Narrative:

At approximately 3000 ft MSL, the APU fire warning alerts activated. APU fire warning emergency checklist items were completed and warnings ceased. Within approximately 30-45 seconds, alerts activated again. Emergency was declared with palm beach departure with a request for immediate vectors for an ILS runway 9L approach. Cabin crew and passenger were notified of problem and intentions. All checklists were accomplished and an uneventful landing was made back at the west palm beach airport. Aircraft was stopped on a taxiway clear of the runway while aircraft was inspected by fire department with emphasis on APU area and inside APU access doors. No evidence of fire was found and aircraft was taxied to the gate with a fire department escort. Passenger were deplaned at the gate.

Related reports:

Google
 

Original NASA ASRS Text

Title: SHORTLY AFTER TKOF, AN ACR FLC RETURNED TO LAND AFTER DECLARING AN EMER. AN APU FIRE WARNING HAD BEEN INDICATED, AND AFTER CHKLIST ITEMS WERE COMPLETED, A SECONDARY WARNING ACTIVATED.

Narrative: AT APPROX 3000 FT MSL, THE APU FIRE WARNING ALERTS ACTIVATED. APU FIRE WARNING EMER CHKLIST ITEMS WERE COMPLETED AND WARNINGS CEASED. WITHIN APPROX 30-45 SECONDS, ALERTS ACTIVATED AGAIN. EMER WAS DECLARED WITH PALM BEACH DEP WITH A REQUEST FOR IMMEDIATE VECTORS FOR AN ILS RWY 9L APCH. CABIN CREW AND PAX WERE NOTIFIED OF PROB AND INTENTIONS. ALL CHKLISTS WERE ACCOMPLISHED AND AN UNEVENTFUL LNDG WAS MADE BACK AT THE WEST PALM BEACH ARPT. ACFT WAS STOPPED ON A TXWY CLR OF THE RWY WHILE ACFT WAS INSPECTED BY FIRE DEPT WITH EMPHASIS ON APU AREA AND INSIDE APU ACCESS DOORS. NO EVIDENCE OF FIRE WAS FOUND AND ACFT WAS TAXIED TO THE GATE WITH A FIRE DEPT ESCORT. PAX WERE DEPLANED AT THE GATE.

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.