What happened
On 22 July 2013, a Cessna 525B, registered F-HCIC, was performing a commercial positioning flight from Paris Le Bourget to Lannion when the crew encountered a sudden influx of thick black smoke in the cockpit. While climbing through FL 180, the crew detected a strong burning smell, followed rapidly by dense smoke entering from the rear of the cabin.
In the ensuing chaos, the captain lost his headset and glasses while attempting to don oxygen masks. The captain initiated an emergency descent, which included a significant nose-down pitch. During the descent, the aircraft experienced overspeed warnings and approached a TCAS Traffic Advisory situation. The crew's communication was severely hampered by the captain's lack of a headset and the high stress of the situation. Despite the difficulty in maintaining the flight path and navigating through the Paris airspace, the crew managed to land the aircraft at Paris Le Bourget without visible external damage.
The investigation
The BEA investigation focused on the mechanical failure of the left engine and the crew's response to the smoke. Examination of the Williams International FJ44-3A engine revealed that the No. 2 intermediate bearing had failed. This failure caused the high-pressure shaft to move, damaging seals and allowing oil to leak onto hot engine components, which subsequently produced the smoke that entered the cabin via the air conditioning system.
The investigators also examined the crew's performance, noting that the captain's priority was a rapid descent, which led to deviations from standard operating procedures, such as not using the Quick Reference Handbook (QRH) and not announcing the engine shutdown to the copilot. The investigation also looked into the training adequacy for high-performance aircraft (HPA) and the effectiveness of air traffic control coordination during the emergency.
Findings
- The primary cause of the smoke was the failure of the No. 2 intermediate bearing in the left engine.
- The failure of the bearing seals allowed engine oil to leak and burn, contaminating the cabin air via the air conditioning system.
- The crew's ability to manage the emergency was compromised by the suddenness of the smoke, the loss of the captain's communication headset, and the lack of protective goggles.
- There was a lack of effective teamwork and communication between the pilot flying and the pilot monitoring due to the high workload and the captain's inability to hear the copilot or ATC.
- The aircraft's flight path became unstable, leading to an overspeed condition and a temporary loss of separation from other traffic.