As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA- NR 1 ENGINE BLEED AIR PRODUCES BLUE HAZE WHEN FIRST TURNING ON AFTER ENGINE START. HAZE AND ACCOMPANYING SMELL LAST ONLY 2-4 MINUTES. CLEANED CARBON BUILDUP ON NR 1 P2.5-3 SWITCHING VALVE. NO SMOKE OR SMELL NOTED. NO PARTS REPLACED, OPERATIONAL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.