Beechjet 400
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation - Altitude Overshoot
Flight Crew Overcame Equipment Problem; General Maintenance Action
Human Factors; Aircraft
Third leg of the day; we departed on a flight to PWK. We were assigned 2;000 FT. PIC was hand flying the airplane; I was running the after takeoff checklist. I heard the warning sound of the trim; and looked over to see the PIC pressing the yoke full forward and the airplane climbing through 1;900 FT. I immediately pressed and held the AP/Trim disconnect red button; when the PIC noticed the 'Hat' on his side had gotten stuck in the nose up position. We briefly hit 2;300 FT and descended back to 2;000 FT. The rest of the flight was uneventful; and we were never queried by ATC. Pitch trim was written up and ops check found it to be ok.
BE400 Captain as the pilot not flying in the right seat hears the trim warning sound and notes the pilot flying struggling to level off at 2;000 FT. The autopilot/trim disconnect switch is pressed and held by the pilot not flying as the pilot flying detects the trim switch 'hat' is stuck in the nose up position. The remainder of the flight is uneventful and Maintenance can find no faults.