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

 

[3DDave]

The AoA sensor on the Lion Air plane was malfunctioning in the maintenance hanger, but maintenance workers did not perform any post maintenance check to see if they had done the work correctly. Subsequently, with the benefit of hindsight, it was clear there was a difference in readings during takeoff, at which point it was too late.

On-ground conditions are not suitable during taxi to diagnose a problem. There is no BIT that can detect it without also giving an unacceptable number of false positives. Full hard braking of a fully fueled and loaded jet liner has a non-zero chance to end in a run-off fireball crash.

The "fix" would see pilots on step ladders moving the vanes manually with a precision level attached or some vernier marking; of course if the Lion Air repair team had bothered to do that most of this conversation would not be happening.

 

[Alistair_Heaton]

There is usually a scale on the metal next to the vane with a pointer which is crude. But would have picked up the colossal discrepancy that the lion air had. But you would have had to have access to the AoA reading in the cockpit which was a 200k software upgrade per aircraft which only one customer paid for. Everyone is now getting it for free. I don't have a clue if the AoA mismatch flag which wasn't working would have saved the day. I suspect not because it would have only been activated when the WOW indicated airborne. There is zero possibility to get pilots checking calibration pre flight that is a technician function. 15 years ago I did hold several maint approvals for doing checks and even changing tyres but 10 years ago the regulators banded it. We have 4 pilots that were licensed B1's and even they are not allowed to fix the plane if anything goes wrong in a outstation. They can do more than the rest of us with written instruction from the CAMO but its extremely limited and seldom used. Everytime they fix something a report is sent to the CAA. If they do work in the hanger then a report also needs to be filled out and proof that the working time has been added to the FTL records shown.

There is three bite tests and checks of the sensors that I can see so far for the A220 before the wheels leave the ground from power on. If the power stays on for the day its 3 on the first flight and then one per flight.

The first is on power up which are for things speaking to each other and general is it working.

Second is after the IRS come online which can take 20 mins after power up depending how far north/south you are. We don't need to know what's happening thankfully the EICAS will tell us what's wrong and if something is showing red we phone the technicians.

Third is at 60 knots every takeoff. And it will tell you to abort the departure. If something is a go item it won't tell you about the failure until 400ft. If you need to stop it will set the bells and whistles master caution system off and you abort. There is no interpretation required or thinking. If alarms go off you hit the brakes the plane takes the power off if you haven't already. If you pull the power levers back it automatically triggers the autobrakes for emergency deceleration. There is something about variable breaking power depending on the speed you abort at and the runway left but I haven't done brakes yet.

I wouldn't disagree with the statement that full hard braking won't result in a runway excursion. A lot of runways in the 1st world have deceleration pits at the ends to increase the effective runway available for takeoff. But they aren't strong enough to taxi on. If you go in them the plane sinks. Its a fudge to allow higher weights for departure but not have to pay for runway that never gets a tyre on it 99.99% of the time. They are though extremely effective when used. Not much damage to the aircraft just a bit of gravel rash and a gear inspection and it will be flying again usually the same day.

There are basically two aborts. Low energy under 80knts which you stop for anything caution or warning.

Second is high energy abort between 80knts and V1. The performance is calculated that you will remain on the ASDA (accelerated stop distance available) but there may be damage to the aircraft tyres blown, fire service needing to deal with brake fires and the aircraft requiring maint inspection. Just before V1 abort on a +100 ton aircraft is pretty major to be honest. And can damage the runway. You only stop for certain failures.

Between V1 and Vr you don't have enough ASDA in front of you to stop, but you do have enough to accelerate with an engine failed and take off before the end. Which may mean that the wheels only leave the ground on the piano keys at the end of the runway. Things are further complicated with the use of de rated departures and flex where the engine power is set for the runway length and conditions.

This rejection stuff comes up every day we are in the sim. There is at least 1 go situation and 1 abort situation. And its pretty horrible on a none EICAS machine. You have the attention getting going off then is it a yellow or red then PM should call it. You should remember what the last speed call was. Then decide if to go or not. All while 9000 shaft horse power is throwing a 22k to 29.5k kg aircraft down the runway in the case of a Q400. At 22k kg we are off the ground at 130 mph inside 10 seconds. Quite looking forward to this not having to think stuff with the EICAS.

 

[Alistair_Heaton]

There are noises that Boeing will be doing a FAA recertification flights before the end of June.

There is nothing from EASA or the other regulators. With the quarantine rules they would be all hit with two weeks coming back.

So if they approve it you might see a 737 max in the air by October with pax on it on USA internal flights if the FAA release it. They still have to do the training side of things.

 

[Alistair_Heaton]

This is for interest. I didn't see the point of giving it a thread to itself. Its a 737-800 but it could happen to any type. Just thought it was a nice report and for once the pilots didn't screw up.

FOD is always a worry but not a lot you can do about it.

The departure airport is always one that causes increased thought. Not quiet as bad as Varga but still your surrounded by water and lengthy transits if you don't want to go straight back.

