What was found
DET FIRE APU' EICAS ADVISORY MESSAGE DISPLAYED. APU FIRE LOOP A AND B FAILURE. CKD APU COMPART AREA, NO EVIDENCE OF FIRE. PERFORMED GROUND TEST, FOUND APU FIRE LOOP B FAIL , MSG 26037. LOOP A OPERATION NORMAL ALSO SQUIB TEST NORMAL. REF FIM 26-15-00-812-TASK 807, NOTE (A21) CARD HAD BEEN PREVIOUSLY REPLACED ON 11JUN10. PERFORMED CHECKED RESISTANCE BETWEEN PIN 19 AND PIN 20 AS REQUIRED PER FIM, RESISTANCE READ 24.95 K OHMS AND MEASURED PIN 19 AND 230640PIN20 TO GROUND, FOUND OPEN CIRCUIT. SUSPECT DETECTOR AT FAULT. APU FIRE TEST, PASSED. NO MSG FOUND. REPLACED FIRE LOOP DETECTOR. OPERATIONS NORMAL.