C414 pilot experiences a runaway elevator trim with the autopilot engaged and takes over manually. T...

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.

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.

Attributes
ACN	1222311
Time
Date	201412
Local Time Of Day	0601-1200
Place
Locale Reference	S46.TRACON
State Reference	UT
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna 425/441 Conquest I/Conquest II
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Elevator Trim System
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 72.8 Flight Crew Total 2617 Flight Crew Type 800
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance

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.