What was found
WHEN BLEEDS TURNED ON AFTER TAKEOFF, ODOR LIKE DIRTY GYM SOCKS COMES OUT AND LASTS FOR 6 TO 10 MINUTES. THEN CLEARS UP. UPON INSPECTION, FOUND WATER DRAIN FILTER COMING OUT OF CONDENSER/MIXER PLUGGED. CLEANED FILTER AND REINSTALLED DRAIN LINE IAW DHC-8 -200 AMM 21-50-21, PAGE 404, STEP 3.A(7). PERFORMED FUNCTIONAL TEST OF BLEED AIR SYSTEM. ALL CHECKS GOOD. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.