Narrative:

On downwind to bos runway 22R I put gear down and got an unsafe on the right main gear. I told tower of the situation and he asked my intention. I told him that I believe it was a warning problem and that the gear was probably down, and that I would land on 22R and to call the equipment to the runway. I cycled the gear twice and the lights did not change. The gear is mechanical with rod to each gear and you can hear the gear lock in, plus a rod would have to break before it would not lock. The micro switches get ice or dirt on them and they will not indicate correctly. This has happened to me before so I was pretty sure it was a micro switch that got dirty or ice on it. When I touched down the right gear light turned green. I told the tower everything was ok, taxied to the runway, checked the gear--it was locked and the micro switch had some ice on it. I cleaned it off, moved the switch, it was frozen, so I returned to airport in nj (ron). Flew to home base next day and had mechanic check out gear. Report was the gear was ok. Adjustments were right on, could not find anything wrong with the gear. Also, the mechanic agreed with me that it was ice on the micro switch. If it was daylight I would have asked the tower for a fly by. I think that knowing the aircraft that you are flying is what made the difference in my action.

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Original NASA ASRS Text

Title: CORP SMT UNABLE TO GET SAFE INDICATION ON MAIN LNDG GEAR. EMERGENCY CRASH EQUIPMENT ACTIVATED.

Narrative: ON DOWNWIND TO BOS RWY 22R I PUT GEAR DOWN AND GOT AN UNSAFE ON THE RIGHT MAIN GEAR. I TOLD TWR OF THE SITUATION AND HE ASKED MY INTENTION. I TOLD HIM THAT I BELIEVE IT WAS A WARNING PROB AND THAT THE GEAR WAS PROBABLY DOWN, AND THAT I WOULD LAND ON 22R AND TO CALL THE EQUIP TO THE RWY. I CYCLED THE GEAR TWICE AND THE LIGHTS DID NOT CHANGE. THE GEAR IS MECHANICAL WITH ROD TO EACH GEAR AND YOU CAN HEAR THE GEAR LOCK IN, PLUS A ROD WOULD HAVE TO BREAK BEFORE IT WOULD NOT LOCK. THE MICRO SWITCHES GET ICE OR DIRT ON THEM AND THEY WILL NOT INDICATE CORRECTLY. THIS HAS HAPPENED TO ME BEFORE SO I WAS PRETTY SURE IT WAS A MICRO SWITCH THAT GOT DIRTY OR ICE ON IT. WHEN I TOUCHED DOWN THE RIGHT GEAR LIGHT TURNED GREEN. I TOLD THE TWR EVERYTHING WAS OK, TAXIED TO THE RWY, CHKED THE GEAR--IT WAS LOCKED AND THE MICRO SWITCH HAD SOME ICE ON IT. I CLEANED IT OFF, MOVED THE SWITCH, IT WAS FROZEN, SO I RETURNED TO ARPT IN NJ (RON). FLEW TO HOME BASE NEXT DAY AND HAD MECHANIC CHK OUT GEAR. RPT WAS THE GEAR WAS OK. ADJUSTMENTS WERE RIGHT ON, COULD NOT FIND ANYTHING WRONG WITH THE GEAR. ALSO, THE MECHANIC AGREED WITH ME THAT IT WAS ICE ON THE MICRO SWITCH. IF IT WAS DAYLIGHT I WOULD HAVE ASKED THE TWR FOR A FLY BY. I THINK THAT KNOWING THE ACFT THAT YOU ARE FLYING IS WHAT MADE THE DIFFERENCE IN MY ACTION.

Data retrieved from NASA's ASRS site as of August 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.