B737-800
Flight Crew Air Transport Pilot (ATP)
Physiological - Other; Time Pressure; Training / Qualification
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Took Evasive Action; Flight Crew Became Reoriented; Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft; Procedure; Human Factors
After takeoff the Captain and I noticed a strong (oily) dirty sock odor. We got a call from the aft galley Flight Attendant station at around 1;500 FT indicating them smelling the (oily) dirty sock smell also. The smell was not decreasing so we donned our O2 masks and established Communications. We asked for a level off at 3;000 FT from ATC and notified them of an odor in the aircraft. We declared an emergency. ATC was very accommodating and gave us a choice of runways. We turned OFF the packs and engine bleeds to eliminate the fumes. When the Captain called back to the flight attendants after making a PA the flight attendants said the smell had dissipated. We returned to Runway 36. Airfield Rescue and Fire Fighters followed us to the gate and confirmed the aircraft was not smoking and did not have detectable fumes. After we arrived at the gate and the mechanics were onboard they informed us an engine wash was performed when it was overnight. As of this report I am not sure if that was the cause of the smell or it is an actual oil seal in the compressor section. A test is scheduled to be performed later in the day to confirm the cause. In order to possibly prevent this in the future; knowledge of the engine wash would have been helpful in our decision making.
I suspect that the odors experienced throughout the aircraft to be residue from the chemicals used in this procedure entering the cabin via the bleed air system. I have no way of knowing if the engine wash procedure was completed properly; if it was; the procedure needs to be reviewed and changed to prevent any further occurrences like we experienced.
A B737-800 returned to land after takeoff because a strong dirty socks odor was detected in throughout the aircraft. Maintenance stated an engine wash was completed the previous night so the odor may be a chemical residue.