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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
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Ethiopean Boeing crash

This as a comment on the FT.com this morning from someone who sounds like he knows something about the issue. One wonders if the US would have acted as fast as the Chinese if it had been an Airbus

Could Boeing’s continued attempts to keep up with Airbus may have come back to bite them here?
- the original 737 was certified in 1967. Boeing has made extensive “hacks” over the years to try to avoid all new versions aircraft having to be recertified as completely new designs (£££). For example, the size of the main passenger doors would never be allowed in a clean sheet design (see also: 747-8 zone A forward of door 1, with only one escape route)
- the 737 Max 8/9 have far more powerful engines than the 1960s designed ever imagined, and they are further forward on the airframe
- during a go-around (aborted landing) a high power setting could cause a significant pitch up movement which the natural pitch stability of the horizontal stabiliser would struggle to counter (as the horizontal stab is the same size as the 1967 version)
- this high pitch and resulting high “angle of attack” could lead to a stall
- Boeing therefore designed a “MCAS” system to automatically roll on forward trim during high AoA situations i.e. forcing the nose down
- this system operates independently of pilot control even with the autopilot off
- Boeing didn’t train pilots about this system, because most legacy 737 operators hate having to train pilots again when buying new versions of the aircraft (indeed, Boeing market every new 737 as “just another 737.”)
- the system can activate with only one faulty AoA indication - a broken probe, for example
- recovery from a MCAS induced pitch down is possible but needs careful handling, disabling the trim and so on. Tricky if you haven’t been trained, and know nothing about the system that could be causing it.
In a nutshell Boeing seem to have grafted Airbus-style flight envelope protection onto a 1960s design and haven’t told anyone about it so nobody knows how to handle it when it goes wrong. 3 x FL1 2 manual + 1 auto no real problems
FL2 S 08 reg 100k no problems
FL2 S 10 reg Gearbox, clutch, throttle body, drive shaft, steering reservoir
FL2 GS 60 reg xfer box, diff and wheel bearings
FL2 GS 11 reg gearbox ,hesitation, exhaust sensors, wiper stalk,
FL2 XS 14 reg SD4 Auto , door lock problem @ 29k

Post #368204 11th Mar 2019 10:56 am
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Dartman the one



Member Since: 04 Apr 2013
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England 2012 Freelander 2 SD4 HSE Auto Orkney Grey

Interesting Dorset, however both these accidents have happened in very warm climates, both aircraft were owned by third world airlines with good safety records. The BBC news this morning stated the aircraft have two factories building them Seattle and China, the origin of either aircraft has not been stated.
Boeing have had some dodgy history with engines, the 707 had a habit of dropping them off the wings in the early days and the 747 carried a 5th engine again in the early days due to frequent engine failures, then there was the Dreamliner problems with batteries my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey

Post #368209 11th Mar 2019 12:05 pm
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pab



Member Since: 28 Aug 2012
Location: North Pennines
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The only actual information we have at this time is that provided by FlightRadar 24 relating to ground speed, vertical speed and altitude (https://www.flightradar24.com/blog/flightr...light-302/).

Assuming this is correct it shows an erratic vertical speed, and towards the end of the data a rate of climb which seems unlikely to be intentional given the circumstances. At least one press report claims the pilots had reported a problem and were returning to land - if that were indeed the case then a max-rate climb would not be expected.

Again, assuming the data is correct. Reports now indicate that the black boxes have been found, so hopefully more information will be available soon.

Post #368213 11th Mar 2019 1:00 pm
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Steve D



Member Since: 19 Jan 2013
Location: Essexshire
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I saw on the news that there are none of these planes in the UK yet although RyanAir and one other budget carrier are getting some. Past: FL2 TD4 HSE Auto
Present: Evoque SD4 Dynamic Lux Auto

Post #368261 12th Mar 2019 8:54 am
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dorsetfreelander



