What happened
On March 25, 2024, an Airbus A340-313, registration HB-JMD, was performing a scheduled commercial flight from Bogotá (SKBO) to Cartagena (SKCG) before continuing to Zurich (LSZH). During the initial climb phase from the Cartagena leg, while passing through approximately 5,300 feet, the flight crew noticed an electrical odor. Shortly thereafter, cabin crew reported the presence of smoke and significant heat within the passenger cabin.
Simultaneous with the smoke, the flight deck received warnings regarding a fault in the Air Pack 2 regulator and the Pack 2 Air Cycle Machine. Due to the developing situation, the crew donned oxygen masks and some cabin crew utilized protective breathing equipment. The crew decided to divert to Ernesto Cortissoz International Airport (SKBQ) in Barranquilla, as it offered more favorable runway conditions for an emergency arrival. The aircraft landed at 04:03 UTC, and upon stopping, the crew noted extremely high brake temperatures, with readings reaching between 570°C and 700°C. The aircraft was subsequently taxied to the apron for passenger disembarkation.
The investigation
The investigation, led by the Colombian authorities (DIACC) in coordination with the Swiss Transportation Safety Investigation Board (STSB), focused on the failure of the aircraft's environmental control system. Technical inspections of the Air Cycle Machine (ACM) were conducted at a facility in Frankfurt, Germany.
Investigators examined the internal components of the Honeywell-branded ACM. The inspection revealed that while there was no structural damage to the turbine components, the unit showed evidence of improper internal alignment and axial friction marks on the casing, suggesting that the blades had made contact with the internal surfaces. The investigation focused on the degradation of the unit's bearings given its high total flight hours.
Findings
- The primary cause of the smoke and heat in the cabin was a failure within the Air Cycle Machine (ACM) No. 2.
- The investigation identified a likely catastrophic failure of the air bearings (both journal and thrust bearings) or a compressor wheel burst, leading to a rotational imbalance.
- The high total time since new (over 70,000 flight hours) was noted as a factor in the expected deterioration of the pneumatic bearings.
- There were no injuries to the 314 passengers or 13 crew members on board.