NON ADHERENCE TO ATC PROC DURING IAP NDB APCH.

Narrative

ON A DEADHEAD (FRY) LEG RETURNING TO HOME BASE I HAD RECEIVED THE FINAL ASSIGNED HDG TO INTERCEPT THE FINAL APCH FOR A STRAIGHT-IN NDB APCH. UPON TURNING FINAL THE CTLR TOLD ME TO SWITCH TO TWR FREQ. AT THAT MOMENT THE ADF NEEDLE QUICKLY BEGAN TO FALL AND I RPTED MY POS TO THE TWR AS BEING OVER THE FINAL APCH FIX. THE TWR THEN CLRED ME TO LAND AND I STARTED MY DSCNT TO MDA. I HAD DSNDED 200 FT WHEN I NOTICED MY ADF NEEDLE WAS NOW POINTING TOWARD THE NOSE OF THE AIRPLANE. I IMMEDIATELY LEVELED OFF AND THE TWR ADVISED ME TO CONTACT SEYMOUR JOHNSON APCH. THE APCH CTLR ADVISED ME I WAS L OF COURSE AND THAT THE MIN ALT WAS 2100 FT. HE GAVE ME A HDG TO REESTABLISH ME ON FINAL. I CLBED FROM 1900 TO 2100 AND WAS SWITCHED BACK TO TWR CTL. THIS TIME I HAD TRUE STATION PASSAGE AND STARTED MY DSCNT TO MDA AND COMPLETED THE APCH WITH NO FURTHER PROBLEMS. CONTRIBUTING FACTORS: ILS OTS. VOR AND DME WERE OTS. STATIC (WX-INDUCED) INTERFERENCE ON ADF NEEDLE. MANY THANKS TO THE HEADS-UP EFFORT OF SEYMOUR JOHNSON CTLRS. NICE TO KNOW THEY KEEP AN EYE ON THOSE IN THE SKY.