Cessna 425/441 Conquest I/Conquest II
Flight Crew Commercial; Flight Crew Multiengine
Flight Crew Last 90 Days 72.8; Flight Crew Total 2617; Flight Crew Type 800
Human-Machine Interface; Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance
Flight Crew Overcame Equipment Problem; Flight Crew Became Reoriented
Human Factors; Aircraft
Leveled off in climb at FL230.  After 15 min the aircraft pitched down and elevator trim rolled hard forward; disconnected auto pilot and flew the airplane by hand.  Stabilized airplane; adjusted elevator trim manually.  Re-engaged the autopilot and aircraft flight was normal with slight very slow oscillations 30-50 feet up and down.  I was asked to switch to next frequency; confirmed and switched.  Called in and I waited for response. Shortly after this the aircraft pitched down again and I disengaged the autopilot; I stabilized the aircraft again and flew by hand with autopilot in heading mode only.  At this time I started going through the flight manual for further information on the autopilot setup functions. At this time I got a call on 121.5 that center was looking for me with a new frequency.  I called and re established contact. The cause of the problem was possible a miss interruption of the new frequency and that I was distracted by the autopilot malfunction.  Following this there were a couple of times that the frequency that I was on got quiet; and on 2 occasions I called ATC to verify 2-way communication.  In the future verify the frequency and make sure you get a response when changing to a new frequency.
C414 pilot experiences a runaway elevator trim with the autopilot engaged and takes over manually. The elevator is retrimed and the autopilot re-engaged. During this time a frequency change is issued and contact with the next Controller is never established.