Narrative:

Upon leveling out at 15000', we had the engine fire/wheel well detector inoperative light illuminate. Our checklist and procedures for this, when it happens in conjunction with an engine failure, is to treat it as an engine fire; i.e., engine shutdown and exterior agent. There is no specific procedure when it comes on west/O an engine failure, so I opted to use the same procedure (shutdown, declare emergency, discharge bottle) for safety's sake. (Once the detector is inoperative, one doesn't know if one has a fire or not.) a catastrophic fire could instantly disable this kind of sensor circuit. The question has arisen from management whether this was a prudent course of action, considering no visible evidence of fire was noted. If we are to treat this situation as fire with engine failure, why should it be different west/O an engine failure? Don't most engine fires occur west/O an associated failure? With this particular type of engine cowling and location, you cannot be sure of no fire just be looking out the window. So the question I had to ask myself at the time was, do I just assume there is no problem and hope everything is ok and do nothing, or play it safe and treat it as an emergency? Keep in mind, it is drilled into us during training that a detector inoperative warning is to be treated as a fire (with an engine failure). Again, why should there be a difference west/O an engine failure? And if there is to be a difference, it is not spelled out in procedures. I felt I had acted in the safest manner, considering it was cavu and the airport was in sight. We landed west/O incident. Another thought process was, if I didn't do anything and there was a situation that worsened, who would I answer up to then? Supplemental information from acn 161523: it is impossible to visually check the wheel well area of the engines from the cockpit. It would also be wrong to lower the landing gear so as to view the wheel well area, as the flow of any air into this area would increase and spread any fire there. We treated it as an engine fire and completed the engine fire phase I and phase ii checklists. This procedure ensures that adequate fire extinguishing agent is discharged into the engine and wheel well compartments. The rdd fire crew told us there was not sign of fire, smoke or excess heat around the right engine. I believe we handled this incident by the book. I gratefully commended the company training department for bringing to our attention and giving us the knowledge of how to handle this type of situation in which no specific written procedure exists. It is our responsibility as flight crew members to ensure the safety of our passenger, crew and aircraft.

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Original NASA ASRS Text

Title: COMMUTER LTT DECLARED AN EMERGENCY AND DIVERTED TO ALTERNATE WHEN THE RIGHT ENGINE WHEEL WELL FIRE LOOP INOPERATIVE LIGHT ILLUMINATED.

Narrative: UPON LEVELING OUT AT 15000', WE HAD THE ENG FIRE/WHEEL WELL DETECTOR INOP LIGHT ILLUMINATE. OUR CHKLIST AND PROCS FOR THIS, WHEN IT HAPPENS IN CONJUNCTION WITH AN ENG FAILURE, IS TO TREAT IT AS AN ENG FIRE; I.E., ENG SHUTDOWN AND EXTERIOR AGENT. THERE IS NO SPECIFIC PROC WHEN IT COMES ON W/O AN ENG FAILURE, SO I OPTED TO USE THE SAME PROC (SHUTDOWN, DECLARE EMER, DISCHARGE BOTTLE) FOR SAFETY'S SAKE. (ONCE THE DETECTOR IS INOP, ONE DOESN'T KNOW IF ONE HAS A FIRE OR NOT.) A CATASTROPHIC FIRE COULD INSTANTLY DISABLE THIS KIND OF SENSOR CIRCUIT. THE QUESTION HAS ARISEN FROM MGMNT WHETHER THIS WAS A PRUDENT COURSE OF ACTION, CONSIDERING NO VISIBLE EVIDENCE OF FIRE WAS NOTED. IF WE ARE TO TREAT THIS SITUATION AS FIRE WITH ENG FAILURE, WHY SHOULD IT BE DIFFERENT W/O AN ENG FAILURE? DON'T MOST ENG FIRES OCCUR W/O AN ASSOCIATED FAILURE? WITH THIS PARTICULAR TYPE OF ENG COWLING AND LOCATION, YOU CANNOT BE SURE OF NO FIRE JUST BE LOOKING OUT THE WINDOW. SO THE QUESTION I HAD TO ASK MYSELF AT THE TIME WAS, DO I JUST ASSUME THERE IS NO PROB AND HOPE EVERYTHING IS OK AND DO NOTHING, OR PLAY IT SAFE AND TREAT IT AS AN EMER? KEEP IN MIND, IT IS DRILLED INTO US DURING TRNING THAT A DETECTOR INOP WARNING IS TO BE TREATED AS A FIRE (WITH AN ENG FAILURE). AGAIN, WHY SHOULD THERE BE A DIFFERENCE W/O AN ENG FAILURE? AND IF THERE IS TO BE A DIFFERENCE, IT IS NOT SPELLED OUT IN PROCS. I FELT I HAD ACTED IN THE SAFEST MANNER, CONSIDERING IT WAS CAVU AND THE ARPT WAS IN SIGHT. WE LANDED W/O INCIDENT. ANOTHER THOUGHT PROCESS WAS, IF I DIDN'T DO ANYTHING AND THERE WAS A SITUATION THAT WORSENED, WHO WOULD I ANSWER UP TO THEN? SUPPLEMENTAL INFO FROM ACN 161523: IT IS IMPOSSIBLE TO VISUALLY CHK THE WHEEL WELL AREA OF THE ENGS FROM THE COCKPIT. IT WOULD ALSO BE WRONG TO LOWER THE LNDG GEAR SO AS TO VIEW THE WHEEL WELL AREA, AS THE FLOW OF ANY AIR INTO THIS AREA WOULD INCREASE AND SPREAD ANY FIRE THERE. WE TREATED IT AS AN ENG FIRE AND COMPLETED THE ENG FIRE PHASE I AND PHASE II CHKLISTS. THIS PROC ENSURES THAT ADEQUATE FIRE EXTINGUISHING AGENT IS DISCHARGED INTO THE ENG AND WHEEL WELL COMPARTMENTS. THE RDD FIRE CREW TOLD US THERE WAS NOT SIGN OF FIRE, SMOKE OR EXCESS HEAT AROUND THE RIGHT ENG. I BELIEVE WE HANDLED THIS INCIDENT BY THE BOOK. I GRATEFULLY COMMENDED THE COMPANY TRNING DEPT FOR BRINGING TO OUR ATTN AND GIVING US THE KNOWLEDGE OF HOW TO HANDLE THIS TYPE OF SITUATION IN WHICH NO SPECIFIC WRITTEN PROC EXISTS. IT IS OUR RESPONSIBILITY AS FLT CREW MEMBERS TO ENSURE THE SAFETY OF OUR PAX, CREW AND ACFT.

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.