Boeing 737 Max8 Aircraft Crashes and Investigations [Part 5] 19

[Sparweb]

This is the continuation from:

thread815-445840
thread815-450258
thread815-452000
thread815-454283

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

Indonesian National Transportation Safety Committee preliminary report

A Boeing 737 Technical Site

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

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[VEBill]

I have a nightmare vision of 400 brand new 737 Max being chopped up for scrap.

 

[waross]

Don't forget the 387 MAX that have already been delivered.
At list price and expenses and penalties the gross cost at list price could exceed a trillion dollars. (Less salvage).
It is way past time for the board of directors and management to stop telling engineering what to do and start asking;
"What can we do."
A suggested course of action to take a lemon and make lemonade and save the day.
Put the Max on the back burner.
Concentrate on upgrading the existing fleet of NGs with Leap engines.
One solution may be extended landing gear and under-wing mounted engines. (And new pickle forks)
Apply the solution to the grounded MAX-8s.
There could be a lot of business converting newer NGs.
With over a year lost and further lead time until MAX production resumes, the MAXs will replace older NGs as they are retired.
Sure this may not be the best solution but it may be better than where they are now.

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

 

[IRstuff]

I'm just saying that Airbus has had silly problems as well, notably:

https://en.wikipedia.org/wiki/Air_France_Flight_447

wherein a less-than one kilobuck sensor took down an A330 and 288 souls. Given that this was not the first instance of this type of sensor's vulnerability to icing, neither FAA nor any other agency demanded redundancy. Of course, in this particular case, there was the argument that the flight crew responded poorly to the situation, but there are claims that the cockpit displays were less than informative.

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]

you can't fit leaps to a NG you hit the same issue with ground clearance.

If you could they would have done it.

Any change to the landing gear is years of work and more than likely not possible due lack of room. Be quicker doing a fresh sheet design.

Fitting a 3rd AoA sensor would be quicker.

I suspect they are looking at putting spoilers on the base of the engines which pop out when the WOW switch says airborne. Or your in certain speed ranges. Or autopilot is out. It will give a fuel hit but if it sorts the dodgy aerodynamics out then so be it.

The whole world wide aviation industry can't afford for those airframes to be scrapped or for that matter 50% of the world production of single isle aircraft to evaporate for the next couple of years.

AF477 was purely incompetent flight crew, from the point that the skipper decided that it was acceptable to leave the cockpit while the plane flew through the ITZC through to the pilots in the cockpit pulling back on the stick all the way to their deaths and those of the PAX. First world crew, legacy airline, everything documented by Airbus. yes there was a snag in the design but the aircraft was flyable. In fact if the pilots had taken their hands off the controls they would likely have survived.

 

[davefitz]

A possible way out for the airlines and FAA is to certify the Max with 3 AoA sensors, and let the airlines install the add'l sensors w/o Boeing. This avoids the Boeing legal issue re: it would be asked why they did not use 3 initially, and if they agree then they may be agreeing to negligence. Negligence = infinite damages = bankruptcy, unless you own 2 appeals court judges. If Airbus has a proven /patented redundant sensor system, it sounds like an opportunity for airbus, but then who owns the liability?.

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

 

[Alistair_Heaton]

Airlines can't add stuff like that, it has to go through the type approval holder. They can't even add a USB charging port in the cockpit without Boeing signing it off. Which Boeing will charge for, several 10 000's of $. Its called a Supplementary Type Certificate.

Sticking a extra AoA sensor on the aircraft is easier said than done, You have the positioning of it which will require a fair amount of thought to give clean undisturbed air over it. Then you have the to change the system architecture to be able to use it. Then you have to test it to prove its fit for the job and the software is working properly. Its a colossal job and extremely expensive both in $ and in time. Although now for Boeing we are getting near the point that if they had started it on day one of the grounding it would now being getting close to it being able to go through in another 6-9 months. Airlines just don't hold the skill set to be able to do it in house. Boeing can't even do it in house they will have to farm the system architecture changes out to Rockwell who they own anyway.

There are several 3 AoA feed aircraft out there not just airbus. They use physical AoA sensors and also some use pseudo calculated AoA from the laser gyro's.

