What happened
On 10 February 2023, a Boeing 767-332(ER), registration N197DN, was performing a scheduled passenger service from Edinburgh to New York JFK. Shortly after takeoff, a high-pressure turbine blade in the right engine fractured. This failure triggered a chain reaction, damaging five additional blades and creating a significant engine imbalance. The resulting intense vibrations were felt throughout the cabin, prompting the flight crew to divert the aircraft to Prestwick Airport.
During the descent, the extreme vibrations caused a fatigue fracture in a slat track housing drain tube. This breach allowed fuel to escape from the right wing tank. As the fuel streamed from the wing, it was ignited by the hot engine exhaust, creating visible flames that were captured on passenger video. Despite the flames, the crew remained unaware of the fire during the approach. The aircraft landed at Prestwick with no fatalities and no injuries, but upon reaching the stand, a significant fuel leak was discovered by ground personnel, necessitating rapid passenger disembarkation and emergency containment measures.
The investigation
The AAIB examined the engine and the fractured drain tube components. Metallurgical analysis of the turbine blade revealed that the initial failure originated from stress corrosion cracks, likely exacerbated by sulphation attack (hot corrosion) and pitting. The investigation also focused on the drain tube, which had fractured due to the mechanical stress of the engine's out-of-balance rotation. Investigators found that the fatigue crack in the tube had developed and fully failed within the duration of this single flight. Furthermore, the investigation reviewed the crew's management of the overweight landing and the effectiveness of the airport's emergency response.
Findings
- A high-pressure turbine blade failure in the right engine caused a massive imbalance.
- The engine vibration was the primary cause of the fatigue fracture in the slat track housing drain tube.
- The fractured tube allowed fuel to leak from the right wing tank into the dry bay and out through a drain hole.
- The escaping fuel ignited upon contact with the hot engine exhaust during flight.
- The aircraft landed with a significant amount of fuel remaining, and the leak was eventually stopped by transferring fuel to the centre tank.