Member Since: 20 Jul 2013
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Everywhere except the US is grounding these planes. I bet that if it was an Airbus that the US FAA would act differently. "America First" etc definite conflict of interest here. 3 x FL1 2 manual + 1 auto no real problems
FL2 S 08 reg 100k no problems
FL2 S 10 reg Gearbox, clutch, throttle body, drive shaft, steering reservoir
FL2 GS 60 reg xfer box, diff and wheel bearings
FL2 GS 11 reg gearbox ,hesitation, exhaust sensors, wiper stalk,
FL2 XS 14 reg SD4 Auto , door lock problem @ 29k

Post #368264 12th Mar 2019 10:29 am
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pab



Member Since: 28 Aug 2012
Location: North Pennines
Posts: 1943

United Kingdom 2009 Freelander 2 TD4 XS Manual Lago Grey

Two crashes of a brand new aircraft, both apparently due to issues with attitude control, would certainly seem to give cause for concern!

With the usual provisos about accuracy of the data, etc, it is interesting to compare the FlightRadar 24 data from the Ethiopian flight (link above) with that for the Lion Air flight (https://www.flightradar24.com/blog/flightr...ght-jt610/) - there are quite notable similarities. Both appear to struggle with attitude control before ending in a sudden and very steep climb. In the Lion Air data one can then see the subsequent stall and uncontrolled descent into terrain. In the Ethiopian data this descent data is not present, but given the way the flight ended there was clearly a similarly uncontrolled descent.

What is perhaps particularly concerning is that the MCAS system can supposedly be over-ridden using the elevator trim control, and that following the Lion Air crash airlines and pilots should have been briefed on what to do in case of issues with MCAS, and yet the Ethiopian aircraft still crashed.

The 737 MAX series is Boeing's best selling aircraft, with more that 5000 total orders, so Boeing need to get on top of this very quickly!

Post #368278 12th Mar 2019 11:12 am
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dorsetfreelander



Member Since: 20 Jul 2013
Location: Dorset
Posts: 3489

United Kingdom 2014 Freelander 2 SD4 XS Auto Loire Blue

Could this be Boeing's Volkswagen Dieselgate moment? 3 x FL1 2 manual + 1 auto no real problems
FL2 S 08 reg 100k no problems
FL2 S 10 reg Gearbox, clutch, throttle body, drive shaft, steering reservoir
FL2 GS 60 reg xfer box, diff and wheel bearings
FL2 GS 11 reg gearbox ,hesitation, exhaust sensors, wiper stalk,
FL2 XS 14 reg SD4 Auto , door lock problem @ 29k

Post #368279 12th Mar 2019 11:15 am
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IanMetro



Member Since: 11 Sep 2017
Location: Somerset BS21
Posts: 929

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The Federal Aviation Administration has told Boeing it will order the company by next month to institute safety-related software enhancements to its 737 Max 8 planes, Boeing said late Monday

https://www.cbsnews.com/news/boeing-737-ma...rade-mcas/

It seems that Boeing have been working on software update since the last crash.

From what I have read elsewhere, it seems that the MAX 8 version of the 737 resulted in changes to its engine position that effects both static and dynamic centres of gravity and thrust.
The anti stall software was changed, but had been know to malfunction.

The system automatically points the plane's nose down if sensors indicate the plane could be in danger of losing lift, or stalling. Sensors on the plane operated by Indonesia's Lion Air gave out faulty readings on its last four flights.

I think the 'work around' around mainly was trying to find the switch to turn it off once the pilot had realised he had no control and was heading towards the ground.

The risk surely was great enough to ground all planes soon after the first crash, until fix installed and tested.

Just looked again and most countries think that as well.

The UK's Civil Aviation Authority (CAA) has banned the Boeing 737 MAX from operating in or over UK airspace "as a precautionary measure".

https://www.bbc.co.uk/news/world-asia-47536502 FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 38k+ miles)

Post #368300 12th Mar 2019 6:35 pm
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IanMetro



Member Since: 11 Sep 2017
Location: Somerset BS21
Posts: 929

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Finally

Boeing has grounded its entire global fleet of 737 Max aircraft after investigators uncovered new evidence at the scene of the fatal Ethiopian Airlines crash.

https://www.bbc.co.uk/news/business-47562727 FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 38k+ miles)

Post #368377 14th Mar 2019 12:13 am
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