The way the system is setup there is only one entity who is liable for the aircraft design. Everything gets channelled through that entity and they have full veto on allowing modifications, its a reasonable income stream for OEM's. A new certified coffee machine including STC for hard wiring into the galley bus is over 25000$ each. The none certified version of exactly the same machine will cost you less than 250 $.

Another example of this is a fuel pump for a PA38. The certified part with all the certs and serial number is 900 $ you can pick up exactly the same unit minus the data plate from any chevy parts supplier for 35$. Quite a few flying school owners are quiet good with riveting and just swap the plate to the new unit.

Float balls in the water system cost 190$ each. Or you get a bit of sand paper and a yellow dot squash ball and sand the markings off for 3$. That one was discovered when someone was visiting the OEM and saw an apprentice at a bench busy with a pile of squash balls and sandpaper and a load of zip lock bags with serial numbers on them. Sales of float balls have reduced dramatically since and as they don't have serial numbers marked on them there isn't a lot the OEM can do about it.

 

[verymadmac]

Boeing has no say in STC approvals, one can merrily carve airframes up for major reconfigurations with no OEM support, its just often cheaper to get support from the OEM but its not required (read give them a big wad of cash for access to design data, because its cheaper than reverse engineering).

However, if you accidentally tell Boeing that you have converted several to freighters with an STC that has Boeing support, they will still want 50K per airframe to keep supplying tech pub support. There isn't any reason for the charge it was just that they could.

 

[Alistair_Heaton]

I can only say my experience of STC is in EASA land and all of them were pre EASA under JAR. It was virtually impossible without OEM involvement and that was for relatively simple stuff with just power connections for a sub 10 ton turboprop. We are talking a LCD screen and mp3 player to do safety briefs.

There are more than a few FAA STC's which have to be ripped out for an aircraft to go on EASA member reg.

The coffee maker above is available on a FAA STC at the bargain price of 10 000$ if your flying N reg. Daft thing is people pay that price so they can have filter coffee brewed at 8k cabin alt at 95deg or what ever the temp is for "perfect coffee" but is impossible at 8k due to a lower boiling point of water unless you have a fancy coffee maker. The coffee costs a fortune as well because its a special mix to account for the change in taste at higher altitudes.

I can't see how you can't tell the OEM if you rip out the cabin and put in freight floor and lashing points. For a start you will need a smoke detector in the cabin area which will mean a change in wiring which will need an update to the aircraft manuals and checklists including QRH which will all need to be approved by the OEM. Otherwise your MOM will be out and also your AFM and AOM. No part 145 company would touch it even for a daily service check.

But I have pretty much zero clue how these things work in FAA land.

But I think we can agree though that there is zero chance a group of airlines are going to get together and sort out Boeings stupidity by getting a 3rd AoA setup certified when they haven't even taken delivery of the aircraft.

 

[Sparweb]

Those of us who design, certify and install STC design changes often do just fine without the OEM's support. That includes providing supplementary maintenance, operation, and flight manuals. I've written many such documents.

The impression (that we get in North America, at least) that EASA does the bidding of Airbus only emphasizes the other impression (held by European and NA operators alike) that EASA is there to enforce the OEM privileges, not just their rights. Ask yourself why Wideroe has such a close relationship with US and Canadian airframe leasing and modification companies.

But your last point, about airlines sorting out the AOA configuration, is true - even if they could add the sensor, how could they force the software to accept the data input? That's a deep level of software redevelopment, and only the owner of the software (Boeing) is in control of that.

I've actually spent some time trying to think of possible 3rd party STC's that could be installed to ameliorate the 737 Max situation. So far nothing practical. One option would be a device to disrupt the airflow over the engine cowling - enough to eliminate the pitch-up trend at high angle of attack. This would negate the fuel efficiency of the aircraft, of course. It would also require a dicey flight-test program.

http://www.sparweb.ca

 

[Alistair_Heaton]

Norway hasn't issued a STC since 2005. they are all EASA. Same rules as anyone else.

Its not just Wideroe that's sends it dashs across the pond to get C checks and mods done.

My company does it as well. Its not cheaper on paper than using EU located facilities. But it is when you take into account that the aircraft can usually start flying pax 45 mins after it landed on return and you don't have to spend months chasing snags down. So it more to do with the quality of work than anything else.

