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Old 30th Mar 2012, 08:53
  #1082 (permalink)  
Owain Glyndwr
 
Join Date: Jun 2011
Location: West of Offa's dyke
Age: 84
Posts: 474
JAR 25

Selected Items, Part 25—airworthiness standards: Transport category airplanes
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.
The A330 was certificated to JAR 25 Change 13, which should have been virtually identical to FAR 25 as written at that time (1980s?) I'm not sure how the FAR 25 you quote (2012?) relates to that earlier standard.

Anyway, the differences seem to be: [The emphasis and selections are mine]

JAR 25.181 Dynamic stability

contains another requirement....

(b) Any combined lateral-directional oscillations (Dutch roll) occurring between stalling speed and maximum allowable speed appropriate to the configuration of the aeroplane must be positively damped with controls free, and must be controllable with normal use of the primary controls without requiring exceptional pilot skill
Maybe marginal, but the A330 seems to meet this requirement also

JAR 25. 201 Stall demonstration has the following

(c) The following procedures must be used to show compliance with JAR 25.203
.....
(2) As soon as the aeroplane is stalled, recover by normal recovery techniques
JAR 25.205 Stall warning

(b) The warning may be furnished ......

.....

(c) ...... Stall warning must continue throughout the demonstration, until the angle of attack is reduced to approximately that at which stall warning is initiated.
Since the demonstration is supposed to be ended as soon as the aeroplane is stalled the designers would not have been expected to maintain the warning throughout 54 seconds of stall. With hindsight this requirement should be up for review.

PS. On checking, the current CS25 has removed the reference to the demonstration, which fits the bill:

Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began.

Last edited by Owain Glyndwr; 30th Mar 2012 at 10:26. Reason: additional comment
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