards to prevent you ending up without it. I presume the crew can turn it off just by killing one of the flight control computers.

If its deemed not critical flight envelope protection then you don't need it anyway.

I suppose it all centres around what alpha it actually starts kicking in anyway. Its turned off anyway when the flaps are out. So its not active during approach and only really comes on during 4th segment of climb after TO. Which only really leaves windshear and various escape procedures although windshear you would expect some level of flap to have been put out when you get it.

With that in mind and the relative ease now it gets turned off what's the point of having it anyway? There is a reg on control forces but if the system to control then gets killed when virtually any downgrade occurs then its pretty pointless.

To add the minimum equipment list is going to be interesting. There are going to be a whole heap of items not on it which on the NG you could go flying because they were listed which now have to be functioning because it kills the MCAS system. The NG has a great dispatch record with this key system requiring pretty much everything functioning thats going to suffer

 

[Alistair_Heaton]

seems there is a heap of poo about the FAA going on.

Must admit I have been taking that as a second political issue apart from the regulation side of things

Seems its the same issue as NASA with challenger. Again lesson not learned and loads of lives lost

https://www.seattletimes.com/busine...survey-say-top-managers-have-pro-boeing-bias/

 

[dik]

From the news:

It’s been approximately 12 million years since most of us last used a floppy disk, but apparently, the antiquated tech still plays a critical role in delivering software updates to Boeing’s 747-400 planes.

The discovery comes courtesy of cybersecurity firm Pen Test Partners and was initially spotted by The Register. As part of this year’s virtual DEF CON hacker conference, Pen Test Partners showed off a video walkthrough of a British Airways 747 after the airline decided to retire its entire fleet last month due to the global pandemic. The roughly 10-minute tour is a neat glimpse into the plane’s rarely seen avionics bay and cockpit—where Pen Test Partners discovered a 3.5-inch floppy disk drive.

Dik

 

[moon161]

Sure, wouldn't surprise me a bit to see one on one of the CNC machines where I work. I wouldn't be too surprised to see one or a comparable magnetic media device on an F-22.

 

[Eufalconimorph]

Magnetic media is surprisingly reliable. It doesn't degrade the way optical media like CDs do, and has a much longer life when unpowered than Flash (which loses its state slowly with time).

Also, the 747 is an old aircraft. Why change something that you don't need to, that provides no safety benefit from upgrading?

 

[LittleInch]

Also it's been said earlier in the threads here that the FCCs are based on ancient technology so can't handle large amounts of data.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Lou Scannon]

remember when PCs came even without a hard disk? You needed your own floppy boot disk with an OS to even use the PC. I wonder if the the 747 captains have their personal boot disk in their flight bags in order to get the A/C to an operational state?

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[waross]

The 3 1/2" floppies are still available on Amazon. Many are noted as "Discontinued by the Manufacturer".
Does anyone remember the 8" floppies? They were often referred to as "Mass memory".
There were a lot of formats but I understand that they maxed out at 1.2 MB.
There were a number of news reports last October:

Air Force finally retires 8-inch floppies from missile launch control system
"Solid state storage" replaces IBM Series/1's floppy drive.
Sean Gallagher - 10/18/2019, 8:37 AM

The 3 1/2" floppies were modern technology by comparison.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[IRstuff]

I still have one 8" floppy for posterity, but not the drive. I recall our PDP-10 minicomputer at work had a such a floppy for hard reboots. Note that it was only for the boot loader program; the OS resided on the hard drive, but at the time, there was apparently no way to get it to boot directly off the HD.

Obviously, that clearly solved by the time HDs were standard equipment on PCs.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[Alistair_Heaton]

There is a whole raft of old tech out there that uses various obsolete OS's and ports to interface with various bits of kit.

Some of it is OEM's going out of business, some of it is people trying not to have to pay the cost for the new software.

Also by changing the data input method you then trigger a recertification process.

Most of the new stuff uses flash memory cards and can be accessed from the flight deck in the maint panel. And you can update everything from there including the FEDEC's in the engines.

There has been a few times in the last 18 years that there has been a huge panic because the RS232 serial cable is broken or the windows 3.11 laptop has gone down.

 

[1503-44]

My first floppy 5-1/4 inch had 180k capacity and in 1981 that was a pretty hefty lift. Processor had 28k, also considerably high for its time.

I'm thinking this website needs a feature to load threads from last post at top to first post last at bottom. My screen protector is getting worn and ragged on the right side now.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[LittleInch]

If you manage to be able to click on thee "new" label it takes you to the new threads

Also at the top of the thread there is a "read new threads" button. Saves your thumb action

But that's why this thread is now at part VII

Need a part VIII sparweb? we're at 282 replies and we ain't done yet on this one I think.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Compositepro]

ax1e, if you click on the "new" icon next to the the topic title, you will be taken straight to the first new post since your last visit. Once you have entered a thread you can also click on "read new posts".

 

[IRstuff]

My recollection is that my first computer, as well as the Osborne One, one of the first "portable" computers, had around 80k or 90k capacities. You pretty much had to have two drives because you needed one for the application itself, and the other to store data from the application.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[dik]

My first 2D Frame program, I wrote, swapped to those floppies and ran in 16K RAM... They were about $30 per box of 10 while the 360K diskettes were about $50.

Dik