Date: 202108
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Other All
Aircraft component: APU Pneumatic System & Ducting
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Physiological - Other
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew; Person Passenger; Person Flight Attendant
When detected: In-flight; Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: When we arrived in ZZZ to start our trip we meet with the inbound crew to discuss the inbound leg and aircraft.  There was no mention from them about any odors or problems with the aircraft.  When we boarded the aircraft we were over come by a strong smell throughout the plane. Looking back it was strange the previous crew didn't mention this. It was similar to a strong carpet cleaner smell or an odor like when you clean an oven.  There was no indication of fire or smoke much less any indications of a malfunction.  We discussed the issue with the crew and found no reasons not to continue safely.  As we boarded the aircraft several passengers started to complain especially in the rear cabin about the odor.  We discussed what the cause of the smell could be and determined that it was not a safety of flight issue since we could not isolate any problems. All systems operated normally.  We agreed to continue on the short flight to ZZZ1 hoping that at altitude the fresh air would dispute any smell.  We felt that since there was smoke all around the area from west coast wild fires that could possibly be the cause.  At cruise the smell seemed to disappear in the cockpit but as we got closer to our destination the FA'S informed us that it remained in the cabin.  There was no smoke or any indications of a malfunction. They then stated that many passengers complained that they were starting to get headaches and feel bad.  We asked if there any immediate concerns and were informed there were none.  Inbound we decided to inform maintenance control that there was an odor which seemed to be coming from the gasper vents via an MRM entry so that on arrival they could trouble shoot and see if they could remove it. After landing we started the APU and received a low oil level indication.  Not sure if this contributed to the problem or not as we accepted the aircraft in ZZZ with the APU operating and had no indications of any problems at that time.  Arriving at the gate we noticed that the smell in the cockpit remained but the cabin was stronger.   We had an hour on the ground before our next flight so felt that the problem could be resolved.  After block in we meet with maintenance and he noticed the smell as well.  His feeling is it smelled like burning oil.  We had no indications at any time of an overheat or fire on any system.  I then received a call from Name our Chief Pilot to contact Name 1 in Maintenance Control for some questions. I was asked generic questions about the entire flight to help trouble shoot the problem. As I stated everything went great expect for the strong smell.  They removed the aircraft from service and we continued our trip with another aircraft.  The entire crew handled the situation professionally and with merit.  I applaud how we worked together to assist passengers needs and answer any questions or concerns they may have had.  The flight was concluded safely and professional with our [company] principles.




Synopsis: A320 Captain reported a fumes event of varying intensity from preflight to arrival at destination where maintenance removed the aircraft from service.