Hi rrr,
Since the aircraft is no longer "protected" in Alt Law, how did the certification process of A330 satisfy:
Section 5. Stability
26. Static Longitudinal Stability and Demonstration of Static Longitudinal Stability -
§§ 25.173 and 25.175175. ?
http://www.faa.gov/documentLibrary/m...2025-7C%20.pdf
Well of course the document you reference is an AC not a requirement, but the answer to your question I think is that there is a Special Condition for A330/A340 certification against JAR 25.173 and 25.175 (EASA TCD A015 Annex; Special Condition F3):
The aircraft shall be shown to have suitable stability in any condition normally encountered in service, including the effects of atmospheric disturbances.
Interpretative material:
The evaluation of the aeroplane's static longitudinal stability characteristics shall be by flight and simulator tests. Control laws that result in neutral static stability throughout most of operational flight envelope may be accepted in principle subject to:
- adequate speed control without excessive pilot workload
- acceptable high and low speed protection
- provision of adequate cues to the pilot of significant speed excursions beyond VMO/MMO and below take-off and landing scheduled speeds.
The following considerations will be relevant to the evaluation:
- accurate speed control will be particularly relevant in the full range of operating speeds including low speeds (scheduled speeds at take-off and landing with or without engine failed) and high speeds for each configuration including VMO/MMO
- Since conventional relationships between stick forces and control surface displacements do not apply to a manoeuvre demand control system, longitudinal static stability characteristics will need to be determined on the basis of the aeroplane's response to disturbances rather than simply on the basis of stick force versus speed gradients.
- Adequate high or low speed cues may be provided by a strong positive stability gradient and/or alerting system.
- A force gradient of 1 lb for each 6 knots, applied through the side-stick, shall be considered as providing this strong stability