What was found
AFTER DEPARTURE, PILOT NOTICED WHAT APPEARED TO BE SMOKE ENTERING THE COCKPIT AREA. TURNED OFF BLEED AIR & DIVERTED BACK, LANDED WITHOUT FURTHER INCIDENT. MX PERFORMED ENGINE RUNS WITH BLEEDS ON TO CLEAR BLEED LINES FROM WATER & SOAP SOLUTION USED DURING POWER RECOVERY, ENGINE WASHED A DAY BEFORE. NO SMOKE DETECTED AFTER ENGINE RUN UP.