What happened
On 14 August 2022, a Boeing 737-300F, registration PK-YGV, operated by Tri MG-Intra Asia Airlines, was conducting an unscheduled cargo flight from Jakarta to Banjarmasin. The flight proceeded normally until the approach phase at Syamsudin Noor International Airport.
While descending through 1,200 feet, the crew transitioned the flaps from position 30 to 40. This movement triggered a flap asymmetry, evidenced by the indicator needles splitting—showing approximately 30 degrees on the right side and 10 degrees on the left. The resulting aerodynamic imbalance caused the aircraft to roll toward the left. The crew initiated a go-around and attempted to resolve the issue by recycling the flap lever, but the asymmetry persisted.
After completing the non-normal checklist, the crew proceeded with an ILS approach to Runway 10. Just before touchdown, the aircraft rolled sharply to the left, causing the left wingtip and the left engine cowling to make contact with the runway surface. The pilot successfully leveled the aircraft, completed the landing, and taxied to the apron. There were no injuries to the crew or passengers.
The investigation
The KNKT investigation focused on the mechanical state of the flap system and the maintenance history of the aircraft. Investigators discovered that the flap discrepancy was not an isolated event. During a flight test three days prior to the incident, a similar flap disagreement had been noted and addressed via lubrication of the screw jack and gearbox.
Crucially, the investigation revealed that during a repositioning flight one day before the accident, the pilot had verbally informed an engineer that the flap issue had reoccurred. However, this specific instance was not documented in the Aircraft Flight Maintenance Log (AFML).