What happened
On 12 August 2007, a Jeju Air DHC-8-402, registration HL5256, was performing a scheduled domestic flight from Jeju International Airport to Gimhae International Airport. During the landing roll on runway 18R, the aircraft lost directional control and drifted toward the left side of the runway. The aircraft subsequently exited the paved surface and collided with a concrete drainage ditch. The incident resulted in 4 injuries to passengers and caused substantial damage to the aircraft.
During the flight, the crew had observed various caution lights, including rudder control and hydraulic warnings, at higher altitudes. While the pilots performed procedures from the Quick Reference Handbook (QRH), they did not identify a critical loss of rudder effectiveness. Upon touchdown, the aircraft began drifting into the wind. Despite attempts to use the rudder pedals and control wheel to maintain the centerline, the rudder failed to respond to pilot inputs. As the aircraft left the runway, no effective alternative measures were taken to correct the direction.
The investigation
The ARAIB examined the flight data recorder (FDR) and cockpit voice recorder (CVR) to reconstruct the sequence of events. The investigation focused on the aircraft's flight control electronic control system (FCECU) and the crew's response to cockpit warnings. Investigators also reviewed maintenance records, specifically regarding a previous lightning strike and the handling of non-volatile memory (NVM) fault codes. Additionally, the physical layout of the airfield, including the location of the drainage ditch, was evaluated.
Findings
- The rudder failed to respond to the pilots' rudder pedal inputs during the landing roll.
- The crew did not recognize the rudder malfunction during the flight or during the landing phase.
- No appropriate alternative measures were implemented to control the aircraft's direction after it departed the runway.
- The crew did not confirm abnormal indications for the rudders and spoilers through specific verification procedures.
- The existing QRH lacked clear instructions regarding the possibility of a total loss of rudder response when certain caution lights were illuminated.
- Maintenance discrepancies were noted regarding the documentation of a lightning strike and the resetting of fault codes.
- The drainage ditch involved in the collision was located outside the prescribed safety range for runway 18R.