Narrative:

After a normal preflight and departure we were assigned 6000 ft as a final. The WX was a mix of moderate rain and snow, temperature was holding about +1 degree C, so the watch for ice conditions was being paid strict attention. After 15-20 mins in cruise, the right engine fire warning light illuminated and as it does normally, activated the master warning lights on the pilot/copilot glareshields. Both pilots immediately looked at the right engine to see if there was any evidence of fire. I saw none, but asked the first officer to continue to watch it since he had a much better view. I began scanning engine instruments to look for any abnormalities. No abnormalities were found and neither engine showed signs of fire, so the decision was made to leave the engine running unless something indicated a need for shutdown. At this time, because the problem was unclr, the crew discussed options for the remainder of the flight. Our original destination was 15 mins flight time, 2 other airports hpn and dxr were under 10 mins flight time. I advised ATC we wished to divert to hpn and I advised them of the problem. I did not then or at any time declare an emergency. Approach gave me the WX at hpn and because of the situation, I discussed the WX with the first officer and then advised ATC we would then like to continue to our original destination (teb). WX was 300 ft 1 mi visibility at hpn, just at minimums, 900 ft 4 mi at teb, well above minimums. The controller offered dxr, which was 700 ft 2 mi visibility, I advised that due to terrain and WX we would continue to teb. The need to deal with only 1 problem, the fire light, and not the WX and terrain, made teb seem like a better option. All indications remained normal throughout the approach. We did request no delay into teb and also asked for crash fire rescue equipment just in case something occurred on the landing. The aircraft was landed without incident and no fire occurred. Investigation into the problem revealed very little as to what the cause for the fault may have been. No evidence of fire was found and all system tested normally. I caution king air pilots who are inclined to minimize fire warning lights because the sun or the precipitation sets them off on occasion. This was a serious system malfunction that may have disabled the system if left to go long enough. As far as the priority handling and fire trucks, better safe than sorry. Callback conversation with reporter revealed the following information: reporter stated that this aircraft has a known equipment design problem in the fire warning system. The sun or rain can set this alarm system off. The aircraft checklist says to change aircraft's heading if exposed to the sun so as to adjust the reflective lighting effect. Because of this checklist reporter says the manufacturer must know of the problem. In addition, there are king airs that have had a modified continuous loop sensor system installed where the alarm is set off only when the current is broken. This aircraft did not have that new system. He further stated that there are thousands (?) of king airs out there, with or without the new system. There had been one airworthiness directive put out for an infrared sensor change but he didn't think it was on the 200 series king air.

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Original NASA ASRS Text

Title: BE20 CPR FLC NOTE A FIRE WARNING ON #2 ENG WHILE IN IMC FLT. AFTER DECIDING AGAINST AN INFLT DIVERSION TO ALTERNATE ACCOUNT ENRTE WX, THEY ELECT TO CONTINUE TO DEST, TEB ARPT.

