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Old 13th Jun 2010, 14:54
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Mansfield
 
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AC 25-7, Flight Test Guide For Certification of Transport Category Airplanes, Chapter 8, Para 228(b) states the following:
Some airplanes require artificial stall warning systems, such as stick shakers, to compensate for a lack of clearly identifiable natural stall warning to show compliance with the stall warning requirements of § 25.207. Similarly, some airplanes require a stall identification device or system (e.g., stick pusher, automatic inboard slat segment retraction, auto-trim, etc.) to compensate for an inability to meet the stalling definitions of § 25.201 or the stall characteristics requirements of § 25.203.
The stick pusher does not function as a stall warning device; that is the purpose of the stick shaker. The pusher is a stall identification device. It represents exactly the same thing as CLmax, and is used when CLmax either cannot be clearly identified or when the stall characteristics around CLmax are particularly unsatisfactory.

With respect to stall testing, the manufacturer does indeed conduct stall testing in flight, including at altitude. I have appended additional excerpts from AC 25-7A below. This language may give a better understanding of the issue from the authorities point of view.

I suspect that any new material on this topic from the manufacturers is a result of a rather extensive effort being put forth in the industry to understand loss of control accidents. I believe it would be a mistake to assume that it originates solely with the Buffalo accident.

AC 25-7A, Chapter 2, Section 6 – Stalls.

b. Explanation.
(1) The purpose of stall testing is threefold:
(i) To define the minimum inflight airspeeds and how they vary with weight, altitude, and airplane configuration (stall speeds).

(ii) To demonstrate that handling qualities are adequate to allow a safe recovery from the highest angle of attack attainable in normal flight (stall characteristics).

(iii) To determine that there is adequate pre-stall warning (either aerodynamic or artificial) to allow the pilot time to recover from any probable high angle of attack condition without inadvertently stalling the airplane.
(2) During this testing, the angle of attack should be increased at least to the point where the following two conditions are satisfied:
(i) Attainment of an angle of attack measurably greater than that for maximum lift, except when the stall is defined by a stall identification device (e.g., stick pusher).

(ii) Clear indication to the pilot through the inherent flight characteristics or stall identification device (e.g., stick pusher) that the airplane is stalled.
(3) The airplane is considered to be fully stalled when any one or a combination of the characteristics listed below occurs to give the pilot a clear and distinctive indication that he should stop any further increase in angle of attack, at which time recovery should be initiated using normal techniques. The stall speed is defined as the minimum speed reached during the maneuver, except for those airplanes that require stall identification devices (see paragraph 29b(3)(iv), below).
(i) The pitch control reaches the aft stop and is held full aft for two seconds, or until the pitch attitude stops increasing, whichever occurs later. In the case of turning flight stalls, recovery may be initiated once the pitch control reaches the aft stop when accompanied by a rolling motion that is not immediately controllable (provided the rolling motion complies with § 25.203(c)).

(ii) An uncommanded, distinctive and easily recognizable nose down pitch that cannot be readily arrested. This nose down pitch may be accompanied by a rolling motion that is not immediately controllable, provided that the rolling motion complies with § 25.203(b) or (c), as appropriate.

(iii) The airplane demonstrates an unmistakable, inherent aerodynamic warning of a magnitude and severity that is a strong and effective deterrent to further speed reduction. This deterrent level of aerodynamic warning (i.e., buffet) must be of a much greater magnitude than the initial buffet ordinarily associated with stall warning. An example is a large transport airplane that exhibits “deterrent buffet” with flaps up and is characterized
by an intensity that inhibits reading cockpit instruments and would require a strong determined effort by the pilot to increase the angle of attack any further.

(iv) The activation point of a stall identification device that is a strong and effective deterrent to further speed reduction. Paragraph 228 of this AC presents guidance material for demonstrating compliance of stall identification systems with the regulatory requirements of Part 25 of the FAR.
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