airbus330 wrote:scotia wrote:Lootman wrote:It wasn't a MAX. The MAX has actually been flying again for a year now, without any incidents. How many years of further incident-free travel would convince you that it is now at least as safe as any other plane out there? And possibly safer with all the extra training, testing and refinements?
I don't believe that It (the MAX and earlier 737s) is as safe as any other plane out there. Its based on a very old design, and to retain a "look and feel" to previous models (to avoid the need for crew re-training) it does not have safety features of more modern aircraft. For example, it still uses a mechanical steel cable based system for the major flight controls - with no duplication. More modern Boeing aircraft and all Airbus aircraft use an electrical system with duplication. The 737 has no fuel dump system - in an emergency with a full fuel load, the plane must loiter, or land overweight. And during the two MAX crashes, the co-pilot had to thumb through large paper-based operating manuals in an attempt to find out what was happening. In more modern planes, such information is available on a touch screen display system. Although this is now mandatory in new aircraft, it is not required in updated models. Once again, this was deliberately missed out in the MAX so that the crew interface looked like the previous versions. So its probably as safe as aircraft built more than a decade ago, but certainly not as safe as current offerings from other manufacturers (e.g. Airbus).
And looking at the causes of the MAX crashes, I was completely astonished to discover that the software had a single point of failure which crucially depended on a faulty transducer - when this could simply have been avoided by checking the two transducers that were available.
What got Boeing into this mess? Could I advise the book "Flying Blind" by Peter Robison (ISBN 978-0-241-45557-9). The author believes that the decline was caused by the merger with McDonnell-Douglas, with the Boeing engineering philosophy being taken over by the McDonnel Douglas accountancy philosophy - in particular the worship of the late Jack Welch approach (at GE - who retired with a payment of $417M in 2001).
It is also worth reading to hear about the cost savings that were introduced by out-sourcing parts for the 787 Dreamliner, and moving the construction of the major parts to lower wage areas (with less skilled employees). Just Google "Dreamliner problems" - the problems keep coming. As late as February of this year the FAA stated that it will retain the authority to issue airworthiness certificates until it is confident that "Boeing's quality control and manufacturing processes consistently produce 787s that meet FAA design standards"
All 737 flight control systems are duplex hydraulic actuated by cable systems to the hydraulic power units. The cable system can also be used, in emergency, to directly actuate the flight control surfaces, split between the 2 pilots. So effectively a third redundancy. Even the 777 has the same. Its been the standard and safe system in airliners for 50yrs and is still in newly built small airliners. Boeing came later to fly by wire when Airbus were crashing their new hi tech planes at an alarming rate 25 yrs ago. FBW and pilot understanding of the flight management systems, is at the center of investigations for quite a few serious safety incidents just now.
Extremely few shorthaul aircraft have the facility to dump fuel. It isn't necessary as all current models can land with maximum fuel on board. The only reason to dump fuel is to lose weight on a very large aircraft so that it can land under its max structural weight. The 737 has a phenomenal safety record over its life.If it anecdotally seems to be in more crashes, it is because there are so many of them flying. Even some of the 60's ones are in service. The MAX issue is different and is the result of Boeing losing its way for various HR, Financial and Engineering reasons. "If it ain't Boeing, I'm not going" has a hollow ring to it today.
Thanks for your clarifications. To be clear, I'm an electrical engineer - not an aeronautical engineer. I have experience designing control systems to load power generators via hydraulic actuators, and designing intelligent databases to ensure that there is separation of routes to remote substations from a Control centre. All commands are transmitted electrically - no steel cables. So you will probably guess that I favour electrical fly by wire.
However could you further clarify the cable systems to the hydraulic actuators, just in case I am mis-understanding their configuration. Is each control cable duplicated and separately routed - as I understand fly by wire systems are. If not - they are a single point of failure.Yes I was aware that short haul aircraft did not normally require a fuel dump system, since historically they did not exceed the permitted MTOW to MLW (max takeoff to max landing weights) ratio, but I thought that the MAX had outgrown this. I realise now that the regulations (FAR 25.473) have been loosened, and aircraft can carry out an emergency landing at the maximum take off weight provided the descent velocity is less than 6fps, and is followed by an engineering check on the landing gear. I don't know if this is common. I guess you haven't tried it.
But getting back to Boeing - what's your opinion of the 787? I think I'd prefer an alternative.
