Glasair III pilot reported an airspace violation occurred when his autopilot started an abrupt climb...

Attributes
ACN	1383528
Time
Date	201608
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Amateur/Home Built/Experimental
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	VFR
Person 1
Function	Single Pilot
Qualification	Flight Crew Flight Instructor Flight Crew Flight Engineer Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 28000 Flight Crew Type 765
Events
Anomaly	Aircraft Equipment Problem Less Severe Airspace Violation All Types Flight Deck / Cabin / Aircraft Event Other / Unknown

Narrative:

Flying in my experimental glasair III I was under the class B VFR at 1800-1900 feet on autopilot (garmin). With altitude hold on I was going to start a descent [so] I disengaged the autopilot (which does not have auto trim function). The aircraft was holding nose up pitch trim which I was not aware [of]; or ready for it. As it popped off; the aircraft pitched up rapidly and the suitcase I had laying next to me in the passenger seat (two seat side by side cockpit) fell between the right side control stick holding it in the aft position. I grabbed the bag; pulled it free; and pitched the aircraft back down; but I had risen to 24-2600 feet. I dove back below 2000 within a few seconds; but I did go above the 2000 floor of the class B for several seconds. What I learned is to never have a suitcase in the front seat and be aware that the autopilot; not having auto trim; can pitch up when disconnecting it. The unit has auto trim system built into it; but garmin has continued to not recognize that in my fiberglass aircraft. Their servo puts out EMI (electro magnetic interference) when trying to run the trim; causing blockage of signal to hear the radios; so the system is not operational.

Original NASA ASRS Text

Title: Glasair III pilot reported an airspace violation occurred when his autopilot started an abrupt climb after it was disconnected.

Narrative: Flying in my experimental Glasair III I was under the class B VFR at 1800-1900 feet on autopilot (Garmin). With altitude hold on I was going to start a descent [so] I disengaged the autopilot (which does not have auto trim function). The aircraft was holding nose up pitch trim which I was not aware [of]; or ready for it. As it popped off; the aircraft pitched up rapidly and the suitcase I had laying next to me in the passenger seat (two seat side by side cockpit) fell between the right side control stick holding it in the aft position. I grabbed the bag; pulled it free; and pitched the aircraft back down; but I had risen to 24-2600 feet. I dove back below 2000 within a few seconds; but I did go above the 2000 floor of the class B for several seconds. What I learned is to never have a suitcase in the front seat and be aware that the autopilot; not having auto trim; can pitch up when disconnecting it. The unit has auto trim system built into it; but Garmin has continued to not recognize that in my fiberglass aircraft. Their servo puts out EMI (Electro Magnetic Interference) when trying to run the trim; causing blockage of signal to hear the radios; so the system is not operational.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.