Originally Posted by
FCeng84
jimtx - I fully agree with you that wind-up turns are not a normal maneuver. They are fun to experience during flight testing, but I hope no fare paying passenger on a regular transport flight has to ride through one. Wind-up turns are the test maneuver most commonly used to collect data to demonstrate compliance with stick force vs. g requirements as specified in FAR 25. The overall objective is that increases in nose up controller forces as applied by the pilot will be required in order to command higher load factors (i.e., higher AOA at a given speed). This is considered necessary to provide the pilot with an airplane that enables control of load factor at elevated levels if the pilot chooses to command the airplane there and similarly that the airplane will promptly recover to more normal load factors if that is the intent of the flight crew.
In addition to wind-up turns, flight testing also often includes roller coaster maneuvers (wings level pull-ups and push-overs in succession). These are probably more relevant to line operation maneuvers such as vertical maneuvers to change climb/descent angle, avoidance maneuvers prompted by see-and-avoid or TCAS, and tight path control during an emergency descent. Those maneuvers are more dynamic than wind-up turns so the data collected during those handling qualities evaluations does not lend itself very well to showing compliance with the FAR force vs. maneuver requirements. For that compliance, wind-up turn data has been the standard.
So FAR part 25 has requirements for the ac aerodynamics (?) to provide the pilot with an airplane that enables him to control load factors with a linear stick pull and not have the the surprise of the ac continuing to pull load factor when the pilot is not requesting it? But FAR25 does not care about the actual aerodynamics, in the 737Max, as the autopilot is not protected from the stick force non linearity, rightfully so, as it doesn't care about sick force? So the ac's aerodynamics do not have to be adjusted. The only adjustment needed is to fool the pilot that he has to pull harder to get more g or AOA? And, if the pilot loses this MCAS, Boeing doesn't even tell him to be careful in any flight regime as he will not encounter it in normal operations. Although you alluded to some escape maneuvers that might approach the MCAS envelope. But the current abnormal runaway trim procedure, where MCAS will be disabled, that Boeing advertises as sufficient, does not caution about being careful in a TCAS maneuver or an escape maneuver. Because a Boeing exec said that pilots do not have to know about the nuances of the ac. But of course, nobody is going to get runaway trim and then get a TCAS alert or an escape situation on the same day.