What was found
FLIGHT 9196, TLV - PHL - DURING DESCENT ON FERRY FLIGHT THE ODOR RETURNED THROUGH THE CABIN FROM PREVIOUS FLIGHT. THE ODOR IS DESCRIBED AS "ACRID - BURNT OIL" SMELL. THE ODOR WOULD DISSIPATE WHEN THRUST WAS NOT AT IDLE. MAINTENANCE INSPECTED AND CLEANED APU BLEED AIR DUCT. REMOVED, CLEANED AND INSPECTED BOTH HP BLEED VALVES FOR CONTAMINATION. ACCOMPLISHED BORESCOPE BOTH ENGINES HP COMPRESS BLADES STAGES 3 THRU 6. REPLACED CABIN RECIRC FILTERS. ACCOMPLISHED HIGH POWER ENGINE RUN.