A319
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
We brought the aircraft in from ZZZ1 arriving at gate in ZZZ at XA:34 local. The flight from ZZZ1 was uneventful. Arriving at gate ramp personnel hooked up ground electric as well as ground air. The APU was shut down after both were connected. Approximately 15 minutes to departure I turned the APU back on. Once on line and available I deselected ground electric. Once the ground crew disconnected both ground electric and air I selected the APU bleed on. Within 30 secs of the APU bleed being selected on I noticed the odor of dirty socks indicating the presence of neurotoxic tricresyl phosphates emanating from the ventilation system. I quickly turned off the APU bleed and asked the First Officer if he noticed the smell as well; however he was unsure. I then proceeded to turn the bleed on one more time to confirm we smelled it and immediately after turning the APU bleed on the odor was back. Again I then selected the APU bleed off. We then asked operations for ground air and electric to be placed back on the aircraft while we called Maintenance Control. We also had the passengers deplane. Maintenance Control had contract maintenance come out and after conferring with Maintenance Control; Airbus Fleet Management; and [name] in the Chief Pilots Office we performed an engine run-up with contract maintenance onboard. We used a ground air cart to perform ground air start; bypassing the APU. Once the pack systems were turned on using the engine bleeds the odor was back; however at a much lighter presence. The bleeds and packs were quickly selected off and we began to shutdown and secure the aircraft. The airplane was taken out of service. Company Maintenance came in from ZZZ2 overnight and confirmed a significant oil leak from the APU. [The cause was an] APU oil leak.
A319 First Officer reported a fume event during preflight at the gate due to an APU oil leak.