Incident Summary
On 12 August 2019 at 2100 UTC, an Airbus A320 (registration EI-DEO) operated a commercial passenger flight from Dublin Airport to London Heathrow. The aircraft, manufactured in 2005, was powered by two CFMI CFM56-5B4/PS turbofan engines. There were 173 passengers and 6 crew on board. No injuries or damage occurred.
Sequence of Events
Due to an inoperative APU, the first engine was started on stand using a ground air supply, and the second engine was started after push-back via a cross-bleed procedure. Following the cross-bleed start, both flight crew members detected a strong fuel/oil odor, which they initially attributed to the start process. During taxi, further fuel/oil fumes were noticed, and the crew assumed they originated from the exhaust of an aircraft ahead. Intermittent fumes persisted during departure and climb, and the crew discussed them.
Flight Crew Actions
During the approach briefing, the pilots discussed that they both felt they were not performing to their normal standard. They agreed to maintain heightened awareness but did not consider it necessary to don oxygen masks. The approach and landing were uneventful. After landing, the crew opened the cockpit direct vision windows and taxied to the stand. During a post-flight review, uncertain about their medical condition, both pilots briefly wore oxygen masks. A basic medical examination showed normal vital signs.
Post-Flight and Investigation
Engineering staff conducted extensive fault finding but identified no cause for the fumes. The aircraft returned to operation and has had no further reports of fumes. The operator completed an internal investigation and is reviewing smoke and fumes guidance materials provided to its flight crew.