[SystemSafety] "FAA chief '100% confident' of 737 MAX safety as flights to resume"

Olwen Morgan olwen at phaedsys.com
Thu Dec 3 12:59:48 CET 2020

Having admitted to my execrable knowledge of aerodynamics and 
aeronautical engineering, I will now make a few ill-informed 
speculations about the 737 MAX:

Consider the following situation without MCAS:

At a certain speed and AoA, the pitch-up tendency of the aircraft is 
beginning and the force on the stick has started to lessen. AFAI can 
see, lessening of stick force will be due to reduced aerodynamic 
pressure on the HS and elevators. If the HS and elevators are exerting a 
much reduced force against the oncoming air-stream, then their ability 
to control pitch has been correspondingly lessened. At the same time, 
the pitch-up tendency is bringing the wing closer to a stall condition. 
If the aircraft progresses to a wing-stall condition and at the same 
time is suffering reduced pitch control as a result of what is 
happening/has happened to the air flow over the HS and elevators, then 
that condition is very close to a much more dangerous *deep stall* 

Call me a scaredy-cat - or even just a pig-ignorant old bag - but I 
personally don't think that any civil airliner airframe should exhibit 
aerodynamic behaviour that introduces such a risk of a deep stall.

And now I'll just let PBL hurl his customary bile at me.


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