Narrative:

Just after liftoff from yak, the fire bell sounded and all 3 fire lights (engines 1 & 2 and APU) illuminated. Ceilings were variable 600' to 1500' with visibility 2 1/2 mi in fog and rain and a 10-15 KT wind out of the northeast. We immediately turned downwind, remaining in VMC, and landed uneventfully. The problem proved to be rainwater entering various control electronics boxes in the east&east bay. The water most likely entered through the forward entries and main cargo door area during turnarounds at stations where it was raining. The water seeps into the smoke vent/grille in the forward galley area and then down to the electronics bay. Water accumulates in a drain pan especially designed for isolating water intruding into the east&east bay but the drains were plugged with dirt and debris, allowing the drain pan to fill (and overflow at aircraft rotation). We submitted a recommendation to our company to inspect the drain pans more frequently, particularly since precipitation is the norm at the airports we serve during the winter season. Supplemental information from acn 97124: we noted that the #2 engine overheat light was also on. We retarded the throttle to flight idle per the flight handbook but did not shut down the engine since I suspected this was an electrical malfunction rather than an actual overheat or fire. Due to high workload I did not brief the passenger or F/a's.

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Original NASA ASRS Text

Title: ACR MLG RETURN LAND WHEN BOTH ENGINE AND APU FIRE WARNINGS ACTIVATED DURING ICB.

Narrative: JUST AFTER LIFTOFF FROM YAK, THE FIRE BELL SOUNDED AND ALL 3 FIRE LIGHTS (ENGS 1 & 2 AND APU) ILLUMINATED. CEILINGS WERE VARIABLE 600' TO 1500' WITH VIS 2 1/2 MI IN FOG AND RAIN AND A 10-15 KT WIND OUT OF THE NE. WE IMMEDIATELY TURNED DOWNWIND, REMAINING IN VMC, AND LANDED UNEVENTFULLY. THE PROB PROVED TO BE RAINWATER ENTERING VARIOUS CONTROL ELECTRONICS BOXES IN THE E&E BAY. THE WATER MOST LIKELY ENTERED THROUGH THE FORWARD ENTRIES AND MAIN CARGO DOOR AREA DURING TURNAROUNDS AT STATIONS WHERE IT WAS RAINING. THE WATER SEEPS INTO THE SMOKE VENT/GRILLE IN THE FORWARD GALLEY AREA AND THEN DOWN TO THE ELECTRONICS BAY. WATER ACCUMULATES IN A DRAIN PAN ESPECIALLY DESIGNED FOR ISOLATING WATER INTRUDING INTO THE E&E BAY BUT THE DRAINS WERE PLUGGED WITH DIRT AND DEBRIS, ALLOWING THE DRAIN PAN TO FILL (AND OVERFLOW AT ACFT ROTATION). WE SUBMITTED A RECOMMENDATION TO OUR COMPANY TO INSPECT THE DRAIN PANS MORE FREQUENTLY, PARTICULARLY SINCE PRECIPITATION IS THE NORM AT THE ARPTS WE SERVE DURING THE WINTER SEASON. SUPPLEMENTAL INFO FROM ACN 97124: WE NOTED THAT THE #2 ENG OVERHEAT LIGHT WAS ALSO ON. WE RETARDED THE THROTTLE TO FLT IDLE PER THE FLT HANDBOOK BUT DID NOT SHUT DOWN THE ENG SINCE I SUSPECTED THIS WAS AN ELECTRICAL MALFUNCTION RATHER THAN AN ACTUAL OVERHEAT OR FIRE. DUE TO HIGH WORKLOAD I DID NOT BRIEF THE PAX OR F/A'S.

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.