Incident Overview
On 15 September 2015, an Avro 146-RJ100 (registration HB-IYQ) operated by Swiss Global Air Lines AG arrived at Zurich Airport (LSZH) on a scheduled flight from Munich. After passengers deplaned, several complained of eye and throat irritation, and some were coughing. The commander entered the cabin and soon experienced the same symptoms. He declared the aircraft unserviceable and notified maintenance.
Sequence of Events
Prior to the incident, on the preceding flight from Zurich to Munich, the crew observed that the hydraulic fluid level in the yellow system was at medium. No fluid was added before the return flight. After parking at Zurich, the reservoir level had dropped to one third.
Investigation Findings
Maintenance personnel who entered the cabin quickly detected an odor and determined that the air contamination was caused by leaking hydraulic fluid. The contamination spread because the hydraulic fluid reservoirs are located in a pressurized compartment whose air mixes with cabin air.
The leak was traced to a pipe connection at a valve of the anti-skid system, which is used during braking. Both the valve and the connection were replaced. After refilling the hydraulic fluid reservoir, the aircraft was returned to service.
The aircraft was not damaged. No injuries were reported among the 4 crew and 67 passengers.