Date: 201911
Location: ZZZ.Airport, US
Aircraft: A321
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: APU
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate; Pre-flight
Result: General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: First Officer (FO) entered flight deck for preflight. FO immediately noticed musty odor on flight deck. Odor was not noticeable throughout rest of aircraft. FO went to do walk around to check exterior for possible causes; and suspected odor may be gone upon return. The maintenance log was not on board. The FO also noticed work being done in the forward avionics bay from terminal window prior to boarding the aircraft. This occurred after an equipment change on the sequence. Upon returning from the walk around; the odor was still present and very strong; but only on the flight deck. FO asked flight attendants if they noticed any odors in the cabin; they agreed there were none. One flight attendant accompanied FO back to flight deck to check for the odor. The flight attendant agreed that there was a strong old sock smell only on the flight deck. The FO tried to gather more information about the aircraft by calling Operations (Ops) and Maintenance to inquire as to the reason for the equipment change and the reason the Maintenance log was not on board the aircraft. Ops did not have any information on the equipment change; and Maintenance said they were working off some write-ups on the log but did not explain what they were. The Captain was not yet on board; the FO made a decision to report the odor to Maintenance; hold off boarding and inform the flight attendants as to the issue. When the FO reported the odor to Maintenance via the Maintenance frequency; the respondent asked the FO if the APU bleed was on. The FO responded that it was on. The respondent request the FO turn off the APU bleed. The FO immediately turned off the APU bleed. As soon as the APU bleed was turned off; the odor began to dissipate until it was barely noticeable within about 3 minutes. After the bleed was turned off; the FO went to the top of the gate to inform the agent to hold off boarding. The Captain was there printing paperwork. After being joined by the Captain and Maintenance representatives; the FO promptly completed an Odor report and sent it; as well as filled out a discrepancy in the Maintenance log. The station Chief Pilot called the FO and informed him the form was never received. The FO resubmitted the Odor form and it seemed to have went that time. The FO also; at the request of the Chief Pilot; emailed screen shots of the report to the Chief Pilot and submitted report. The FO did not follow the QRH for fumes due to being at the gate and having access to Maintenance. If I had it to do again; I would have also pulled out the QRH.




Synopsis: A321 First Officer reported musty odor in the flight deck during preflight; which was diagnosed; albeit without reference to the QRH.