Originally Posted by
EXDAC
Anyone here actually fly with the Century 2000? My read of the Pilot's Operating Manual makes me believe that the pitch reference is continuously changed as long as the UP or DN button is pressed. That idea was dismissed in the linked accident video.
The manual discussion of the UP DN buttons, and pitch modes in general, is very sparse but does include:
"*PITCH MODIFIER SWITCHES - The pitch modifier switches are momentary push-button type, located on the right side of the Mode Programmer, used to modify the airplane’s attitude and to shift the AP from the ALT mode to the ATT mode."
I read that as - brief push changes from ALT to ATT mode with current pitch attitude being held. If the UP or DN button is held then the ATT reference continuously changes in the direction corresponding to the held button.
Was Juan Browne right that holding UP/DN does nothing because the buttons are "momentary action" or do they continuusly change the ATT mode pitch reference?
The Century 2000 pitch adjuster perhaps operates in a similar manner as that on the Vickers Vanguard (a British 4-turboprop 1960s airliner). The control was a rocker switch spring-loaded to OFF (vertical position). A gentle push-and-hold movement lowered pitch attitude at a slow continuous rate. Releasing the switch locked the current attitude. A stronger push lowered pitch at a greater rate. Opposite movement for pitch up. If the autopilot ALT HOLD was selected it auto trimmed pitch attitude and the rocker 'gentle' mode was inop. A stronger push or pull disengaged ALT HOLD and changed pitch as described above.