Boeing 737 Max8 Aircraft Crashes and Investigations [Part 8] 24

[Sparweb]

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

thread815-445840
thread815-450258
thread815-452000
thread815-454283
thread815-457125
thread815-461989
thread815-466401

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 from Ethiopia is now broken. See link from NTSB Investigations below)

Indonesian National Transportation Safety Committee preliminary report

NTSB Investigations

NTSB Safety Recommendation Report: Assumptions Used in the Safety Assessment Process and the
Effects of Multiple Alerts and Indications on Pilot Performance

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

Pulitzer Prize, For groundbreaking stories that exposed design flaws in the Boeing 737 MAX that led to two deadly crashes and revealed failures in government oversight.

http://www.sparweb.ca

 

[1503-44]

Then you're farther back from the window and field of view is more restricted.

 

[Sparweb]

why rear-projection HUDs instead of up-projection onto the windscreen?

The windscreen is made to a very particular shape, unique to every aircraft type, with materials that already have a very specific purpose.
I don't think it would be easy to make a projector that could project a display onto the complex curvature of a windscreen and maintain an appearance of orthogonality to the pilot's point of view.
Any error in the projector's position, or movement of the pilot's head could break the angle. Change pilot and you can't adjust position of the projector.
Last time I saw an airliner's windshield being replaced, I remember about 1/8" of gasket to allow for mis-match of surface contour with the window frame.
The projector for any other aircraft would need its own lens/software transformation.
And getting the reflection to work... what membrane or coating is applied to that surface?
Do they work at severe angles?
You know that on the other side of the 20mm thick window pane it's -50C outside?

http://www.sparweb.ca

 

[Alistair_Heaton]

You have a viewing angle of about +-1 deg on the HUD to be able to see all the information.

Pilot head position/eye line is critical for low viz approach's with or with out a HUD.

 

[verymadmac]

The other issue with projecting on the windscreen is that it distorts in flight. Even the 1" thick armoured glass in WWII fighters was found to distort excessively in flight preventing the projection of the gun sight straight onto the windscreen.

 

[Comcokid]

Not to mention that the windscreens already consist of multiple layers so they can incorporate a heating layer, impact resistance for bird strike, scratch resistance on the surface, and are carefully designed so you don't have multiple reflections because of all the layers. If you add a reflective layer for a HUD you're likely to end up with a lot of reflections under other lighting conditions where you aren't using the HUD.

The windscreens are already very expensive and I don't think they need any additional issues or they would be unaffordable. At that point they would just replace the windscreen with metal skin and use an AI to fly the plane.

 

[Alistair_Heaton]

If your interested in the a220 windo looks like close up

 

[Sparweb]

Is the diffraction pattern (rainbow) visible to the eye or just your camera that picks it up?

Any thoughts or experience using a wearable EVS (helmet/goggles/visor/variety of types) rather than projected on a HUD?

http://www.sparweb.ca

 

[zeusfaber]

Is that not a polarisation effect?

A.

 

[Alistair_Heaton]

yes you can in certain lighting conditions. And you tend not to see it straight ahead but when you look across the cockpit at the other sides windows.

It also changes with the temperature gradient.

It was a lot more pronounced on the Q400.

I think its due to the heating element grid in the window. Those windows get very hot, a lot hotter than any other type I have flown. Even when its -60 degs outside you wouldn't want to hold your hand on them.

I have no experience of helmets or NVG tye display's, mates that have used them in the military all suffer from neck issues of one form or another due to the weight of them. They also say NGV etc is an extremely perishable skill and takes a fair amount of work to get up to speed on.

Most airlines that use HUD's make it a bit of a fiddle to reduce maint costs. They only get the LH side fitted with them and then don't keep the machine rated for dual flight director low viz approaches.

 

[IRstuff]

Most airborne optical windows heaters are only designed to provide sufficient heat to keep from frosting, i.e., to keep the window pane at about 5 C or so, which is still makes it close to freezing temperature. For a jet, the power density is supposed to be around 4.26 W/in^2, but that also depends on what the craft is flying through.

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 are some of them that the window needs to be warm for bird strikes, the Jetstream 31/32 was like that. If it was cold it didn't pass the turkey test fired at it with big air gun. And it was a no fly if it wasn't working.

As I say this thing is running significantly hotter than anything else I have experience with. The reason why its the way it is I have no clue. There is usually a cold area somewhere in the cockpit which you learn not to put your hand near with direct metal connection to the outside of the airframe on most types. The DV window handle on the Jetstream you would stick to if you touched it. I haven't found one yet on this thing. The floor has electrical heaters in them for your feet in front of the rudder pedals. As you rightly say normally they are just enough to stop them frosting up. These things can melt chocolate.

