Narrative:

In the fifteen months that I have owned this plane, I have had enumerable problems with the ADI and the autoplt. In fact, on this particular trip to alaska, we lost our ADI and had to have it rebuilt with less than 300 hours on the plane. The autoplt was not dependable on the approach mode. It sometimes had a tendency to either climb or descend while showing it was coupled. The other feature that was never resolved was that if you put in the flight director in the heading and altitude hold and then turned the autoplt on, you would either go into a radical climb or descent. On the day of the occurrence, I was in seattle on boeing field at FBO and asked to talk to one of their avionics people. I spoke to avionics man and told him what it had been doing. He suggested that I try to get someone from xyz to ride with me and demonstrate it. He also told me of a small aircraft model Y when the autoplt was engaged, the plane became inverted and he had an xyz representative come and ride with him and went through the scenario that led up to the event and the plane became inverted with the xyz representative in the plane. After talking to him, we left boeing field enroute to great falls, mt, on victor 120 and we were at 13000', mostly above the clouds but occasionally just going through the tops of some cumulus. I asked for and received clearance to 14000'. I started to climb by using the climb mode on the autoplt and we hit some turbulence. At that point we were at approximately 13500' and I left the autoplt alone and was in a straight and level flight. We encountered more turbulence which was close to severe and suddenly the plane went into a vertical dive. I waited a few seconds to see if the autoplt would recover. It did not. I pulled back on the throttle and threw the switch off on autoplt. However I was too busy to see if the annunciator light went out. The switch was off on the console. The next thing I reached for was the gear switch and lowered the gear. We came out of the clouds and were in a steep dive. At that point I pulled the plane out regardless of possible damage as I felt that we had little to no chance to retain level flight. We did level off and my wife, who was with me, and I concurred that we leveled out at 6000', which only by the grace of god was adequate, as we were well below the mountains and happened to be in a valley. I did lose flight direction at that point as we turned sharply to the left and headed for a mountain and while I was trying to turn to the right, we did finally proceed to turn right and went 180 degree toward another mountain and then to the left at 45 degree toward another mountain and finally we worked our way towards a pass and leveled off at about 3000'. We called center and told them of our problem and informed them that we wanted to land at the nearest airport. The nearest one had a runway of only 2000' and we did not feel that this was adequate as the trim was frozen and I could not move it no matter what force I used. It was frozen in a climb position and it took considerable pressure from myself and I asked my wife to help to maintain level flight. The next airport was eat and they had 5000' and 18 miles away. We proceeded to fly there and I made a circle over the airport and tried to get the feel of adjusting the power to make a reasonably safe landing. We then landed by adjusting the power and had an uneventful landing. I am very concerned that these autoplts that have been giving pilots trouble, and I understand that there have been several occasions where they have not been able to be disengaged, are not replaced. They seem to be dedicated to the xyz a/P which was in the 1985 and 1986 planes. These autoplts, in my opinion, are an accident waiting to happen and I think that there has been enough documentation that should result in either the replacement of these units or find out what the probable cause is.

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Original NASA ASRS Text

Title: GA SMA AUTOPLT FAILURE PUT ACFT INTO UNCONTROLLED FLT TOWARD TERRAIN AND CAUSED LOSS OF ACFT CONTROL.