Lovely place to operate into when the weather is nice when its orrible which is most of the time its requires you to be very switched on while feet wet.

http://www.rnsa.is/media/4688/final-report-ei-fhd-on-bikf-june-16th-2018.pdf

 

[dik]

Some more news...

https://www.design-engineering.com/...boeing-1004035046/?oly_enc_id=4468G4022034A5X

Dik

 

[IRstuff]

The report makes it sound almost leisurely; seems like they had ample time to do all the right things. Had the FOD damage been worse, the outcome could have been very different.

TTFN (ta ta for now)
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[Alistair_Heaton]

Detailed inspection of the aircraft revealed the following damage:
 LH inboard main wheel tire burst
 Four (4) broken spoiler cables
 Downlock sensor system wire cut
 Air-ground sensor system wire cut
 Fuel temperature system wire cut
 Two (2) landing retract/extract hydraulic line broken
 Four (4) tubes to heat exchanger broken
 Three (3) tubes for brake/shimmy damper broken
 One (1) tube for engine driven pump pressure supply dented
 One (1) tube from shut off valve broken
 Flow regulator valve missing from LH wheel well for hydraulic system A
 Aileron pulley broken in wheel well
 Three (3) spoiler pulleys broken
 Fixed trailing edge panel punctured
 Support brackets for hydraulic pipes including fairleads damaged
 Dents on both main and aft inboard flaps
 Dent on LH horizontal stabilize


That's quiet a hefty damage bill to be honest And also one of the primary hydraulics circuits gone. Turn spoilers/lift dump gone. Alternate gear extension pretty horrible day at work in central Europe never mind hundreds of miles of hostile ocean to go over or return to a very short runway.
I was wondering why they didn't go for Prestwick but then if you have managed to get from Iceland to UK without any issues an extra 15 -20 mins in the cruise to go to BHX doesn't make any difference compared to going to Prestwick without any company tech support.

 

[IRstuff]

The report indicates the crew considered and rejected Prestwick in favor of Birmingham, presumably for both better ground support and a longer runway. Prestwick's runway was just shy of their desired 3-km length, while Birmingham is at 3.66 km

TTFN (ta ta for now)
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[Alistair_Heaton]

If you where going for length and safety you would go for Manchester with twin 3km runways 3048 and 3050

BHX is 3052 meters single runway.

PIK is 2986m

Campbell town also used have a 3km runway which was a space shuttle diversion airport along with PIK.

Plausible excuse that nobody cares about would be what i would term it.

I do know someone that went past MAN and BHX and landed in Stansted after an engine failure. When asked why he went there he answer that's where my car is parked the bird is 180 mins ETOPs certified and we had only had the engine shut down for 20 mins, another 20 mins to get to my car shouldn't be a problem... The AIBB bloke just smiled and said right I don't think we will bother discussing that point in the report.

 

[IRstuff]

They traded also the possibility of tying a busy runway if the plane became disabled or seriously damaged on landing, so I expect that might have played into not picking Manchester

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[Alistair_Heaton]

I am maybe a bit biased about going anywhere near BHX due to having worked in there for 2 years. Both ends of the runway can give sporty conditions in even moderate winds. Plus the runway is not exactly flat.

This video is doing the rounds of pilots just now.

Totally mucked up the de-crabbing and flare and put full wrong direction alerions deflection in after touch down. Plus they look as if they slammed it into beta range. There wont be a report on this one though.

https://youtu.be/H5mnCEMzV-0

 

[IRstuff]

Like I said, leisurely, so they had time to get weather reports, etc., to flesh out their decision. Then, again, maybe they thought it fitting that if they were to disable a runway, that it be BHX's

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[Alistair_Heaton]

which is another reason to go to MAN they have two fire stations one for each runway and can continue operations with one team at an incident and one runway down up to 747 or A380 size inbounds.

The first decision not to go back would have been done relatively quickly before high level climb. The rest they had plenty of time to do.

It will centre round maint bases and where there is a spare aircraft for the punters. BHX is actually very busy with plenty of heavy hardware in and out, about the same as Manchester.

They used to have quiet a few planes going through there but closed it in 2017.

You normally you try not to go to crash at your own company's operations. You go somewhere else. Liverpool was getting well pissed off with a previous company of mine because we always went there if there was any problems going to MAN,BHX or LBA. There was a good hanger there to fix things as well. And the bus ride wasn't that long to get the pax to destination. So there runway was shut multiple times for hours with usually hydraulic issues and then needed towed off and the runway inspected and fixed if a tyre had blown.


As I said plausible excuse that nobody cares about.

 

[waross]

I do know someone that went past MAN and BHX and landed in Stansted after an engine failure. When asked why he went there he answer that's where my car is parked

That reminds me of some trips from Vancouver to the Okanagan valley many years ago.
The flight was to Penticton and Kelowna. (A Kelowna ticket was $0.50 more due to an airport tax.)
Whichever city the flight landed at, passengers would be bused to the other city.
When the flight left Vancouver the pilots did not know their destination.
When they got within radio range of Penticton and Kelowna they would ask ATC;
"Where is the bus parked today?"
They would then divert either North or South and land at the city where the bus was, and announce to the passengers what the destination would be. This was about 15 or 20 minutes before touch-down.
I lived between the two cities.
Once I learned the system I always bought a ticket to Penticton and saved the $0.50.
There was no check of ticket destination.
I would get on the bus with my carry-on and the driver would let me off as we passed within walking distance of home.

