What was found
CREW REPORTED A STRONG CABIN ODOR WHILE ON TAXI-OUT & THROUGH CLOUDS ON CLIMB OUT. ODOR DISSIPATED AT CRUISE & RETURNED ON DESCENT, WORSE IN THE CLOUDS & CLEANED UP BEFORE LANDING. R & R APU STARTER O RING IAW MM 49-42-51 & WASHED APU. OPERATIONS GOOD NO LEAKS FOUND. COMPLIED WITH JOB CARDS 26L00021001, 26L00021002 & 26L00021004, DECONTAMINATION OF ECS. NO ODOR AT THIS TIME. ACFT OK FOR RETURN TO SERVICE.