Flight History
On 20 October 2008, a Boeing 737-400 aircraft, registered PK-MDO, operated by Merpati Nusantara Airlines, was scheduled for passenger service as flight MZ 762 from Sultan Hasanuddin Airport in Makassar, South Sulawesi, to Moses Kilangin Airport in Timika, Papua. The aircraft was on its second sector of the day, having arrived earlier from Jakarta. After a turnaround of about 50 minutes, the crew proceeded with the takeoff roll at 0205 UTC.
During the takeoff roll, the pilot-in-command heard the co-pilot call out “80” knots. At approximately 130 knots, before the “V1” call, the pilot heard a blast noise and the aircraft began to veer to the left. The pilot elected to abort the takeoff, retarding both thrust levers to idle and activating the thrust reversers. As the aircraft decelerated through 80 knots, the co-pilot noted that the speed brake lever had extended and the auto-brake disarm light illuminated. The pilot used rudder pedals to keep the aircraft on the runway centerline. Once the aircraft slowed to normal taxi speed, the pilot turned left onto the runway turning area and intended to taxi back to the apron.
Aircraft and Damage
The aircraft, a Boeing 737-400 with registration PK-MDO, was carrying 172 people: two pilots, five flight attendants, and 165 passengers including nine infants. No injuries to persons were reported. The incident resulted in damage to the aircraft, specifically to the left main wheel assembly. Examination revealed that four of the sixteen bolts on wheel number-1 hub had broken. Fracture surfaces showed fatigue cracks of varying lengths: bolt A (7 mm), bolt B (14 mm), bolt C (11 mm), and bolt D (6 mm). The investigation determined that the wheel failure occurred due to the failure of these bolts.
Investigation Findings
The National Transportation Safety Committee (NTSC) of Indonesia investigated the incident. The analysis of the wheel failure sequence indicated that the bolts had failed due to fatigue, leading to the wheel hub separating from the axle. The investigation also examined the wheel hub load rating and maintenance practices related to wheel management at Merpati Nusantara Airlines. The company’s bolt management procedures were reviewed, and the NTSC identified issues consistent with the bolt failures. The report highlighted that the wheel failure was caused by fatigue cracks in the bolts, but did not assign a specific probable cause in the provided excerpts.
The aircraft was towed to the apron after the incident. The NTSC issued safety recommendations to the airline and the Directorate General of Civil Aviation to address maintenance and inspection procedures for wheel assemblies.