What happened
On 24 April 2024, an Airbus A320-214, registration EI-DEJ, was performing a positioning flight from Madrid-Barajas Airport to Dublin Airport. The aircraft was being ferried without passengers or cabin crew for landing gear maintenance. Shortly after departure from Spain, the pilot detected a faint chemical smell, which the crew noted had dissipated in the cockpit but remained present in the rear galley.
As the aircraft descended through approximately 6,500 feet toward Dublin, the situation escalated significantly. Both pilots encountered a very strong chemical odor within the flight deck. Due to the intensity of the fumes, the pilot ordered the immediate use of flight crew oxygen masks. The crew continued the approach to Runway 2D8L without requesting assistance from air traffic control, as the aircraft was already established on the localizer. The masks were removed at roughly 600 feet to maintain visibility and communication, though the odor remained noticeable until the aircraft landed and taxied to its stand.
Following the landing, the crew sought medical evaluation at a local hospital. While clinical tests, including blood work and ECGs, showed no immediate abnormalities, the pilot reported experiencing fatigue and tingling in the left arm for several weeks, and the first officer experienced a headache and throat pain.
The investigation
The AAIU examined the aircraft's pneumatic and air conditioning systems, as well as the history of the Auxiliary Power Unit (APU). The investigation revealed that the aircraft had a history of similar odor reports dating back to February 2024. Maintenance efforts, including decontamination procedures, had previously failed to resolve the issue.
Technical analysis of the APU showed that oil had been present on the inlet plenum screen. Subsequent inspections of the APU units involved in the incident confirmed that external oil leaks had occurred. Specifically, workshop reports for the APU units indicated that oil from an external leak had been drawn into the system.
Findings
- The primary cause of the fumes was the contamination of the air conditioning system caused by the ingestion of oil from an external APU leak into the load compressor.
- Previous maintenance attempts to identify and rectify the source of the odors had been unsuccessful.
- The aircraft's airworthiness and the crew's licenses were all valid at the time of the event.
- The crew's symptoms, while not linked to specific clinical abnormalities, persisted for varying periods following the exposure.