Narrative:

On approach vectors for the ILS X to ZZZ at approximately 4000 ft MSL and on a 350 degree heading; winds 075 degrees at 5 KTS; 1800 ft broken; 10 mi visibility; over the northern coast of the island; we had a yellow master caution warning light illuminate and a yellow chip indication light on the engine instrument system. We were instructed shortly thereafter to continue our descent to 2000 ft. I asked ATC for an immediate short vector to final since we were east of the field and on delaying vectors for sequence; and ATC was only able to give me a slight left turn. These vectors would have brought us north of ZZZ VOR and then would have had to turn southwest and fly past the airport again to line up for the ILS X. My first officer and I monitored all engine parameters and did not see anything abnormal. We ran the checklist for the eis chip light under engine emergencys in the QRH. Being at such a low altitude and going out over the island sound; having a possible engine failure was hazardous in my opinion; especially having only 1 engine; and the checklist instructions were to land as soon as practical. Since ATC was unable to accommodate us going directly to the field under these circumstances; I felt in the interest of safety it was best for me to exercise emergency authority/authorized. We requested a lower altitude and were given 1500 ft MVA for that area; and headed straight into runway xx for a visual approach. This action minimized our time aloft and brought us to a safe landing much faster. On short final; the chip light extinguished; and we landed without incident on runway xx. After shutdown; I escorted our passenger; called operations; and informed the chief pilot and maintenance of the event. I also spoke with the airport authority/authorized and explained what happened. In addition; I wrote up the discrepancy in the aircraft flight log; and recommended that the aircraft not be flown again until the engine was inspected; which is noted in the last part of the QRH checklist. Under the circumstances; I believe my first officer and I made the right choices and put safety first instead of assuming it was a false warning.

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Original NASA ASRS Text

Title: UPON ENCOUNTERING YELLOW CHIP INDICATION AND MASTER WARNING LIGHTS; FLT CREW OF PC12 REQUEST EXPEDITED HANDLING AND THEN DECLARE AN EMERGENCY TO PROCEED IMMEDIATELY TO DES.

Narrative: ON APCH VECTORS FOR THE ILS X TO ZZZ AT APPROX 4000 FT MSL AND ON A 350 DEG HDG; WINDS 075 DEGS AT 5 KTS; 1800 FT BROKEN; 10 MI VISIBILITY; OVER THE NORTHERN COAST OF THE ISLAND; WE HAD A YELLOW MASTER CAUTION WARNING LIGHT ILLUMINATE AND A YELLOW CHIP INDICATION LIGHT ON THE ENG INST SYS. WE WERE INSTRUCTED SHORTLY THEREAFTER TO CONTINUE OUR DSCNT TO 2000 FT. I ASKED ATC FOR AN IMMEDIATE SHORT VECTOR TO FINAL SINCE WE WERE E OF THE FIELD AND ON DELAYING VECTORS FOR SEQUENCE; AND ATC WAS ONLY ABLE TO GIVE ME A SLIGHT L TURN. THESE VECTORS WOULD HAVE BROUGHT US N OF ZZZ VOR AND THEN WOULD HAVE HAD TO TURN SW AND FLY PAST THE ARPT AGAIN TO LINE UP FOR THE ILS X. MY FO AND I MONITORED ALL ENG PARAMETERS AND DID NOT SEE ANYTHING ABNORMAL. WE RAN THE CHKLIST FOR THE EIS CHIP LIGHT UNDER ENG EMERS IN THE QRH. BEING AT SUCH A LOW ALT AND GOING OUT OVER THE ISLAND SOUND; HAVING A POSSIBLE ENG FAILURE WAS HAZARDOUS IN MY OPINION; ESPECIALLY HAVING ONLY 1 ENG; AND THE CHKLIST INSTRUCTIONS WERE TO LAND AS SOON AS PRACTICAL. SINCE ATC WAS UNABLE TO ACCOMMODATE US GOING DIRECTLY TO THE FIELD UNDER THESE CIRCUMSTANCES; I FELT IN THE INTEREST OF SAFETY IT WAS BEST FOR ME TO EXERCISE EMER AUTH. WE REQUESTED A LOWER ALT AND WERE GIVEN 1500 FT MVA FOR THAT AREA; AND HEADED STRAIGHT INTO RWY XX FOR A VISUAL APCH. THIS ACTION MINIMIZED OUR TIME ALOFT AND BROUGHT US TO A SAFE LNDG MUCH FASTER. ON SHORT FINAL; THE CHIP LIGHT EXTINGUISHED; AND WE LANDED WITHOUT INCIDENT ON RWY XX. AFTER SHUTDOWN; I ESCORTED OUR PAX; CALLED OPS; AND INFORMED THE CHIEF PLT AND MAINT OF THE EVENT. I ALSO SPOKE WITH THE ARPT AUTH AND EXPLAINED WHAT HAPPENED. IN ADDITION; I WROTE UP THE DISCREPANCY IN THE ACFT FLT LOG; AND RECOMMENDED THAT THE ACFT NOT BE FLOWN AGAIN UNTIL THE ENG WAS INSPECTED; WHICH IS NOTED IN THE LAST PART OF THE QRH CHKLIST. UNDER THE CIRCUMSTANCES; I BELIEVE MY FO AND I MADE THE RIGHT CHOICES AND PUT SAFETY FIRST INSTEAD OF ASSUMING IT WAS A FALSE WARNING.

Data retrieved from NASA's ASRS site as of May 2009 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.