Small aircraft has gyroscope failure. Makes ILS approach with no gyroscope.

Attributes
ACN	202937
Time
Date	199202
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ugn
State Reference	IL
Altitude	msl bound lower : 2000 msl bound upper : 3000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tower : ugn
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	descent : approach descent other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 25 flight time total : 700 flight time type : 200
ASRS Report	202937
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : critical other anomaly other other spatial deviation
Independent Detector	other other : unspecified cockpit
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Departed bfa on IFR flight plan noticed gyroscope failure due to lack of accurate tracking of autoplt. Reported gyroscope failure to center. I was in VFR conditions on top en route and reported WX was improving towards destination so flight was continued without event. Cloud layer was overcast - 1000 ft thick. Was established on ILS in VFR conditions for letdown. I was switched to tower frequency during descent, I was approximately 1/2 mi south of localizer - had full scale deflection on ILS but as I knew I would be VFR in 100-200 ft well above terrain and MDA continued approach with a correction to north. Broke out about 500 ft above MDA/DH on 2 mi final. Tower informed me approach had called them to say I was off ILS. Told tower I was VFR now and had gyroscope failure to explain deviation from course and not missing approach. My last practice with partial panel was about 1 1/2 yrs ago at time of wings phase I program. Although directional gyroscope and vacuum pump were less than a yr old and plane has standby vacuum system, partial panel practice needs to be done more frequently.

Original NASA ASRS Text

Title: SMA HAS GYROSCOPE FAILURE. MAKES ILS APCH WITH NO GYROSCOPE.

Narrative: DEPARTED BFA ON IFR FLT PLAN NOTICED GYROSCOPE FAILURE DUE TO LACK OF ACCURATE TRACKING OF AUTOPLT. RPTED GYROSCOPE FAILURE TO CTR. I WAS IN VFR CONDITIONS ON TOP ENRTE AND RPTED WX WAS IMPROVING TOWARDS DEST SO FLT WAS CONTINUED WITHOUT EVENT. CLOUD LAYER WAS OVERCAST - 1000 FT THICK. WAS ESTABLISHED ON ILS IN VFR CONDITIONS FOR LETDOWN. I WAS SWITCHED TO TWR FREQ DURING DSCNT, I WAS APPROX 1/2 MI S OF LOC - HAD FULL SCALE DEFLECTION ON ILS BUT AS I KNEW I WOULD BE VFR IN 100-200 FT WELL ABOVE TERRAIN AND MDA CONTINUED APCH WITH A CORRECTION TO N. BROKE OUT ABOUT 500 FT ABOVE MDA/DH ON 2 MI FINAL. TWR INFORMED ME APCH HAD CALLED THEM TO SAY I WAS OFF ILS. TOLD TWR I WAS VFR NOW AND HAD GYROSCOPE FAILURE TO EXPLAIN DEV FROM COURSE AND NOT MISSING APCH. MY LAST PRACTICE WITH PARTIAL PANEL WAS ABOUT 1 1/2 YRS AGO AT TIME OF WINGS PHASE I PROGRAM. ALTHOUGH DIRECTIONAL GYROSCOPE AND VACUUM PUMP WERE LESS THAN A YR OLD AND PLANE HAS STANDBY VACUUM SYS, PARTIAL PANEL PRACTICE NEEDS TO BE DONE MORE FREQUENTLY.

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.