Narrative: IN THE FIFTEEN MONTHS THAT I HAVE OWNED THIS PLANE, I HAVE HAD ENUMERABLE PROBLEMS WITH THE ADI AND THE AUTOPLT. IN FACT, ON THIS PARTICULAR TRIP TO ALASKA, WE LOST OUR ADI AND HAD TO HAVE IT REBUILT WITH LESS THAN 300 HOURS ON THE PLANE. THE AUTOPLT WAS NOT DEPENDABLE ON THE APCH MODE. IT SOMETIMES HAD A TENDENCY TO EITHER CLIMB OR DESCEND WHILE SHOWING IT WAS COUPLED. THE OTHER FEATURE THAT WAS NEVER RESOLVED WAS THAT IF YOU PUT IN THE FLIGHT DIRECTOR IN THE HEADING AND ALTITUDE HOLD AND THEN TURNED THE AUTOPLT ON, YOU WOULD EITHER GO INTO A RADICAL CLIMB OR DESCENT. ON THE DAY OF THE OCCURRENCE, I WAS IN SEATTLE ON BOEING FIELD AT FBO AND ASKED TO TALK TO ONE OF THEIR AVIONICS PEOPLE. I SPOKE TO AVIONICS MAN AND TOLD HIM WHAT IT HAD BEEN DOING. HE SUGGESTED THAT I TRY TO GET SOMEONE FROM XYZ TO RIDE WITH ME AND DEMONSTRATE IT. HE ALSO TOLD ME OF A SMA MODEL Y WHEN THE AUTOPLT WAS ENGAGED, THE PLANE BECAME INVERTED AND HE HAD AN XYZ REPRESENTATIVE COME AND RIDE WITH HIM AND WENT THROUGH THE SCENARIO THAT LED UP TO THE EVENT AND THE PLANE BECAME INVERTED WITH THE XYZ REPRESENTATIVE IN THE PLANE. AFTER TALKING TO HIM, WE LEFT BOEING FIELD ENROUTE TO GREAT FALLS, MT, ON VICTOR 120 AND WE WERE AT 13000', MOSTLY ABOVE THE CLOUDS BUT OCCASIONALLY JUST GOING THROUGH THE TOPS OF SOME CUMULUS. I ASKED FOR AND RECEIVED CLRNC TO 14000'. I STARTED TO CLIMB BY USING THE CLIMB MODE ON THE AUTOPLT AND WE HIT SOME TURBULENCE. AT THAT POINT WE WERE AT APPROX 13500' AND I LEFT THE AUTOPLT ALONE AND WAS IN A STRAIGHT AND LEVEL FLT. WE ENCOUNTERED MORE TURBULENCE WHICH WAS CLOSE TO SEVERE AND SUDDENLY THE PLANE WENT INTO A VERTICAL DIVE. I WAITED A FEW SECONDS TO SEE IF THE AUTOPLT WOULD RECOVER. IT DID NOT. I PULLED BACK ON THE THROTTLE AND THREW THE SWITCH OFF ON AUTOPLT. HOWEVER I WAS TOO BUSY TO SEE IF THE ANNUNCIATOR LIGHT WENT OUT. THE SWITCH WAS OFF ON THE CONSOLE. THE NEXT THING I REACHED FOR WAS THE GEAR SWITCH AND LOWERED THE GEAR. WE CAME OUT OF THE CLOUDS AND WERE IN A STEEP DIVE. AT THAT POINT I PULLED THE PLANE OUT REGARDLESS OF POSSIBLE DAMAGE AS I FELT THAT WE HAD LITTLE TO NO CHANCE TO RETAIN LEVEL FLT. WE DID LEVEL OFF AND MY WIFE, WHO WAS WITH ME, AND I CONCURRED THAT WE LEVELED OUT AT 6000', WHICH ONLY BY THE GRACE OF GOD WAS ADEQUATE, AS WE WERE WELL BELOW THE MOUNTAINS AND HAPPENED TO BE IN A VALLEY. I DID LOSE FLT DIRECTION AT THAT POINT AS WE TURNED SHARPLY TO THE LEFT AND HEADED FOR A MOUNTAIN AND WHILE I WAS TRYING TO TURN TO THE RIGHT, WE DID FINALLY PROCEED TO TURN RIGHT AND WENT 180 DEG TOWARD ANOTHER MOUNTAIN AND THEN TO THE LEFT AT 45 DEG TOWARD ANOTHER MOUNTAIN AND FINALLY WE WORKED OUR WAY TOWARDS A PASS AND LEVELED OFF AT ABOUT 3000'. WE CALLED CENTER AND TOLD THEM OF OUR PROBLEM AND INFORMED THEM THAT WE WANTED TO LAND AT THE NEAREST ARPT. THE NEAREST ONE HAD A RWY OF ONLY 2000' AND WE DID NOT FEEL THAT THIS WAS ADEQUATE AS THE TRIM WAS FROZEN AND I COULD NOT MOVE IT NO MATTER WHAT FORCE I USED. IT WAS FROZEN IN A CLIMB POSITION AND IT TOOK CONSIDERABLE PRESSURE FROM MYSELF AND I ASKED MY WIFE TO HELP TO MAINTAIN LEVEL FLT. THE NEXT ARPT WAS EAT AND THEY HAD 5000' AND 18 MILES AWAY. WE PROCEEDED TO FLY THERE AND I MADE A CIRCLE OVER THE ARPT AND TRIED TO GET THE FEEL OF ADJUSTING THE POWER TO MAKE A REASONABLY SAFE LNDG. WE THEN LANDED BY ADJUSTING THE POWER AND HAD AN UNEVENTFUL LNDG. I AM VERY CONCERNED THAT THESE AUTOPLTS THAT HAVE BEEN GIVING PLTS TROUBLE, AND I UNDERSTAND THAT THERE HAVE BEEN SEVERAL OCCASIONS WHERE THEY HAVE NOT BEEN ABLE TO BE DISENGAGED, ARE NOT REPLACED. THEY SEEM TO BE DEDICATED TO THE XYZ A/P WHICH WAS IN THE 1985 AND 1986 PLANES. THESE AUTOPLTS, IN MY OPINION, ARE AN ACCIDENT WAITING TO HAPPEN AND I THINK THAT THERE HAS BEEN ENOUGH DOCUMENTATION THAT SHOULD RESULT IN EITHER THE REPLACEMENT OF THESE UNITS OR FIND OUT WHAT THE PROBABLE CAUSE IS.

Data retrieved from NASA's ASRS site as of August 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.