Granted the A330 was not certified initially under US guidelines, but I thought it interesting to see how well it met US standards. As the title says, this is selected information by me.
§ 25.181 Dynamic stability.
(a) Any short period oscillation, not including combined lateral-directional oscillations, occurring between 1.13 VSRand maximum allowable speed appropriate to the configuration of the airplane must be heavily damped with the primary controls—
(1) Free; and
(2) In a fixed position.
It would seem that the A330 meets this standard very well...............until it gets into Alt2 Law. Then in is not heavily damped in roll.
§ 25.201 Stall demonstration has some interesting specifications:
(3) As soon as the airplane is stalled, recover by normal recovery techniques.
(d) The airplane is considered stalled when the behavior of the airplane gives the pilot a clear and distinctive indication of an acceptable nature that the airplane is stalled. Acceptable indications of a stall, occurring either individually or in combination, are—
(1) A nose-down pitch that cannot be readily arrested;
(2) Buffeting, of a magnitude and severity that is a strong and effective deterrent to further speed reduction; or
(3) The pitch control reaches the aft stop and no further increase in pitch attitude occurs when the control is held full aft for a short time before recovery is initiated.
AF447 seems to have demonstrated #1 and #3 a number of times during the prolonged stall.
#2 Buffeting apparently was not a strong and effective deterrent to the crew of AF447 and the Captain back in the cabin apparently did not recognize it either.
Is this knowledge well known among crews in general?
Shouldn't it be? Suppose your stall warning system fails?
§ 25.207 Stall warning.
(b) The warning must be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under expected conditions of flight. However, a visual stall warning device that requires the attention of the crew within the cockpit is not acceptable by itself. If a warning device is used, it must provide a warning in each of the airplane configurations prescribed in paragraph (a) of this section at the speed prescribed in paragraphs (c) and (d) of this section.
It has been discussed a number of times in the AF447 threads, but the amazingly minimal response of the crew to the audible stall warning indicates to me that the concept of stall warning needs better human interface engineering in general.
For example, Colgan overrode his stick pusher! Maybe what is needed is not more force, but something that is harder to ignore. I really liked my pedal shaker in the Phantom, but the stick shaker is more applicable to the airline environment. Has anyone seen a better warning system? We do not seem to have quite the correct solution yet.
Here is your link to the reference:
Electronic Code of Federal Regulations: