A CPR BE9L-E PLT MADE AN ERRATIC APCH TO AUS; CAUSING THE CTLR TO QUESTION HIM UPON LNDG.

Narrative

I WAS IN SOLID IFR AT 14000 FT; STAYING UNDER THE FREEZING LEVEL IN A BEECH KING AIR C90-A EQUIPPED WITH DUAL KING KNR 634A NAVS #1 AND #3); KING KNS-81 RNAV (#2) AND IFR CERTIFIED GARMIN 155 GPS WITH #1; #2 AND GPS CAPABLE OF BEING COUPLED TO THE KFC-250 AUTOPLT. DUAL HSI'S; RADIO ALTIMETER PLUS STANDARD DUAL INSTRUMENTATION WERE ALSO INSTALLED. ANTICIPATING THAT IT MIGHT NOT BE POSSIBLE TO MAKE A VFR APCH INTO HORSESHOE BAY; I INSTRUCTED MY PAX TO ARRIVE 30 MINS EARLY IN CASE OF A DIVERSION TO AUSTIN. WHILE ENRTE; I DETERMINED THAT THE ENTIRE AREA OF EAST AND CENTRAL TEXAS WAS IFR. SO; AFTER BEING HANDED OFF TO ZHU N OF AUSTIN; I REQUESTED A CHANGE OF DEST TO AUSTIN/BERGSTROM (AUS) AND RECEIVED A CLRNC VIA DIRECT. UPON RECEIVING A HDOF TO AUSTIN APCH; I WAS TOLD TO EXPECT AN ILS TO RWY 17L. I THEN TUNED THE #1 NAV; WHICH DRIVES THE PLT SIDE HSI; TO 110.5 AND IMMEDIATELY PICKED UP DME ON THAT FREQ TO THE RWY 17L RWY; BUT RECEIVED NO LOC INDICATION ON THE HSI. I NOTICED THE GS INDICATOR WAS WORKING CORRECTLY SHOWING A FULL DEFLECTION DOWN AS I WAS WELL ABOVE THE GS AS I APCHED AUSTIN. I QUICKLY SWITCHED TO THE #2 NAV WHICH IS THE NS-81 AND PUT IT INTO THE VOR/ILS MODE. I CONTINUED TO RECEIVE GOOD DME AND GS INDICATIONS BUT NO LOC. THE #3 NAV DRIVES THE COPLT SIDE HSI AND I TURNED IT TO THE ILS 110.5 AND THERE WAS NO INDICATION HERE EITHER. I ADVISED THE APCH CTLR OF MY PROB AND ASKED FOR VECTORS TO THE LOC AND ASSISTANCE WITH DIRECTIONAL CTL SINCE I HAD GOOD DME AND GS. THE GARMIN 155 WAS AN ADD-ON AFTER THE AIRPLANE WAS BUILT AND MOUNTED VERTLY ON THE REAR SIDE OF THE CTR PEDESTAL. I SET IT TO THE AUSTIN DEST AND MONITORED THE INBOUND BEARING AND ATTEMPTED TO FLY THE LOC BEARING USING THIS FOR DIRECTION. I USED THE AUTOPLT DURING THIS PORTION OF THE APCH AND SET SPD AND LOWERED THE LNDG GEAR WHEN INTERCEPTING THE GS. HOWEVER; IT IS NOT POSSIBLE IN THIS AIRPLANE TO ALLOW THE AUTOPLT TO TRACK THE GPS AND STILL DISPLAY GS AND DME SIMULTANEOUSLY; SO I SPLIT MY ATTN BTWN THE HSI AND GPS. POSSIBLY DUE TO WIND; THE CTLR TOLD ME I WAS GOING R OF COURSE AND SUGGESTED I ABORT THE APCH; WHICH I DID. HE GAVE ME RADAR VECTORS AND AN ALT TO CLB TO; WHICH I FOLLOWED; AND HE ASKED MY INTENTIONS. AFTER AS QUICKLY AS POSSIBLE ANALYZING THAT THERE WAS NOT LIKELY ANY ARPT WITHIN 200 MI WITH A CEILING HIGH ENOUGH FOR A NON PRECISION APCH; I REQUESTED VECTORS FOR ANOTHER ATTEMPT FOR RWY 17L AT AUSTIN. ALSO; ONE OF MY PAX HAD BECOME AIRSICK AND THROWN UP IN THE WASTE BASKET AND ANOTHER HAD VERTIGO. THERE WAS OTHER AIRLINE TFC THAT THE CTLR WAS WORKING; SO HE VECTORED ME OUT FOR ANOTHER ATTEMPT AND CLRED ME FOR THE GPS RWY 17L APCH. DUE TO THE NATURE OF PROGRAMMING IN THE GARMIN 155; IN ORDER TO SET UP A GPS APCH REQUIRES SEVERAL STEPS. IT IS IDEAL FOR AN APCH PLANNED WELL IN ADVANCE. DUE TO OTHER TFC AND THE CTLR'S WORKLOAD; AS WELL AS MINE; I DIDN'T HAVE TIME TO SET UP THE GPS INTO THE APCH MODE AND CONTINUED TO USE THE RAW BEARING INFO FOR THE SECOND ATTEMPT. AGAIN I SET SPD; FLAPS AND GEAR AND SET A DSCNT FOR THE GS. THE CTLR ADVISED I WAS R OF COURSE AND I MADE A SLIGHT CORRECTION L ASSUMING THE L QUARTERING XWIND WAS AFFECTING MY GND TRACK. AGAIN HE TOLD ME I WAS R OF COURSE AND I CORRECTED SLIGHTLY AGAIN. MAYBE HE MADE A MISTAKE IN SAYING I WAS TO THE R OF THE LOC OR MAYBE I MISUNDERSTOOD AND HE WAS SAYING THE LOC WAS TO MY R. THE PUBLISHED MINIMUM IS 469 FT AGL. AT ABOUT 600 FT AGL ON MY RADAR ALTIMETER; WHICH READS OUT ADJACENT TO MY DME; I WAS IN AN OPENING OF THE CLOUDS AND HAD CLR VIEW OF THE GND. THE RAIN HAD ENDED AND INFLT VISIBILITY WAS AT LEAST 3 MI WHEN CLR OF THE CLOUDS. I RPTED GND IN SIGHT AND IT TOOK A SECOND OR TWO TO REALIZE THAT THE RWY WAS WELL TO MY R. I CALLED 'RWY IN SIGHT' AND ASKED FOR A LNDG ON RWY 35 SINCE I WAS AN ESTIMATED 3000 FT TO THE L OF CTRLINE. HE SAID THAT WAS NOT POSSIBLE AND I THEN AGREED TO ACCEPT RWY 17L AND HE TOLD ME TO CONTACT THE TWR. I MADE A QUICK R TURN AND THEN A L TO LINE UP WITH THE RWY. THE TWR CLRED ME TO LAND AND I DID SO AT ABOUT THE NORMAL TOUCHDOWN POINT AT NORMAL APCH SPD ON THE 9000 FT RWY. TO THE BEST OF MY KNOWLEDGE; I CALLED THE RWY IN SIGHT BEFORE I REACHED PUBLISHED MINIMUMS. THIS IS AN ARPT THAT I HAVE BEEN FLYING INTO SINCE IT OPENED AS A CIVILIAN FIELD AND YRS BEFORE IN THE AIR FORCE. UPON REACHING THE FBO FUEL DESK; THE ATTENDANT WAS ON THE PHONE AND ASKED ME IF I WAS FLYING AND I RPTED I WAS. SHE SAID THE TWR WAS ON THE PHONE. I TALKED TO A CTLR IN THE TWR AND SHE SAID SHE WAS CONCERNED ABOUT MY ERRATIC APCH. I EXPLAINED MY TRIPLE FAILURE OF LOC INFO AND; DUE TO THE WIDE AREA OF IFR WX; ELECTED TO MAKE THE SECOND ATTEMPT FROM WHICH I LANDED. I DON'T RECALL ANY FURTHER COMMENT; OTHER THAN SHE WAS CONCERNED ABOUT MY ABNORMAL APCH. UNDER THE CIRCUMSTANCES; WITH WX OVER SUCH A WIDE AREA; AND THE FACT THAT I HAD EXCELLENT VISIBILITY AFTER CLRING THE CLOUDS; I DO NOT FEEL THAT I BROKE ANY MINIMUMS NOR DID ANY UNSAFE MANEUVERS. I WILL ADMIT THAT THIS WAS NOT AN IDEAL SIT AND ONE THAT I WOULD NOT NORMALLY HAVE ATTEMPTED HAD THERE BEEN A SUITABLE ALTERNATE WITHIN A REASONABLE DISTANCE. PRIOR TO SHUTTING DOWN THE ACFT; I RETRIED ALL 3 NAVS AND FOUND THEM STILL GIVING NO L/R NEEDLE DEFLECTION TO THE HSI. AFTER MY QUEASY PAX LEFT; I CONTACTED A RADIO REPAIRMAN TO CHK OUT THE PROB. HE WAS BUSY AND COULD NOT LEAVE FOR 3 HRS. IN THE MEANTIME; I HAD THE ACFT REFUELED. WHEN THE RADIO MAN ARRIVED AND PLACED HIS TEST XMITTER IN THE ACFT; BOTH #1 AND #2 NAVS GAVE A FULL AND STEADY NORMAL DEFLECTION. I FEEL THAT THE 1 HR FLT IN LIGHT TO MODERATE RAIN CREATED A CERTAIN AMOUNT OF P-STATIC THAT AFFECTED THE NAV ANTENNAE IN THE 110.5 MHZ FREQ RANGE. WHEN THE REFUELING TRUCK GNDED THE ACFT; THE STATIC ELECTRIC HAD DISSIPATED; PROBABLY RETURNING THE ANTENNAE TO NORMAL. THE REPAIR MAN ALSO AGREED THAT THIS WAS A PROBABLE CAUSE. THIS AIRPLANE WAS REPAINTED 12 MONTHS PRIOR TO THIS FLT JUST BEFORE FLT. I RECALL ONE OTHER INSTANCE OF A MOMENTARY LOSS OF LOC SIGNAL WHILE PASSING THROUGH A LIGHT SHOWER TOWARD A VISUAL INTERCEPT TO A LOC AT MCALLEN; BUT THOUGHT NOTHING OF IT SINCE IT LASTED ONLY A SECOND OR TWO AND THE ARPT WAS VFR.