 

[Alistair_Heaton]

Back to the MAX.

Might be some movement soon.

A load of technicians are getting pulled over to Canada next month for Boeing training on the MAX I presume to do the fixes. I can only presume the trainers will be sitting in Quarantine for two weeks before they start. Or maybe there will be a room of Ipads for them to read ;-)

There is still loads of rumours about the 3rd AoA input into the whole setup and if it will be a deferred addition or required for flight outside the USA. Currently the MAX doesn't comply with the 1 in 1 million rule and neither does the NG for its STS system but as they have such a good safety record with it its not being included in the scope ie it's proved by flying more than 1 million hours without a failure. But you can kill it without loosing the electric trim.

 

[dik]

Latest?

The FAA said the Joint Operations Evaluation Board for the Boeing 737 MAX will take place at London Gatwick Airport and meet for approximately nine days “to review Boeing’s proposed training for 737 MAX flight crews” and will include civil aviation authorities and airline flight crews from the United States, Canada, Brazil and the European Union.

There are several other key steps to be completed that raise questions about if there will be any 737 MAX commercial flights before 2021.

This week in Vancouver, the European Union Aviation Safety Agency conducted flight tests of the Boeing 737 MAX after Canada conducted its own tests.

Dik

 

[FacEngrPE]

I doubt this will be the last word from congress, perhaps a start?

Press Release
September 16, 2020 After 18-Month Investigation, Chairs DeFazio and Larsen Release Final Committee Report on Boeing 737 MAX

https://transportation.house.gov/ne...ease-final-committee-report-on-boeing-737-max

Link to the report
FINAL COMMITTEE REPORT THE DESIGN, DEVELOPMENT & CERTIFICATION OF THE BOEING 737 MAX SEPTEMBER 2020
PREPARED FOR: CHAIR OF THE COMMITTEE ON TRANSPORTATION AND INFRASTRUCTURE PETER A. DEFAZIO AND CHAIR OF THE SUBCOMMITTEE ON AVIATION RICK LARSEN BY MAJORITY STAFF OF THE COMMITTEE ON TRANSPORTATION AND INFRASTRUCTURE

 

[Sparweb]

Getting through the first pages, it's a fairly political report. Maybe that's what's needed, hard to say. If it reflects the view that the certification system would work if Boeing had played by the rules and the FAA had enforced them, then it would support the opinion that has formed in my mind over the year. I hope the style settles down after the bluster is exhausted. It's a long read. Just the executive summary is almost 30 pages long!

http://www.sparweb.ca

 

[Alistair_Heaton]

Seems like its a third point of the triangle saying its not our fault its the other two.

And what we put in place shouldn't be changed especially if we have to provide more money for it.

I think I lost count at 7 for these committee report things going and to be honest mainly because I realised they were pretty much toothless and political show boating.

I suspect the only changes will occur when the international bodies decide what the next era's rules are going to be. The FAA and Boeing will have to make a choice of comply or have to certify twice.

The 777x program must be in a right mess just now.

 

[davefitz]

I think the report states only the obvious, while leaving out how the congress usually influences the actions of the regulators in deference to the regulated industry. In the case of a US airline manufacturer, it is the normal course of business for the FAA to impose a ruling that might delay production, then the mfr complains or lobbies their congressional representative, and then that representative talks tough to the FAA's politically appointed leadership, who then backs off the difficult ruling. The report would be more informative if it included details of politicazl interference in its actions.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[Alistair_Heaton]

Any lobbying and changes of a ruling should be made public.

If there is a ruling and the OEM fixes it then nothing needs to enter into the public domain.

 

[rb1957]

I still say we should put a time limit on type certificates, maybe 20 years (how much production of the original type is happening after 20 years ?)

If you want to continue production then you need to update the certification to the current rules.

It is clear (now) that the critical issue with the B737 is that the wing is too low for these new ultra high by-pass engines (it was designed for a 60s turbot jet). Sure they can fudge it into place … with the previous model they had to flatten the bottom of the nacelle, this time they had to raise the nacelle and had all the collateral issues to deal with. Or they could have up shortening links into the landing gear … a route they knew about and didn't go down.

another day in paradise, or is paradise one day closer ?

 

[Alistair_Heaton]

i agree and have been putting that view forward since 7 threads ago.

But also refusing to put in a EICAS system for information transfer to the pilots is also a major issue.