Small aircraft makes extreme turn when autoplt engaged. Disconnect, then HSI fails.

Attributes
ACN	198076
Time
Date	199112
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : rdg
State Reference	PA
Altitude	msl bound lower : 1500 msl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : rdg
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	climbout : initial climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument
Experience	flight time last 90 days : 40 flight time total : 500 flight time type : 350
ASRS Report	198076
Person 2
Affiliation	government : faa
Function	controller : departure
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather
Independent Detector	other other : unspecified cockpit
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

After takeoff in heavy rain on dec/xx/91 at about XA00 am local, we were at approximately 1500 ft MSL when I engaged the autoplt during climb out. When the autoplt engaged the plane went into a 45 degree and left hand bank. I immediately disengaged the autoplt. At that time we lost our HSI. At that point we continued to climb but had only the attitude indicator and turn and bank. The tower suggested we level at 300 MSL which we did and we continued to fly with a compass. After the tower gave us a timed turn during automatic I checked all the breakers and although it did not seem like we had a problem there the HSI returned to operation. At that point we returned to course and continued the flight. The only recurrence was an incorrect reading on the obs per boston center however after switching to albany it appeared that our obs was functioning properly. Although we did not use the autoplt anymore that day, I did try it several days later on the return flight. It seemed to work ok. Our observation was that it might have been a water problem as before takeoff several days later all trim controls were frozen solid with water and required extensive preheat to make the plane flyable.

Original NASA ASRS Text

Title: SMA MAKES EXTREME TURN WHEN AUTOPLT ENGAGED. DISCONNECT, THEN HSI FAILS.

Narrative: AFTER TKOF IN HVY RAIN ON DEC/XX/91 AT ABOUT XA00 AM LCL, WE WERE AT APPROX 1500 FT MSL WHEN I ENGAGED THE AUTOPLT DURING CLBOUT. WHEN THE AUTOPLT ENGAGED THE PLANE WENT INTO A 45 DEG AND L HAND BANK. I IMMEDIATELY DISENGAGED THE AUTOPLT. AT THAT TIME WE LOST OUR HSI. AT THAT POINT WE CONTINUED TO CLB BUT HAD ONLY THE ATTITUDE INDICATOR AND TURN AND BANK. THE TWR SUGGESTED WE LEVEL AT 300 MSL WHICH WE DID AND WE CONTINUED TO FLY WITH A COMPASS. AFTER THE TWR GAVE US A TIMED TURN DURING AUTO I CHKED ALL THE BREAKERS AND ALTHOUGH IT DID NOT SEEM LIKE WE HAD A PROBLEM THERE THE HSI RETURNED TO OP. AT THAT POINT WE RETURNED TO COURSE AND CONTINUED THE FLT. THE ONLY RECURRENCE WAS AN INCORRECT READING ON THE OBS PER BOSTON CENTER HOWEVER AFTER SWITCHING TO ALBANY IT APPEARED THAT OUR OBS WAS FUNCTIONING PROPERLY. ALTHOUGH WE DID NOT USE THE AUTOPLT ANYMORE THAT DAY, I DID TRY IT SEVERAL DAYS LATER ON THE RETURN FLT. IT SEEMED TO WORK OK. OUR OBSERVATION WAS THAT IT MIGHT HAVE BEEN A WATER PROBLEM AS BEFORE TKOF SEVERAL DAYS LATER ALL TRIM CTLS WERE FROZEN SOLID WITH WATER AND REQUIRED EXTENSIVE PREHEAT TO MAKE THE PLANE FLYABLE.

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.