As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED LT ENGINE BEGAN TO SURGE IN POWER IMMEDIATELY AFTER TAKEOFF, DROPPING AND SPIKING UP TO 5 PERCENT N1. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE PERFORMED GROUND ENGINE RUN AND FOUND LT ENGINE N1 SURGING ABOVE 80 PERCENT N1 WITH SPEED SWITCHES ON, BUT STABLE WITH SPEED SWITCHES OFF.