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Boeing 737 Max 8


Paul Marsh
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Posted by alan p on 10/03/2019 16:02:41:

tragic for the families concerned.

Concorde one crash and scrapped

Boeing 737 lost count still flying!!!

Concorde wasn't scrapped because of the crash, but because Air France decided to pull it out of service and the manufacturer wouldn't then continue to certify it for one airline. The 737 Max crashes are concerning.

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Probably the Lead Investigator currently investigating the Air Lion crash has another crash to solve, as the two incidents are similiar, and as happened before, maybe either crash might give a picture of both.

I will take a couple of years before the full report will come out, so, at the moment, it's speculation, although some recommendations on an interim report has been released regarding addressing wrong cockpit readings.

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Also some speculation relating to pitot tubes not working correctly and feeding into the anti-stall system, if I recall right?

"Boeing 737 lost count still flying!!!"

Original 737 is now 51 years old, so the type as a whole has a few flight hours.

The 737 Max is not long in service, 2017 according to wiki, and 2 accidents.

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A friend who was at the time in the RAF was sent to a Canbera crash site as part of the recovery team. On arrival at the field there was nothing obvious until the farmer pointed them to a spot with three holes in the ground joined together by a thin trench and a few small bits of metal scattered about . Crew had abandoned the aircraft after the controls had jammed and it had gone straight in.

After two days digging they were down to the cockpit remains and found the culprit,a loose nut was jammed at the base of the control column.

Edited By J D 8 on 11/03/2019 16:06:42

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It would seam that much like we do with computer radios Boeing used an electronic fix to sort an aerodynamic problem.

In the past if there was such a problem a mechanical fix had to be found as with the Sunderland flying boat when the cog was aft of where predicted.

Adding nose weight like the Hurricane was not an option on such large aircraft. Moving the wing back would have needed much reworking of the hull. The quickest option was to sweep the wings back a bit but no changes to the engine thrust lines were made so they angle out a bit. Flew just fine.

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Posted by Nigel R on 12/03/2019 10:24:02:

Which aerodynamic problem does the electronic fix sort out?

The elevator trim being driven to its maximum down deflection could be considered to be an aerodynamic problem if the aircraft is in an otherwise stable condition. The software fix is supposed to be designed to limit the deflection throws I believe.

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MaL - If I understand and remember right, that's a speculation on the cause of the Lion Air incident, the postulation being that the electronic stall avoidance system (introduced on the MAX) had malfunctioned and driven the tab to induce full down trim. I'd imagine if that is found to be the case a software update - and possibly hardware or sensor update - for the stall system will be made very, very quickly. But. I'm not sure we can call that an aerodynamic problem with the aircraft?

JD8 was there a specific problem with the 737 MAX you were thinking about, that an electronic fix of some sort had been made to overcome, relevant to the latest incident?

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When the Airbus family of twin jets was launched they had several total losses and one or two very close calls, mainly due to incomplete or rushed pilot training.

An 8,000 hour senior captain would not willingly allow a jet under his command to crash if he knew what the fix was.

Take the Air France A330 out of Rio I think, that stalled into the South Atlantic. Because they weren't trained thoroughly in modern crew concepts, and were brainwashed into believing that Airbuses cannot stall, they didn't know what the fix was.

Better training would have saved them all, as was proved by an ex- BA colleague of mine who suffered exactly the same failure of airspeed inputs on an A330 from Manila to Hong Kong many years ago. Power setting and attitude information will always give a certain speed in all phases of flight so get back to basics and the plane will still fly without any of the computers. The Quantas A380 which had a catastrophic engine failure out of Singapore that took out 65% of almost everything, quite rightly initially ignored the hundreds of lines of emergency checklists and found out very quickly what he could still do or not do with the plane: turn right, turn left, go up, go down....sorted! Now read the checklist!!

It's sad that Boeing has followed Airbus down the "computer will fix it" road at the expense of basic pilot skills, for that seems to be the cause of this tragedy.

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As we have no idea what caused the Ethiopian crash, it's all speculation.

In fact we don't know 100% what caused the Lion Air crash, although the preliminary report is out there.

There is no evidence that the software "went wrong". The preliminary report of the Lion Air incident suggests a system design issue coupled with poor pilot training - a reliance on single sensor input, and allowing that input to precipitate a complete override of pilot input. The anti stall system as a whole could be disconnected - and the report documents the previous flight doing this on the (Lion Air) aircraft that crashed, and continuing to their destination without further incident - although relying on the pilot to diagnose the correct system and disconnection procedure whilst simultaneously dealing with an emergency situation might also be a bit of a system design problem too. The report also points out the previous flight crew failed to record any of that in the log which is a bit of a bad sign as to how well the pilots are holding up and performing, so perhaps the airlines are flogging their pilots too hard as well. Its likely there are quite a few contributory factors going on.

Anyway. CAA make the right call, I think. Two down in four months on a new type is not a great sign.

 

Edited By Nigel R on 12/03/2019 14:09:22

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CAA have made exactly the right call - for the peace of mind of the travelling public if nothing else.

If I had a flight booked on a 737-8, I'd be thinking of cancelling my tickets until the cause of the crash(es) is known and a solution implemented - even if the solution is just briefing pilots on how to deal with the problem if it occurs.

Edited By Gary Manuel on 12/03/2019 14:17:22

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Nigel R, Andrew Ray, Sorry I was refering to model aircraft.

Flap elevator mix is common these days. When I started RC flying  if flaps caused a trim change you either held it on the stick or adjusted on the trim lever which was an instant adjustment unlike todays button trims. Much like the trim wheel of some full size aircraft.

Edited By J D 8 on 12/03/2019 14:59:59

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Southwest Airlines, America's biggest Max 8 operator, found that the specifics of disabling the MCAS system had been left out of their FCOM, the aircraft ops manual.

Wait for it, from the Wall Street Journal,

“One high-ranking Boeing official said the company had decided against disclosing more details to cockpit crews due to concerns about inundating average pilots with too much information — and significantly more technical data — than they needed or could digest.”

QED.

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