What was found
SUPPLEMENTAL TO HALA2023040300076. UPDATED WITH RESOLUTION. ETOPS - APU FREQUENCY 387HZ AND AMBER. EITHER PACK-1 OR PACK-2 ON WILL CAUSE APU FREQUENCY TO FLUCTUATE FROM (384HZ-387HZ, 96%RPM), WHEN BOTH PACKS ARE OFF ALL STABILIZES (115V/400HZ-100%RPM) AND STEADY. REMOVED AND REPLACED GAPCU PER AMM 24-41-34. CONDITION SAME, RE-INSTALLED OLD GAPCU. REMOVED AND REPLACED FCU PER AMM 49-32-51. LEAK CHK GOOD, CONDITION SAME. SLAVED ECB INSTALLED, CONDITION SAME. RE-INSTALLED ORIGINAL ECB. WITH PACKS OFF APU GEN AT CONSTANT 400 HZ. RAN SINGLE PACK AND BOTH PACKS FOR 2 HOURS AND FREQUENCY FLUCTAUTED BETWEEN 395 TO 398 HZ. THESE VALUES WITHIN LIMITS PER A330 AMM 24-23-00. UNABLE TO DUPLICATE FAULT. ALL CHECKS OK. MEL CLEARED. PLACARD REMOVED