Hi, just did a nice flight from Vegas to Sedona in the Kingair and all perfect except one thing I realized also in earlier flights but before I file a bug with Zendesk I want to make sure that it's not my fault since I am not familiar with the Kingair's AP behaviour. 

So I fly towards my pattern entry with AP ALT and NAV/HDG enabled. Once reaching the last waypoint I "just" took over the plane without expressly disconnecting the AP in my uneducated assumption that the AP would disconnect automatically. Well, to some extent it did as I could fly the plane but it was very hard to control, gave me various stall warnings at around 120kts until I realized that elevator trim was fully up. Trim down did not work until I pressed the master AP switch, only then I was able to trim the a/c correctly and land. 

In essence my question is whether the fully trim up effect is a bug or a real live behaviour cause I did not deactivate the AP before, 

Thanks

No AP/YD will not automatically disconnect unless you meet one of the disconnect criteria. You would have been fighting the controls and at some point would most likely exceeded a servo pressure limitation and the AP would have disconnected (after some major struggling.) The YD would have most likely remained on. However, as soon as you trimed the aircraft the AP would have disconnected and YD remained on.

When you want to take control of a King Air with a Collins based AFCS you should get used to pressing the AP/YD (red button) to the first detent.

well, if I remember correctly then PMDGs 737 AP did disconnect automatically. but thanks for your explanation, will try to remember to flip that button next time also in the Kingair before just taking over. Obviously other disconnect criteria, thanks for clarifying. so no bug but rather a pilot error in my case. learned something. though I strongly believe that I did trim the King Air down manually using the button assigned to it on my yoke but the AP always trimmed against me again. so no disconnnect here either. will check next time and verify

I think that is a PMDGism, however I am NOT a rated 737 pilot.  Boeing describes the 737NG disconnect criteria as:

Quote

Autopilot Disengagement

The A/P automatically disengages when any of the following occurs:
• pushing either A/P disengage switch
• pushing either Takeoff/Go–around (TO/GA) switch with a single A/P engaged in CWS or CMD below 2000 feet RA
[Option - A/P auto-disengages for TO/GA above 2000 feet RA]
[Option - Honeywell -708 FCC]
• pushing either Takeoff/Go-around (TO/GA) switch with a single A/P engaged in CWS or CMD above 2000 feet RA with flaps down or G/S engaged.
• pushing either TO/GA switch after touchdown with both A/Ps engaged in CMD
• pushing an illuminated A/P ENGAGE switch
• pushing the A/P DISENGAGE bar down
• activating either pilot’s control wheel trim switch
• moving the STAB TRIM AUTOPILOT cutout switch to CUTOUT
• either left or right IRS system failure or FAULT light illuminated
• loss of electrical power or a sensor input which prevents proper operation of the engaged A/P and mode
• loss of respective hydraulic system pressure.

Note: Loss of the system A engine-driven hydraulic pump, and a heavy demand on system A, may cause A/P A to disengage.