Narrative:

Aircraft 'a' was scheduled approximately jul/sun/01. I flew aircraft a on jul/sun/01 and confirmed that all instruments were ok for the IFR environment and that is why I requested it on jul/fri/01 for the flight on jul/thu/01. On the morning of jul/tue/01, the ceilings were approximately 1000 ft broken with visibility 6-7 mi. I filed IFR for frg-bdr-frg. Upon arrival at the FBO, I was informed that I had been changed to aircraft B. I then had to refile the plan. I had squawked the directional gyro on that aircraft on apr/fri/01. I asked if there were any outstanding squawks and was told that there were none. After preflight, I received the IFR release approximately XA30. I was to be radar vectored to bdr for full stop lndgs. While en route to bdr, ATC advised that bdr was not accepting practice approachs and offered the ILS runway 24 at isp. I accepted their suggestion and they issued a clearance direct to CCC VOR. I had been resetting the directional gyro several times approaching the CCC VOR and requested a confirmation from ATC regarding my heading. Close to the VOR ATC began issuing vectors for intercepting the localizer for isp runway 24 and eventually the clearance for the approach. It was during this period that I noticed the erratic behavior of the directional gyro which hesitated while turning and then would skip ahead. I also encountered erratic behavior of the localizer needle and could not capture the localizer. I had received the localizer frequency code and it was correct. I tried to ignore the directional gyro and fly the localizer but that did not work. At around this same time period ATC advised that the transponder was not transmitting properly and suggested resetting. Upon reset, ATC responded that it was still faulty. It was during this period of trying to sort out the instrument problems that I had inadvertently descended below the published altitude for the approach. I immediately advised the isp tower that I would execute the missed approach. They issued the vectors and altitude for the missed approach. During this sequence ATC advised that I should call them upon my return to frg. I was vectored to the ILS runway 14 approach. I had the same erratic behavior of the instruments, however, the ceilings were high enough to see the airport and the runway, so I could proceed VFR with a circle to land on runway 19. At the FBO, I submitted a squawk sheet for the 3 instruments: 1) directional gyro erratic, 2) omni 1 (localizer) erratic, 3) transponder faulted by ATC).

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Original NASA ASRS Text

Title: PIPER PA28-161 PLT, WHILE PRACTICING AN ILS INST APCH, WANDERED OFF THE VECTOR HDG TO THE ILS AND DSNDED EARLY BELOW THE DECISION HT DUE TO MALFUNCTIONING DIRECTIONAL GYRO AND ILS LOC INDICATOR.

Narrative: ACFT 'A' WAS SCHEDULED APPROX JUL/SUN/01. I FLEW ACFT A ON JUL/SUN/01 AND CONFIRMED THAT ALL INSTS WERE OK FOR THE IFR ENVIRONMENT AND THAT IS WHY I REQUESTED IT ON JUL/FRI/01 FOR THE FLT ON JUL/THU/01. ON THE MORNING OF JUL/TUE/01, THE CEILINGS WERE APPROX 1000 FT BROKEN WITH VISIBILITY 6-7 MI. I FILED IFR FOR FRG-BDR-FRG. UPON ARR AT THE FBO, I WAS INFORMED THAT I HAD BEEN CHANGED TO ACFT B. I THEN HAD TO REFILE THE PLAN. I HAD SQUAWKED THE DIRECTIONAL GYRO ON THAT ACFT ON APR/FRI/01. I ASKED IF THERE WERE ANY OUTSTANDING SQUAWKS AND WAS TOLD THAT THERE WERE NONE. AFTER PREFLT, I RECEIVED THE IFR RELEASE APPROX XA30. I WAS TO BE RADAR VECTORED TO BDR FOR FULL STOP LNDGS. WHILE ENRTE TO BDR, ATC ADVISED THAT BDR WAS NOT ACCEPTING PRACTICE APCHS AND OFFERED THE ILS RWY 24 AT ISP. I ACCEPTED THEIR SUGGESTION AND THEY ISSUED A CLRNC DIRECT TO CCC VOR. I HAD BEEN RESETTING THE DIRECTIONAL GYRO SEVERAL TIMES APCHING THE CCC VOR AND REQUESTED A CONFIRMATION FROM ATC REGARDING MY HDG. CLOSE TO THE VOR ATC BEGAN ISSUING VECTORS FOR INTERCEPTING THE LOC FOR ISP RWY 24 AND EVENTUALLY THE CLRNC FOR THE APCH. IT WAS DURING THIS PERIOD THAT I NOTICED THE ERRATIC BEHAVIOR OF THE DIRECTIONAL GYRO WHICH HESITATED WHILE TURNING AND THEN WOULD SKIP AHEAD. I ALSO ENCOUNTERED ERRATIC BEHAVIOR OF THE LOC NEEDLE AND COULD NOT CAPTURE THE LOC. I HAD RECEIVED THE LOC FREQ CODE AND IT WAS CORRECT. I TRIED TO IGNORE THE DIRECTIONAL GYRO AND FLY THE LOC BUT THAT DID NOT WORK. AT AROUND THIS SAME TIME PERIOD ATC ADVISED THAT THE XPONDER WAS NOT XMITTING PROPERLY AND SUGGESTED RESETTING. UPON RESET, ATC RESPONDED THAT IT WAS STILL FAULTY. IT WAS DURING THIS PERIOD OF TRYING TO SORT OUT THE INST PROBS THAT I HAD INADVERTENTLY DSNDED BELOW THE PUBLISHED ALT FOR THE APCH. I IMMEDIATELY ADVISED THE ISP TWR THAT I WOULD EXECUTE THE MISSED APCH. THEY ISSUED THE VECTORS AND ALT FOR THE MISSED APCH. DURING THIS SEQUENCE ATC ADVISED THAT I SHOULD CALL THEM UPON MY RETURN TO FRG. I WAS VECTORED TO THE ILS RWY 14 APCH. I HAD THE SAME ERRATIC BEHAVIOR OF THE INSTS, HOWEVER, THE CEILINGS WERE HIGH ENOUGH TO SEE THE ARPT AND THE RWY, SO I COULD PROCEED VFR WITH A CIRCLE TO LAND ON RWY 19. AT THE FBO, I SUBMITTED A SQUAWK SHEET FOR THE 3 INSTS: 1) DIRECTIONAL GYRO ERRATIC, 2) OMNI 1 (LOC) ERRATIC, 3) XPONDER FAULTED BY ATC).

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.