Posted on 03/10/2020 3:13:13 PM PDT by Yo-Yo
The COVID-19 is airborne..
But every single MAX aircraft already does have two AOA probes. One drives the Captain's instrumentation and one drives the First Officer's side.
Boeing wrote the MCAS software to use just one AOA probe, either the Captain's or the FO's, alternating every other flight. The problem came when Boeing wrote the flight display software, there was supposed to be an error flag "AOA DISAGREE" on the flight display unit if the two AOA sensors disagreed by more than 10 degrees.
However, the way the software was ultimately written, the AOA DISAGREE error flag was only active on those aircraft where the optional AOA display was purchased. If you didn't buy the optional AOA display, you didn't get the AOA DISAGREE warning.
Boeing knew of this problem, and had planned on quietly correcting it in a future software update, but the two crashes occurred, the MAX was grounded, and the whole software error fiasco was exposed.
Boeing's proposed fix to the MAX aircraft is to activate the AOA DISAGREE warning on all aircraft, and to disable MCAS completely if the two AOA probes are in disagreement.
And an erratic altimeter reading would be caused by an obstructed static pressure port, not an AOA probe.
Thanks for the info. There’s lots there I didn’t know.
Yes, an obstructed static port can also cause an erratic altimeter reading also. But I know from my own repair experience that a dirty AOA probe will cause WILDLY erratic readings.
Boeing was made the responsible party because they had the financial resources to compensate the victims and juries view them as greedy and evil. They forget that Boeing employees and families fly on the same aircraft as everyone else and have the best safety record of any aircraft manufacturer in the world. I would fly comfortably on any aircraft that the pilot and first officer put their own lives on.
One of the reasons why they wouldn’t let The NTSB near this is they wanted to stick to Boeing rather than admit they short change their crews.. Both Airlines..
Yep - them 3rd world pilots are like the folks who panic over coronavirus then don’t bother to take proper precautions...
There are two types of AOA sensors. Supersonic aircraft, like the F-111A that I worked on, usually have the pressure differential type, and subsonic aircraft including most Airbus and Boeing aircraft, including the MAX, use the vane type.
I suspect that in your Air Force days, like mine, that the pressure differential type of AOA sensor was used, and the air pressure was also used somehow in the altimeter.
The MAX uses the vane type, and cannot possibly affect the altimeter.
Thanks for the diagram. Yes, the F-4D had a pressure differential type of AOA like the one in the diagram.
I wasn’t trying to imply that the MAX crashes were caused by faulty altimeter readings, rather my comments about the wild altimeter readings were intended to point out that AOA information can be wildly inaccurate at times.
From what I’ve read, the MAX uses AOA information fed into a system which then controls the flight surfaces. I believe that the MAX crashes may have been caused by faulty AOA readings that made the system “think” it was in a stall situation, when in fact, it was not.
I remember the F-4’s AOA system because we had so much trouble with it - the altimeter problems. But I also worked on some Boeing built planes, the KC-135, the RC-135, and the EC-135 when I was at Offutt for 6 months. I don’t even remember the AOA system on these aircraft so they were probably pretty reliable but probably had the vane type of AOA probe. But I think the vane type would be just as susceptible to corrosion as the probe type because the problems were inside the housing and not in the probe itself (unless the heater wasn’t working).
FYI: The static ports on the F-4D were located on the side of the Radome and this may be why they had to correct the raw static information for changing AOA. Also, the flushness of the static port itself was crucial. The F-4E models (and I think the C models) had a probe that stuck out in front of the planes, but I never worked on those model so I don’t know whether or not these other models changed the static information based on AOA inputs.
— libertylover
“The important thing is how many wimmens they have on their board. “
What’s the threshold for calling it a “Broad Board”?
If they did have the needed info why is Boeing cratering now?
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