What happened
On 12 February 2008, at approximately 00:15, a Job Air SAAB 340B, registration OK-CCD, landed at Lappeenranta aerodrome from Helsinki-Vantaa. During taxiing, the flight crew identified a hydraulic system malfunction and notified air traffic control. To avoid unusual procedures during passenger disembarkation, the crew decided to taxi closer to the terminal building, parking the aircraft slightly away from its usual stand.
As the crew began the engine shutdown procedure by feathering the propellers, the aircraft experienced a sudden surge in thrust, known as a propeller burst or "haukkaus" effect. Because the hydraulic system had depleted, the parking brakes were effectively non-functional. The aircraft lurched forward toward a baggage shelter adjacent to the terminal. The crew attempted to steer the aircraft to the left and closed the fuel cocks to shut down the engines, but the right wingtip struck a corner beam of the shelter roof, causing damage to the wingtip and the structure.
The investigation
The investigation focused on the loss of braking capability and the sequence of the engine shutdown. Investigators examined the aircraft's left main landing gear and discovered a fractured brake line swivel on the inner wheel. Traces of yellow paint on the broken fitting and the landing gear matched paint from a taxiway lighting fixture at Helsinki-Vantaa airport.
It was established that during the aircraft's previous landing at Helsinki-Vantaa, the left main gear had struck a taxiway light. This impact fractured the fitting, leading to a significant hydraulic fluid leak during the taxi at Lappeenranta. The investigation also reviewed cockpit voice and flight data recorder recordings, though the quality of these recordings was noted as poor.
Findings
- The primary cause of the incident was the careless initiation of engine shutdown procedures too close to the terminal building while the aircraft was practically without brakes.
- A prior collision with a taxiway light at Helsinki-Vantaa had caused a fracture in the left main gear's brake line swivel.
- The resulting hydraulic leak caused the system pressure to drop, rendering the parking brakes ineffective.
- The crew's decision to taxi closer to the terminal, likely to avoid public scrutiny following a recent high-profile runway excursion, contributed to the proximity of the collision.
- The propeller feathering process caused a momentary increase in thrust that the crew could not counteract without functional brakes.