Narrative:

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.

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Original NASA ASRS Text

Title: 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.

Narrative: 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.

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.