during flight i had to perform a emergency descent, to avoid coallision with other aircraft. AP switched off.after establishing normal flight level, i wanted to connect with cmd a again, but i could only connect with cmd b to fly with autopilot.Is this explained somewhere in the manual, i couldn't find it.Ton van Dongen

It shouldn't matter since you were able to activate B, but did you have any pressure on the yoke that may have prevented the connection. It seems you'd have the same problem connecting B if this was the case... just a thought.

Did you disengage the A/P before performing the maneuver? That's why there's a A/P Disengage switch on the control wheel."While any autopilot is engaged in CMD mode, yanking at thecontrols really hard will result in "breaking" the controller shearrivets (real value 110lbs of force) and destroy the onside FCC(flight control center). The associated autopilot cannot be reengaged."Introduction, page 116.

That's good to know... I have had the same issue before but had not taken the time to delve into what I was doing wrong. I should probably sit down and RTFM sometime.

I should probably sit down and RTFM sometime.

Even if not the whole FCOM, at least the intro.

Never known that it's actualy a hardware connection, not a software!!

Did you disengage the A/P before performing the maneuver? That's why there's a A/P Disengage switch on the control wheel."While any autopilot is engaged in CMD mode, yanking at thecontrols really hard will result in "breaking" the controller shearrivets (real value 110lbs of force) and destroy the onside FCC(flight control center). The associated autopilot cannot be reengaged."Introduction, page 116.

When your janking the control wheel or column with the A/P is the CMD mode will not break the shear rivets of the applicable A/P actuator.When you apply a force of approx 25 lbs on the control wheel or column will the disengage the A/P CMD mode or when you apply a force of approx 50 lbs with both A/P's in CMD mode will disengage both A/P's. The shear rivets of the applicable A/P actuator will only break when the A/P actuator jams and you apply a force of approx 100 lbs at the controls.