Narrative:

Descending into pdx with autoplt engaged from 27000 ft, I began to encounter freezing rain at approximately 17000 ft. All anti-ice system were in place prior to descent per flight manual. I continued down to 9000 ft as I crossed wylie intersection. Crossing wylie, freezing rain became mixed with ice. My aircraft began an accretion of clear ice. As I was being vectored to the northeast, then to the west, I advised approach control I was nearing a thunderstorm, but I was denied deviation due to traffic. Following the close encounter with the thunderstorm, further ice accumulation occurred, and I was then given a right hand turn to the east for downwind to runway 28R ILS. Shortly thereafter I was given a left turn/base leg toward laker OM. My airspeed was reduced from 170 KTS to 135 KTS per ATC request. At this time the aircraft began an unscheduled climb. The autoplt was still engaged. I attempted repeatedly to disengage the autoplt and the electric trim, however, the aircraft did not respond normally. Flight controls, pitch and roll, did not respond to yoke inputs. Using differential power, I was able to control pitch marginally. Maintaining assigned altitude was not possible, and I informed tower that I had a control problem. The tower gave me a 180 degree right turn, and instructed me to proceed as possible. Between 600-800 ft on final, aircraft responded normally to flight control inputs and landing was normal. Callback conversation with reporter revealed the following information: the reporter was flying his own king air B-200 with his non rated wife in the first officer seat. The reporter found himself in 'extremely heavy ice.' there was an 'autoplt glitch' in addition to the ice. He did not declare an emergency but pdx treated this as such. This is a 'fairly new aircraft.' the reporter had 'no control whatsoever' except for pitch with the engines. On the ground, mechanics found that the servos were too tight. The autoplt had to be replaced by collins who would not give the reporter an explanation of the problem. The trim wheel was trimming back without the reporter's knowledge. A FSDO representative was on hand when the aircraft was being repaired and had praise for the way the aircraft was flown.

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Original NASA ASRS Text

Title: A PVT KING AIR 200 PLT HAD AN ACFT EQUIP PROB AUTOPLT WOULD NOT DISCONNECT, AUTOPLT SERVOS TOO TIGHT, TRIM ROLLING BACK WITH NO PLT INPUT. WX FACTORS 'EXTREMELY HVY ICE.'

Narrative: DSNDING INTO PDX WITH AUTOPLT ENGAGED FROM 27000 FT, I BEGAN TO ENCOUNTER FREEZING RAIN AT APPROX 17000 FT. ALL ANTI-ICE SYS WERE IN PLACE PRIOR TO DSCNT PER FLT MANUAL. I CONTINUED DOWN TO 9000 FT AS I CROSSED WYLIE INTXN. XING WYLIE, FREEZING RAIN BECAME MIXED WITH ICE. MY ACFT BEGAN AN ACCRETION OF CLR ICE. AS I WAS BEING VECTORED TO THE NE, THEN TO THE W, I ADVISED APCH CTL I WAS NEARING A TSTM, BUT I WAS DENIED DEV DUE TO TFC. FOLLOWING THE CLOSE ENCOUNTER WITH THE TSTM, FURTHER ICE ACCUMULATION OCCURRED, AND I WAS THEN GIVEN A R HAND TURN TO THE E FOR DOWNWIND TO RWY 28R ILS. SHORTLY THEREAFTER I WAS GIVEN A L TURN/BASE LEG TOWARD LAKER OM. MY AIRSPD WAS REDUCED FROM 170 KTS TO 135 KTS PER ATC REQUEST. AT THIS TIME THE ACFT BEGAN AN UNSCHEDULED CLB. THE AUTOPLT WAS STILL ENGAGED. I ATTEMPTED REPEATEDLY TO DISENGAGE THE AUTOPLT AND THE ELECTRIC TRIM, HOWEVER, THE ACFT DID NOT RESPOND NORMALLY. FLT CTLS, PITCH AND ROLL, DID NOT RESPOND TO YOKE INPUTS. USING DIFFERENTIAL PWR, I WAS ABLE TO CTL PITCH MARGINALLY. MAINTAINING ASSIGNED ALT WAS NOT POSSIBLE, AND I INFORMED TWR THAT I HAD A CTL PROB. THE TWR GAVE ME A 180 DEG R TURN, AND INSTRUCTED ME TO PROCEED AS POSSIBLE. BTWN 600-800 FT ON FINAL, ACFT RESPONDED NORMALLY TO FLT CTL INPUTS AND LNDG WAS NORMAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FLYING HIS OWN KING AIR B-200 WITH HIS NON RATED WIFE IN THE FO SEAT. THE RPTR FOUND HIMSELF IN 'EXTREMELY HVY ICE.' THERE WAS AN 'AUTOPLT GLITCH' IN ADDITION TO THE ICE. HE DID NOT DECLARE AN EMER BUT PDX TREATED THIS AS SUCH. THIS IS A 'FAIRLY NEW ACFT.' THE RPTR HAD 'NO CTL WHATSOEVER' EXCEPT FOR PITCH WITH THE ENGS. ON THE GND, MECHS FOUND THAT THE SERVOS WERE TOO TIGHT. THE AUTOPLT HAD TO BE REPLACED BY COLLINS WHO WOULD NOT GIVE THE RPTR AN EXPLANATION OF THE PROB. THE TRIM WHEEL WAS TRIMMING BACK WITHOUT THE RPTR'S KNOWLEDGE. A FSDO REPRESENTATIVE WAS ON HAND WHEN THE ACFT WAS BEING REPAIRED AND HAD PRAISE FOR THE WAY THE ACFT WAS FLOWN.

Data retrieved from NASA's ASRS site as of July 2007 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.