EASA provides the rules and a hint at a compliance method. BAe system are a pain in the arse for getting anything approved and since all the manuals have gone electronic on there portal thingy you can't even edit them or stick 3rd party paperwork in the back of them. So to get anything added to the legally required manuals you have to tell them about it and stump up a 5 figure sum for them to copy and paste the documents into the aircraft manuals. I suspect the ease which you get stuff through is more to do with Bombardier information flow policy than anything else. You already have the required data from previous STC's so no need to get it again. BAe will only give data for an individual airframe and slap headers on it stipulating that its not valid for any other airframe.

 

[VEBill]

"...a device to disrupt the airflow over the engine cowling..."

I saw a tidbit about NASCAR adding hinged flaps to the top sides of their race cars. When the cars skid sideways at 200 mph, the flaps inherently react to the resultant aerodynamic lift, opening, instantly killing the aerodynamic lift. So the car can skid sideways endlessly without getting airborne and rolling into a ball. Easy solution to a complex problem.

A link in case it helps.

If the 737 Max engine cowlings are producing unwanted lift in certain circumstances, then perhaps the same sort of concept could be applied here.

Find an area on the cowling with the best air pressure 'signal' (correlated with the issue), and add a purely mechanical system to pop open flaps to disrupt the lift, automatically and inherently. The lift would pull the flap open, against calibrated springs, neatly disrupting the lift.

Yes, obviously dampers would be needed to avoid noisy oscillation.

...Yes, yes, yes, I know. It "can't possibly work." It would cost "a trillion dollars" and "take decades to certify."

In fact, a clever design team might invent a simple drop-in panel assembly to achieve this sort of solution.

Just an idea. Dime a dozen here.

 

[moon161]

^ I was thinking along those lines too. It might be that boeing confined themselves to 'the almost the same as <but with this minor change>' design path to keep certification as a 737-whatever. It could even be a passive element like a leading edge slat can be.

 

[Alistair_Heaton]

I suspect your spoller idea wouldnt be that difficult to get certified if it was purely analogue mechanical or hydraulic and the fail safe was deployed.

Certainly a helluva lot easier than getting the aircraft to fbw regs.

 

[moon161]

I think there has to be a synchronous deploy/retract built in. There have been crashes and near misses related to asymmetric high lift devices. It could be dead simple like a blown door, flap or something. It could be activated by differential pressure like a stall horn. The trick is to induce a separation instead of energizing the boundary layer like vortex generators or blown flaps.

A passive unactuated flap that stuck up opposing the airflow would deploy at high AOA and then not close until the AOA settled down.

 

[moon161]

This flap could even be normally deployed by a spring and only forced closed by air flowing at low/normal AOA. Paint it bright red or yellow on the underside so it's easily inspectable.

VeBill, Sparweb, we're gonna split a billion dollars ;-)

 

[Lou Scannon]

Now it just needs a name... how about mechanical crash avoidance system?
MCAS, has a nice ring to it, or?

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[Alistair_Heaton]

There is already an automatic slat deployment system out there that does the same thing.

Mind you we are making a huge assumption here that the lift from the cowls is the only thing that's stopping recertification. I doubt very much it is a singular issue with the MAX stopping recertification.

The autopilot failing to disconnect as spotted in this forum is definitely on the list but hasn't been mentioned in any media release.

 

[Sparweb]

Mind you we are making a huge assumption here

Jeez AH, this is an internet forum. This is fun!

Thanks for the NASCAR links VEBill, I hadn't make the connection.
Do you think if you, me, and Richard Petty brought this to a FAA certification office, we'd have a chance? What's the closest ACO to Charlotte NC?

http://www.sparweb.ca

 

[Spartan5]

I saw a tidbit about NASCAR adding hinged flaps to the top sides of their race cars. When the cars skid sideways at 200 mph, the flaps inherently react to the resultant aerodynamic lift, opening, instantly killing the aerodynamic lift. So the car can skid sideways endlessly without getting airborne and rolling into a ball. Easy solution to a complex problem.

These flaps?

 

[VEBill]

We'll let Mr Petty drive...