What was found
(CAN) THE OPERATOR REPORTED A FLAME OUT DURING ROUTINE TAXI FOR TAKEOFF. THE ACFT RETURNED TO HANGAR AND THE MAINTENANCE CREW WAS ABLE TO REPLICATE THE EVENT DURING GROUND RUNS. WHEN REDUCING POWER FROM APPROXIMATELY 70 PERCENT DOWN TO IDLE. A BORESCOPE INSPECTION REVEALED CARBON BUILDUP ON 3 FUEL NOZZLES. TROUBLESHOOTING IS CONTINUING.