Overview

• Delta confirms it began the APU swap in 2022 and says the program on its Airbus A320 fleet is now more than 90% complete.
• Investigations report a recent rise in fume events, especially on A320-family jets, with Airbus previously citing APU integration as a contributor.
• APU oil leaks can contaminate bleed air feeding the cabin and cockpit, and clinicians have documented nervous-system injuries and flight disruptions linked to such exposures.
• Delta is testing alternative synthetic turbine oils, while United says it proactively tracks oil consumption and replaces APU seals, and the Boeing 787 uses a different architecture that avoids the issue.
• Manufacturers and airlines say events are rare and aircraft meet regulations, as Airbus pursues future design changes such as relocating the APU air inlet and suppliers roll out seal updates.