Gulfstream G200 (IAI 1126 Galaxy)
Flight Crew Commercial; Flight Crew Multiengine
Flight Crew Last 90 Days 20; Flight Crew Total 2200; Flight Crew Type 250
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem; Flight Crew Regained Aircraft Control
Aircraft
I was Pilot in Command and the Pilot Flying after a normal takeoff climbing out from ZZZ. Gear was up and we were turning to a heading of 320 with the auto-pilot (AP) engaged set to level at 3000 feet. Almost immediately after leveling at 3000 feet the plane pitched aggressively up and started climbing. I immediately disconnected the autopilot and pitched down and trimmed down but there was real resistance (felt like a runaway trim). I believe the highest we climbed was 4000-4500 feet. My copilot pushed down with me to adjust altitude and he requested a heading and block altitude from ATC while we evaluated the situation. We hand-flew the plane.Having three options of landing overweight (we were above max landing weight); dump fuel or continue; as we were going to a Maintenance Facility we opted to continue to our destination and trouble shoot/monitor closely the situation.I advised my copilot to couple the AP to his side and try to re-engage the AP. We had enough fuel to fly to our destination at an altitude below 28;000 feet but since the AP was operating normally on the right side we continued flight with it operating uneventfully in that position in RVSM (FL400-FL410). We reacted immediately and advised ATC immediately after taking rapid corrective action. We train for this and will continue to do so. I am sorry if we caused aggravation and we appreciate the immediate assistance provided to us by ATC.
[Report narrative contained no additional information.]
G200 flight crew reported a malfunction with one autopilot shortly after level off from climb. Crew switched to other autopilot and continued to the destination.