What happened
On 18 August 2011, an Airbus A320-233, registration HA-LPB, arrived at Skavsta airport in Södermanland County after a scheduled commercial flight from Budapest. The aircraft landed according to standard procedures and taxied to its parking stand.
Upon shutting down the engines at approximately 21:25, ground personnel observed flames and a glow emanating from the left engine (engine number one), along with smoke visible from the second engine. This prompted the immediate activation of the airport fire brigade and a serious incident alarm. In response to the visible fire, the crew performed engine cranking procedures to ventilate any remaining fuel, which caused the visible flames and smoke to dissipate. Passengers were able to disembark the aircraft normally while emergency services remained on standby.
The investigation
The Swedish Accident Investigation Authority (SHK) conducted a technical examination of the aircraft and its engines. Investigators reviewed the Digital Flight Data Recorder (DFDR) and performed a physical inspection of the engines in accordance with the aircraft maintenance manual.
During interviews, the pilots reported that no cockpit malfunctions or fire warnings were triggered during the engine shutdown process. A technical inspection of the engines revealed no structural damage, discoloration, or evidence of fire. The only notable finding was a small amount of residue in the lower rear outlet of the first engine. To further verify the engine's condition, both engines were restarted and run at idle for five minutes under supervision, during which they operated within normal parameters without any deviations.
Findings
- The investigation could not establish a definitive direct cause for the open flames.
- There were no mechanical failures or malfunctions recorded in the flight data.
- Small amounts of oil or fuel residue likely accumulated in the rear engine outlet and ignited during the shutdown sequence.
- The phenomenon, known as a "tail-pipe fire," is a known occurrence in certain turbofan engines during startup or shutdown and typically does not trigger cockpit fire warnings.
- The presence of residue in the first engine suggests that oil leakage was the most probable cause of the ignition.