Date: 201204
Local time of day: 0001-0600
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Weather elements / visibility: Turbulence; 10
Light: Daylight
Aircraft: SA-226 TC Metro II
Operator: Corporate
Operating under: Part 91
Flight plan: None
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Autoflight System
Component problem: Design; Malfunctioning
Reporter organization: Air Taxi
Reporter function: Single Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness; Distraction
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: On Climb out from ZZZ enroute to ZZZ1 I noticed traffic on my Ryan TCAD that was approximately 2NM and 2;000 FT above. Since the floor of the Class B in this area is 4000 FT MSL; and the traffic was approximately 5;000 MSL I stopped my climb at 3;500. This gave a separation of 1;500 FT altitude from myself and the traffic reported by TCAD. After the traffic dropped off of the TCAD I resumed a slow climb to 3;900 at which altitude I stopped because I had another 1 or 2 NMs left before clearing the outer boundary of Houston's Class B. I engaged the altitude hold on the autopilot to check the ZZZ2 ATIS and the ZZZ3 ATIS to verify altimeter settings.The reason for the ATIS check was that the other aircraft was showing 1;600 FT higher instead of an 'even' 1;500. Obviously ZZZ2 was using a different altimeter setting that ZZZ.  I looked over after selecting the appropriate frequencies and noticed my altitude was indicating 4;020 FT MSL and that the autopilot had tripped off. I was within 1 NM (still inside) of the Class B boundary and when I reset my altimeter to ZZZ2's reported altimeter. I was then indicating 3;960 FT MSL. I was indicating 4;020 but in fact I was at an actual 3;960.  A check of my other altimeter and TCAD altitude showed 3;900.  I was at all times; outside of the Class B.  I use the recommended Class B flyway altitudes and began my climbout just a little early.I never broke the 4;000 FT floor of the Class B; but I also acknowledge that I should be a little more patient when leaving the recommended flyway altitudes. There was no traffic in my vicinity after clearing the TCAD reported aircraft.  I should have stayed at 3;500 until clearing the Class B boundary.  The most important report that I can give is the fact that the Rockwell Collins APS 80 flight control system gives no aural warning when it disengages by itself.  I have had the same problem with all Collins autopilots I have flown;over the course of my career. APS 80; AP 105; 108; and 106's.  I once was three miles off course in another airplane with an AP 106; while setting up a FMS due to the AP 106 disengaging and since there is no warning; not made aware of it sooner (you can only know by looking at the small annunciators-diffficult to see in daylight).




Synopsis: A SA226 pilot operating under Class B Airspace reported that the Rockwell Collins autopilot disengaged without issuing a warning which almost allowed the aircraft to climb into the Class B as he checked ATIS altimeter.