HDG TRACK DEV MESSES UP AN IAP ILS APCH.

Narrative

WHILE FLYING WITH 2 PAX ON APR/FRI/94; I WAS CLRED FOR THE ILS RWY 18R APCH TO CHARLOTTE DOUGLAS FIELD IN CHARLOTTE; NC. WX CONDITIONS WERE EXTREME WITH SEVERE TURB; HVY RAIN; LIGHTNING; AND LARGE AMOUNTS OF UNCTLED ALT GAINS/LOSSES. AT THIS POINT; THE FLT HAD LASTED SOME 1/2 HR AND THE PAX TO MY R WAS BEING VIOLENTLY ILL TO HER STOMACH. AFTER MULTIPLE HDG CHANGE REQUESTS FROM APCH; I JOINED THE LOC AS INSTRUCTED AND WAS WAITING TO INTERCEPT THE GS WHEN I NOTED SEVERE DEFLECTION OF THE LOC NEEDLE. BELIEVING THE DEFLECTION WAS DUE TO THE HVY WINDS; I TURNED THE PLANE FURTHER TO REGAIN LOC INTERCEPTION. THIS CONTINUED TO OCCUR AND FINALLY I WAS NOTIFIED BY APCH THAT I WAS IN THE AREA OF TRANSGRESSION AND RECEIVED FURTHER COURSE DIRECTIONS FROM THEM. SHORTLY THEREAFTER; I WAS TOLD TO CLB IMMEDIATELY AND MAINTAIN A HDG OF 270 DEGS; WHICH I DID. JUST PRIOR TO THE TIME OF THIS INCIDENT; SEVERAL LARGE AIRPLANES HAD BROKEN OFF THE APCH AND ONE ASKED TO BE BROUGHT OUT 30 MI FOR A NEW APCH. ANOTHER INDICATED THEY WERE 'PAINTING RED' OVER THE END OF THE RWY. IN SPITE OF THIS; THERE WERE OTHER PLANES MAKING THE APCH. AFTER BEING VECTORED OUT OF THE AREA ON THE HDG OF 270 DEGS; I WAS BROUGHT BACK AROUND FOR AN APCH ON ILS RWY 18L. THIS APCH WAS EXECUTED NORMALLY AND WITHOUT INCIDENT; ALTHOUGH CONDITIONS WERE NOT QUITE AS SEVERE AS IN THE ATTEMPT ON THE RWY 18R APCH. UPON LNDG; I WAS ASKED TO CONTACT THE TWR SUPVR; WHICH I DID IMMEDIATELY. THE TWR SUPVR WANTED TO KNOW 'WHAT THE HECK HAD GONE ON UP THERE?' HE SAID AT ONE POINT THE RADAR INDICATED THAT I WAS TRACKING ALMOST DIRECTLY OPPOSITE THE CORRECT HDG FOR THE 18R APCH. I TOLD HIM THAT I WAS 'FLABBERGASTED' AT THAT COMMENT AND I COULD NOT UNDERSTAND HOW IT COULD HAVE HAPPENED. HE ASSURED ME IT DID HAPPEN AND I AGAIN TOLD HIM THAT I HAD NO EXPLANATION AND COULD NOT UNDERSTAND HOW THIS COULD OCCUR. I REMAINED PERPLEXED OVER THIS CHAIN OF EVENTS FOR THE REST OF THE AFTERNOON AND MOST OF THE EVENING; AND IT WASN'T UNTIL THE NEXT MORNING THAT I INADVERTENTLY DISCOVERED WHAT I BELIEVED TO BE THE CAUSE OF THE PROB. I DEPARTED DOUGLAS- CHARLOTTE THE NEXT MORNING IN VFR CONDITIONS. AFTER BEING GIVEN CLRNC FOR TKOF; I RESET MY DIRECTIONAL GYRO AS IS MY HABIT PRIOR TO EACH TKOF. AFTER TKOF; I WAS REQUESTED TO FLY A HDG OF 270 DEGS; WHICH I DID. DURING THIS CLBING TURN; I FOUND; TO MY GREAT AMAZEMENT THAT THE DIRECTIONAL GYRO STILL INDICATED 180 DEGS. I TURNED THE ADJUSTING KNOB TO SET THE DIRECTIONAL GYRO AND; THIS TIME; MANUALLY PULLED THE STEM ALL THE WAY OUT. THE GYRO FUNCTIONED NORMALLY. SHORTLY THEREAFTER; I WAS SUCCESSFUL IN MAKING THE ADJUSTING KNOB STICK IN THE 'IN' POS 2 OR 3 TIMES (OUT OF ABOUT 25 ATTEMPTS). FURTHER INSPECTION REVEALED THAT THE PLASTIC INST PANEL MASK HAD LOOSENED AT THE BOTTOM. THIS CONDITION CAUSED THE ADJUSTMENT KNOB OF THE DIRECTIONAL GYRO TO BECOME BOUND AND STUCK IN THE 'IN' POS; WHICH OBVIOUSLY RENDERED THE GYRO USELESS WHILE IT WAS IN THIS MODE. I BELIEVE I RESET THE GYRO UPON BECOMING INITIALLY ESTABLISHED ON THE LOC AND THAT THE ADJUSTED KNOB BECAME STUCK AT THIS POINT. THE KNOB THEN BECAME UNSTUCK DURING THE HVY TURB AND SEVERE MOVEMENT OF THE ACFT; AND DID NOT STICK AGAIN WHEN I NEXT SET THE GYRO. THE CONTRIBUTING FACTORS TO THE FAILURE OF THIS UNSTABILIZED APCH WERE: TEMPORARILY MALFUNCTIONING DIRECTIONAL GYRO; AND SEVERE WX CONDITIONS WHICH MADE ACFT CTL DIFFICULT. OBVIOUSLY; MY ATTN WAS SOMEWHAT DISTRACTED BY WX AND MY ILL PAX; BUT I DON'T KNOW THAT THE ABSENCE OF THESE FACTORS WOULD HAVE NECESSARILY LED TO DETECTION OF THE MALFUNCTIONING GYRO IN TIME TO STABILIZE THE APCH.