What was found
NOTED A STRONG ODOR FROM PRESSURIZATION SYS WHEN ENGS STARTED & VERY LOUD ROARING SOUND DURING TAKEOFF, CLIMB OUT, DESCENT & LANDING. PERFORMED ENG RUNS & PRESSURIZED ACFT TO 4.2 PSI, AT TAKEOFF POWER SMELLED ODOR WITH NO SMOKE FOR APPROX 5 SECONDS. RETURNED ENGS TO IDLE THEN BACK TO TAKEOFF POWER. ODOR DID NOT RETURN. REPEATED 4 TIMES WITH NO ODOR OR ROARING SOUND IAW AMM 21-31-00 & 71-00-01.