What was found
AIRCRAFT GROUNDED. ODOR EVENT DURING DESCENT. DURING FLT TO DTW USED ELIMINATION OF ODOR CHECKLIST DURING DESCENT WITH FLT CREW USING O2 MASK. AFTER DETECTING ODOR, AFTER PACK 1 WAS OFF FOR 5-10 MINS, DURING APPROACH & LANDING, ODOR DISSIPATED. DURING TAXI, PACK 1 ON & STRONG ODOR OF DIRTY SOCKS, IN COCKPIT & CABIN. PACK 1 OFF & ODOR DISSIPATED, DURING POST FLT, 1ST OFF NOTICED STRONG ACRID ODOR, PLASTIC ODOR FROM INTERIOR OF FRONT OF ENG 1, NO ODOR FROM NR 2. BOTH ENGS, NORMAL INDS, ALL PHASES OF FLT & TAXI. ACFT RFS. PACK 1 REQUIRES DEFERRAL. PLACED ON MEL 21-52-01B, PLACARDS INSTALLED. ACFT OK FOR SERVICE. R & R PACK 1, TESTED, NO DISCREPANCIES NOTED IAW AMM 21-52-41-000-001-A & 21-52-41-400-001-A.