Date: 202111
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: APU Pneumatic System & Ducting
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Flight Attendant (On Duty)
Reporter qualification: Flight Attendant Current
Human factors: Physiological - Other
Second reporter function: Flight Attendant (On Duty)
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Flight Crew
When detected: Aircraft In Service At Gate; Pre-flight
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After leaving our inbound flight; the Flight Attendant (F/A)-4; and I walked to our outbound gate.  Our next aircraft was deplaning.  We were able to get on the aircraft early; around XA:45.  Neither of us noticed any odor when we boarded the aircraft.  We were wearing our face masks.  Eventually the F/A-2; Captain and First Officer arrived.  We had a briefing with the Captain.  After the briefing the Captain and the First Officer wanted coffee. To brew the coffee the APU was started.  The boarding process began on time.  Early in the boarding process; the Captain stopped boarding due to a mechanical issue unrelated to the odor/fume issue.  Approximately 25 passengers were aboard before boarding was stopped.  They remained on board until the decision was made that the aircraft would be staying in ZZZ for maintenance.  During the halt in boarding; the Captain made several trips to the back of the aircraft and also up the jetway and back to the aircraft.  On one of his early (2nd maybe) trips he stopped in the galley to ask F/A-4 and me if we could smell anything.  Unfortunately; I had just opened the oven to heat up crew meals for the Captain and First Officer.  The only thing you could smell in the forward galley was that nasty odor that lives in all aircraft ovens.  It wasn't until all of us got off the aircraft that I could smell an odor.  I had taken my mask off and was standing near the bottom of the jetway when I noticed the odor.  When I went closer to the aircraft the odor was more noticeable.  To me the odor smelled like an old dirty wet carpet or damp old upholstered furniture. (Not the nasty oven smell.)  Symptom wise; I had a very slight headache; my eyes were extremely bloodshot; I had brain fog and was extremely tired on [date] afternoon and evening.  [Day after] I spent most of the day sleeping/napping and went to bed early (XK:30).


Second narrative: I was flying position 4; so I was forward near 1L door with FA1 (Flight Attendant) for boarding. The Captain was in the flight deck and called out asking FA1 if coffee was made.  FA1 stated the APU needed on to make coffee.  The Captain started the APU.  Boarding began and only a few passengers were on board when the Captain advised us that he stopped boarding for a maintenance issue. The Captain walked through main cabin to aft galley where he spoke with FA2. The Captain returned to the fwd galley and asked us; FA1 and FA4 if we could smell anything unusual. Just before the Captain had asked us this question; FA1 had opened the oven door to put pilot meals inside. FA1 and FA4 both told the Captain that all we could smell was the stinking oven. The Captain informed us that he smelled an odor other than the ovens and told us he was having maintenance look into it. We were eventually notified that we would be deplaning and moving to new gate/new aircraft. We deplaned and left the aircraft. The Captain; First Officer; and all 3 flight attendants stepped onto the jetway. At this time; FA1 removed her mask and said she could now smell something. I; FA4; removed my mask and agreed that there was some sort of an odor. FA2 then stated he could smell something while in main cabin/aft galley. Crew proceeded to new gate/new aircraft and finished duty day in ZZZ1.


Synopsis: A319 flight attendant crew reported a fumes event during passenger boarding. Shortly thereafter; the Captain informed the crew to stop boarding and that maintenance would assign an aircraft swap.