What was found
COCKPIT ODOR: JUST AFTER LEVEL OFF AT FL 380 A FAINT BUT DISTINCT ODOR WAS NOTICED. IT WAS INTERMITTENT WHILE IN CRUISE BUT BECAME STRONGER DURING THE DESCENT. NO SIGN OF SMOKE AND ALL AIRCRAFT SYSTEMS WERE NORMAL. // SIGNOFF// PERFORMED ENGINE RUNS TO OPERATE ECM. CYCLED COCKPIT AND CABIN TRIM AIR VALVES MULTIPLE TIMES. COMPLETED NETJETS TASK CARD IAW TC-68A-21-181006MR2 REVISION DATE 02-16-2022. REMOVED HEPA FILTER P/N 9914836-1 S/N 0895 AND INSTALLED NEW HEPA FILTER P/N 9914836-1, S/N 0847 IAW CE-680A-21-70-10. NO DEFECTS FOUND