Delta replaces APUs on Airbus jets after reports of toxic fume incidents

A recent Wall Street Journal investigation reported an increase in so-called "fume events," with many linked to Airbus’s A320 family. Passengers and crew have described these odors as metallic. The fumes are considered toxic and may cause brain injury or permanent damage to the nervous system.

"The fumes are toxic and can cause brain injury and permanent damage to the peripheral nervous system," Robert Kaniecki, a neurologist and consultant to the Pittsburgh Steelers, told the publication. He said he has treated around a dozen pilots and over 100 flight attendants for brain injuries related to fume exposure over two decades. One patient was a frequent Delta flyer who suffered an injury in 2023.

Delta currently operates 518 Airbus jets, with 321 belonging to the A320 family: 127 Airbus A321-200s, 83 Airbus A321neos, 57 Airbus A319s, and 54 Airbus A320-200s. The average ages range from under two years for some models up to nearly thirty years for others. The airline awaits delivery of another 72 new A321neo aircraft but has not specified if they will have updated APUs installed. According to CBS News, Delta has already replaced APUs on about ninety percent of its existing fleet in this category.

Other airlines are also working on solutions. United Airlines CEO Scott Kirby told CBS News that he has focused on this issue for more than ten years: "United operates a ‘proactive maintenance program’ that monitors engine oil consumption and pressure, and replaces APU seals in advance to prevent oil leaks and burns that could release fumes into the cabin."

Pilot and flight attendant associations globally continue calling for action so that cabin air remains free from hazardous gases or vapors. Some incidents have been severe enough that crews needed oxygen masks during flights.

Industry reports suggest alternatives such as bleed-free pressurization systems or filtration could help reduce risks associated with bleed air contamination. The Boeing 787 uses such technology by not relying on bleed air; similar approaches have been tested successfully as retrofits on other aircraft types like the ATR72.