What was found
DURING CLIMB NR 2 ENG N1, FF, EGT BECAME UNSTABLE, ASSOCIATED WITH ENGINE SURGING. FADEC GRD TEST, FOUND FAULT CODE 352-21 ON CH A. N1 SPEED SENSOR PERFORMED TSM PROCEDURE 73-21-30 352-21 FIG 102 SHEET 28. CHECKED BOTH CH A AND B SYS GOOD. SPEED SENSOR IS 116 OHMS AT THE HARNESS. THE ECU CHECKED BAD PER STEP 12. REMOVED AND REPLACED ECU IAW AMM 73-21-01-4 05. ENGINE RUN AT HIGH POWER IAW JRH. ALL INDICATIONS STABLE. NO FAULT CODES AFTER RUN. ITEM CLEARED