As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS SIGNIFICANT SYS - LEFT ENGINE N1 INDICATOR (PRIMARY) SHOWING ERRONEOUS FLUCTUATIONS IN CRUISE FROM 94 PERCENT TO 86 PERCENT INTERMITENTLY. SAME ON SECONDARY. OTHER PARAMETERS NORMAL. R & R NR1 ENG N1 SPEED SENSOR IAW MM77-12-01. OPS CHECKS NORMAL. OK FOR SERVICE. GRD RUN NORMAL NR1 ENG N1 IND. OPS CK GOOD. SECURED COWLINGS.