"When asked why he went there he answer that's where my car is parked"
"Where is the bus parked today?"

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

 

[LittleInch]

I had a quick look on GE.

Birmingham tarmac is 3000m, but piano keys to keys is only 2300 whets stn or PIK is 2759. Runway is 15/33 which is quite strange for the UK where many are much more east west so maybe that was included in their assessment. Definitely more room to run off the end a bit.

It's still rather frightening that the wheel bays were so vulnerable though. Punctured tyres aren't that rare. And all from a piece of metal as long as your hand.

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

 

[Alistair_Heaton]

It was FOD that got Concorde in the end. The BA ones had a tyre stripper on the wheels but AF never fitted it. There was multiple other issues with that flight but the tyre getting taken out was the start of the other issues being able to come to the fore.

Piano keys to piano doesn't really give the full picture there are multiple rules about what you can and can't use as your distances for landing and take-off and they can be significantly different depending on the objects off either end of the runway. Touch down marker to end of the runway is a good enough approximation.

But I would be surprised if PIK is worse off than BHX. Most of PIK's life it has been a NATO heavy Nuke bomber designated runway. It is utterly colossal and there is nothing much round it only thing that will beat it are the eastern Germany runways but they are all concrete slab. Its also one of these microclimate airports where the local wx system is usually much better than the rest of the UK. BHX is a pain in the the bum sporty approach slippery in the last third up and down wavy runway, As the ATP tried to do you have to try and hit the top of the first hill other wise you end up floating down the back side. Anyway Just because I would think twice about taking a sick aircraft their is only my personal opinion and mostly dictated by having over 1000 landings there. I have similar at MAN and apart from the pissing rain it would be my preferred option.

Tyres are never really give the respect they are due to be honest in my experience. Each one is a bomb sitting on your aircraft. They are fitted with thermal fuses and the like but they are expected to sit in sub zero temps for hours then get smashed into the deck and spun up to 110-150 knts in fractions of a second then have to transfer colossal amounts of energy through them. IF they let go there is colossal energy stored in them. I tend to not go near them after landing and when I have to approach them do so in the alleged safe zone.

And a complete explosion of a tyre like that is relatively rare thankfully, I have never had one. And only one mate has had something even remotely similar. It was the youtube video of the Q400 tyre deflating on takeoff in AMS and they eventually landed back in the UK i think. Thankfully that was a none event apart from the media hype.

Honestly I wouldn't get to into why they went to BHX, they will have been discussing it with ops and they will have given them a preferred airport to get to. That will have included the availability of another crew and aircraft to move the pax onwards, engineering support, ground handling, departure slots available (which is a pain in the bum at MAN at peak times). If the aircraft has been running ok for the previous 2 hours feet wet with both engines still working and you have multiple options in front of you/around you its really not a big deal. Personally I would have preferred PIK, Man or East Midlands at 2893 meters but thats just me based on personal experience of all the UK airports flying regional turboprop which this crew more than likely didn't have. I would be in the same situation in there native countries.

 

[Alistair_Heaton]

Just been reading about the FAA stuff must admit I don't understand or know about the USA legal process with this. From what I can see is there is a major push from both sides to either maintain current situation with the FAA and Boeing or dial back the clock 30 years.

To be honest I can't see much difference between the current investigations and the Challenger post accident process and NASA. A lot of people move jobs or retire and fade out of the picture, there is noise and people are a bit more cautious for a period and then a new genration come along who have vague memory's of the period and then it goes back to the way it was.

Only thing different is the international aspect to to this because although big the USA market is only a part of the bigger sales picture. So if the USA doesn't fix it properly the planes won't be getting a world wide certification and they will have to do it properly anyway, which will mean the aircraft will be built differently anyway. We shall see what happens in that regard i can't see things going back to multi national certification of new types until there has been 2-3 new aircraft go through the system which will occur for the 737 MAX to get it flying again with no problems. And as Boeing doesn't have anything even remotely on the books for future development that will take some time.

Must admit hearing some of the political types spout off you do wonder if they realise that it doesn't matter what the home grown voters think when it comes to the FAA if the rest of the world doesn't buy it, then Boeing is going to have to walk the walk anyway or its a dead duck.

The issue of grandfather rights and design auditing for human factors though is an international issue and needs to be applied globally. And more than a few pilots think its about time the airbus FBW system is revisited on the human factors front, and i am one of them. The PIA thread on this forum is case in point for the reasons why.

 

[LittleInch]

BHX looks like an interesting runway alright....

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

 

[IRstuff]

There was talk, a while ago, to have airplane wheel motors to spin up the wheels during landing to minimize that rubber-meeting-the-runway event

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[moon161]

^I asked my dad about that in the 70's, and he said they'd looked at that in the 40's. Nothing that would justify the weight penalty, maybe that'll changed someday.