AFTER AN UNSAFE GEAR INDICATION ON FINAL APCH; RPTR PLT DID A GAR; TROUBLE-SHOT; GOT A GOOD GEAR DOWN INDICATION; HAD IT CHKED BY TWR ON A FLY-BY AND LANDED UNEVENTFULLY. CAUSED BY BAD MICRO SWITCH THAT HAD A HIGHER THAN NORMAL CONTACT RESISTANCE.

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THE PROB OCCURRED WHILE I WAS ON AN ILS APCH IN VMC CONDITIONS INTO BDL; CT; ON APR/XX/96. AS I CROSSED THE OM AND ACTUATED THE LNDG GEAR SWITCH; I NOTED THAT THE NORMAL 3 GREEN LIGHTS DID NOT APPEAR. AT THE TIME THERE WAS ENOUGH TURB TO CAUSE ME TO BE UNCERTAIN AS TO WHETHER THE GEAR HAD DSNDED OR NOT. AND AS IT IS NOT POSSIBLE TO OBSERVE THE GEAR CONDITION FROM THE COCKPIT OF THE PIPER MALIBU; I INFORMED THE TWR OF MY PROB AND REQUESTED THAT I BREAK OFF THE APCH; LEAVE THE AREA AND CIRCLE OUTSIDE THE CTL ZONE TO TRY TO ASCERTAIN THE PROB. THIS WAS APPROVED AND I WAS HANDED BACK TO APCH CTL. WHILE CIRCLING IN THE DESIGNATED AREA; I PULLED AND RESET THE CIRCUIT BREAKERS AND FOLLOWED OTHER EMER PROCS IN THE POH; INCLUDING RECYCLING THE LNDG GEAR; AT WHICH POINT THE GEAR INDICATOR LIGHTS RETURNED AND INDICATED A NORMAL GEAR DOWN POS. I THEN REQUESTED A FLYBY OF THE TWR TO CONFIRM THIS; WHICH WAS APPROVED; AND BOTH TWR AND GND PERSONNEL RPTED THAT THE GEAR APPEARED TO BE DOWN AND LOCKED. I WAS THEN CLRED TO LAND AND THE LNDG WAS UNEVENTFUL; ALTHOUGH I WAS FOLLOWED BY THE CRASH EQUIP AFTER TOUCHDOWN AND DURING THE ROLLOUT. I SUBSEQUENTLY HAD THE PLANE JACKED UP AND THE GEAR SWUNG AT AN AUTH PIPER MALIBU MAINT FACILITY; AND THEY DETERMINED THAT A MICROSWITCH IN THE GEAR CIRCUITRY HAD A HIGHER THAN NORMAL CONTACT RESISTANCE; RESULTING IN AN INTERMITTENT FAILURE MODE. THE SWITCH ASSEMBLY WAS REPLACED WITH A PROPERLY FUNCTIONING UNIT; AND THE GEAR RECYCLED A NUMBER OF TIMES WITH NO FURTHER PROBS. THE PROB HAS NOT REOCCURRED IN A FURTHER 40 HRS OF FLT TIME. A FAILURE OF THIS TYPE IS NOT READILY PREVENTED BY ROUTINE MAINT; AS THE SWITCH IN QUESTION HAS A VERY LOW FAILURE RATE AND IS NOT NORMALLY INSPECTED. IN THIS CASE IT HAD NOT ACTUALLY FAILED BUT WAS INTERMITTENT. IT IS EVEN MORE DIFFICULT WHEN THE FAILURE IS INTERMITTENT; AND ONLY A GOOD DIAGNOSTIC TECHNICIAN WAS ABLE TO FIND THE FAULT AFTER SEVERAL HRS OF TROUBLE-SHOOTING.