What happened
On September 15, 2015, an Avro 146-RJ100, registration HB-IYQ, operating a scheduled flight from Munich to Zurich, experienced an incident involving contaminated cabin air. Upon arrival at Zurich Airport, several passengers reported eye and throat irritation and coughing. The captain experienced similar symptoms after entering the cabin. Due to the presence of an unusual odor and physical symptoms, the aircraft was declared unserviceable, and maintenance personnel were summoned to investigate.
The investigation
Maintenance staff inspected the cabin and identified that the air contamination was caused by leaking hydraulic fluid. The investigation established that the contamination spread into the passenger cabin because the hydraulic fluid reservoirs are located in a pressurized compartment. Air from this compartment mixes with the general cabin air during flight.
Prior to the incident, during the previous flight leg from Zurich to Munich, the crew had noted that the hydraulic fluid level in the yellow system was at a medium level. No fluid was replenished before the return flight to Zurich. By the time the aircraft parked in Zurich, the reservoir level had dropped to one-third of its capacity.
Findings
- The source of the contamination was a leak at a line connection on an anti-skid system valve.
- The leak of hydraulic fluid into the pressurized compartment allowed the substance to enter the cabin air supply.
- The reduction in hydraulic fluid levels from a medium level to one-third capacity indicated an ongoing loss of fluid during the flight.