Narrative: AFTER A NORMAL PREFLT AND DEP WE WERE ASSIGNED 6000 FT AS A FINAL. THE WX WAS A MIX OF MODERATE RAIN AND SNOW, TEMP WAS HOLDING ABOUT +1 DEG C, SO THE WATCH FOR ICE CONDITIONS WAS BEING PAID STRICT ATTN. AFTER 15-20 MINS IN CRUISE, THE R ENG FIRE WARNING LIGHT ILLUMINATED AND AS IT DOES NORMALLY, ACTIVATED THE MASTER WARNING LIGHTS ON THE PLT/COPLT GLARESHIELDS. BOTH PLTS IMMEDIATELY LOOKED AT THE R ENG TO SEE IF THERE WAS ANY EVIDENCE OF FIRE. I SAW NONE, BUT ASKED THE FO TO CONTINUE TO WATCH IT SINCE HE HAD A MUCH BETTER VIEW. I BEGAN SCANNING ENG INSTS TO LOOK FOR ANY ABNORMALITIES. NO ABNORMALITIES WERE FOUND AND NEITHER ENG SHOWED SIGNS OF FIRE, SO THE DECISION WAS MADE TO LEAVE THE ENG RUNNING UNLESS SOMETHING INDICATED A NEED FOR SHUTDOWN. AT THIS TIME, BECAUSE THE PROB WAS UNCLR, THE CREW DISCUSSED OPTIONS FOR THE REMAINDER OF THE FLT. OUR ORIGINAL DEST WAS 15 MINS FLT TIME, 2 OTHER ARPTS HPN AND DXR WERE UNDER 10 MINS FLT TIME. I ADVISED ATC WE WISHED TO DIVERT TO HPN AND I ADVISED THEM OF THE PROB. I DID NOT THEN OR AT ANY TIME DECLARE AN EMER. APCH GAVE ME THE WX AT HPN AND BECAUSE OF THE SIT, I DISCUSSED THE WX WITH THE FO AND THEN ADVISED ATC WE WOULD THEN LIKE TO CONTINUE TO OUR ORIGINAL DEST (TEB). WX WAS 300 FT 1 MI VISIBILITY AT HPN, JUST AT MINIMUMS, 900 FT 4 MI AT TEB, WELL ABOVE MINIMUMS. THE CTLR OFFERED DXR, WHICH WAS 700 FT 2 MI VISIBILITY, I ADVISED THAT DUE TO TERRAIN AND WX WE WOULD CONTINUE TO TEB. THE NEED TO DEAL WITH ONLY 1 PROB, THE FIRE LIGHT, AND NOT THE WX AND TERRAIN, MADE TEB SEEM LIKE A BETTER OPTION. ALL INDICATIONS REMAINED NORMAL THROUGHOUT THE APCH. WE DID REQUEST NO DELAY INTO TEB AND ALSO ASKED FOR CFR JUST IN CASE SOMETHING OCCURRED ON THE LNDG. THE ACFT WAS LANDED WITHOUT INCIDENT AND NO FIRE OCCURRED. INVESTIGATION INTO THE PROB REVEALED VERY LITTLE AS TO WHAT THE CAUSE FOR THE FAULT MAY HAVE BEEN. NO EVIDENCE OF FIRE WAS FOUND AND ALL SYS TESTED NORMALLY. I CAUTION KING AIR PLTS WHO ARE INCLINED TO MINIMIZE FIRE WARNING LIGHTS BECAUSE THE SUN OR THE PRECIP SETS THEM OFF ON OCCASION. THIS WAS A SERIOUS SYS MALFUNCTION THAT MAY HAVE DISABLED THE SYS IF LEFT TO GO LONG ENOUGH. AS FAR AS THE PRIORITY HANDLING AND FIRE TRUCKS, BETTER SAFE THAN SORRY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THIS ACFT HAS A KNOWN EQUIP DESIGN PROB IN THE FIRE WARNING SYS. THE SUN OR RAIN CAN SET THIS ALARM SYS OFF. THE ACFT CHKLIST SAYS TO CHANGE ACFT'S HDG IF EXPOSED TO THE SUN SO AS TO ADJUST THE REFLECTIVE LIGHTING EFFECT. BECAUSE OF THIS CHKLIST RPTR SAYS THE MANUFACTURER MUST KNOW OF THE PROB. IN ADDITION, THERE ARE KING AIRS THAT HAVE HAD A MODIFIED CONTINUOUS LOOP SENSOR SYS INSTALLED WHERE THE ALARM IS SET OFF ONLY WHEN THE CURRENT IS BROKEN. THIS ACFT DID NOT HAVE THAT NEW SYS. HE FURTHER STATED THAT THERE ARE THOUSANDS (?) OF KING AIRS OUT THERE, WITH OR WITHOUT THE NEW SYS. THERE HAD BEEN ONE AIRWORTHINESS DIRECTIVE PUT OUT FOR AN INFRARED SENSOR CHANGE BUT HE DIDN'T THINK IT WAS ON THE 200 SERIES KING AIR.

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