What happened
On August 17, 1999, a Crossair BAe Systems AVRO 146-RJ85, registration HB-IXG, was performing a scheduled commercial flight from Zurich Airport. Shortly after departing from runway 28, the cabin crew reported smoke within the passenger compartment. In response to the developing situation, the pilots donned oxygen masks and declared an emergency at approximately 16:33 LT. The flight crew elected to return to Zurich, requesting radar vectors for an approach to runway 14. The aircraft landed safely at 16:39 LT. Following the landing, a rapid disembarkation was conducted; all 18 passengers and 6 crew members remained uninjured.
The investigation
The investigation focused on the source of the smoke and the mechanical condition of the engines. Physical inspections of all four engines revealed an oil leak specifically located in engine number 4 (S/N LF07412). Investigators noted that the engine had a history of repairs for a similar internal oil leak in 1997. Furthermore, the investigation examined a subsequent ferry flight performed the following day, during which the crew reported a brief smoke warning in the forward lavatory while flying to Basel. The investigation also reviewed the aircraft's maintenance history, noting a previous smoke incident in the forward lavatory on August 11, 1999, which had remained unexplained at that time.
Findings
Technical analysis determined that the smoke was caused by an internal leak in the number 2 bearing area of engine number 4. The investigation found that the sealing surfaces of the number 2 bearing exhibited wear and carbon deposits, which compromised the seal's integrity. This failure allowed oil from the lubrication system to escape into the diffuser. Once in the diffuser, the oil mixed with high-pressure bleed air. This contaminated air was then routed through the high-pressure bleed port toward air conditioning pack #2, eventually entering the aircraft cabin. The brief smoke warning noted during the subsequent ferry flight was attributed to residual oil traces remaining within the air conditioning system.
Safety action
No specific safety recommendations were recorded in the source material regarding new regulatory requirements, though the investigation confirmed that the repair of the identified leak resolved the smoke issues in the cabin.