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by K0balt
491 days ago
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Unfortunately, it seems that the internal FAA recommendations were not allowed to make their way into any kind of airworthiness directive. The recommendations include very basic procedure changes that mitigate the near term risks without any significant impact to operation, as well as recommendations for what probably amounts to a software change and upgrades to some of the pilot oxygen masks to effect a permanent fix. The only reason that we even know about the internal recommendations is that they were leaked to the press. Boeing released a pilot bulletin that basically says to go through the checklist quickly and to treat smoke in the cabin as a major failure, but stops short of recommending some very, very simple steps in aircraft configuration prior to takeoff that would completely mitigate the issue without negatively effecting flight performance. The major recommendation in the internal FAA bulletin is to use the APU bleed instead of the main engine bleed air to power the air conditioning and cabin pressurisation during the takeoff phase of flight, below 3000 feet AGL. I can see no reason to drag feet on this recommendation, other than the uncomfortable suggestion that perhaps this issue should have been addressed during certification. (It is yet another difference from older 737 design , like the deadly MCAS system, that was not disclosed to pilots transitioning to the new aircraft) |
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Well, the configuration changes during takeoff mitigate the issue if it happens during takeoff. If it happens at any other time then they don’t do anything to help.
> I can see no reason to drag feet on this recommendation […]
I can. Perhaps the FAA believes that it is better to minimize change fatigue. Since the problem can apparently be fixed in software, and Boeing has decided to make that fix, they might want to write just one airworthiness directive requiring everyone to install it instead of two, one telling pilots to adopt some procedure followed by another telling them to abandon it.
> (It is yet another difference from older 737 design , like the deadly MCAS system, that was not disclosed to pilots transitioning to the new aircraft)
Keep in mind that for most aircraft the airline can pick and choose between different engines. The pilots don’t have to learn the myriad different engineering decisions that go into those engines; from the pilot’s perspective they are supposed to be interchangeable.