What happened
On 23 February 2009, a Boeing McDonnell Douglas MD-90, registered PK-LIO, was operating flight LNI-972 from Medan to Batam when the crew encountered a landing gear malfunction. Shortly after takeoff from Polonial Airport, the pilot observed a red indication on the landing gear panel, signaling that the nose gear was not properly locked. Although the crew successfully cycled the gear to achieve a locked indication during the initial climb, the issue resurfaced during the approach to Hang Nadim Airport.
Upon attempting to extend the landing gear for landing, the nose gear indicator remained red. After several unsuccessful attempts to extend the gear and performing emergency checklists, the pilot in command decided to execute an emergency landing on runway 04 with the nose gear in the up position. To mitigate fire risks, airport emergency services applied foam to the runway prior to arrival. The aircraft touched down and came to a stop on the runway centerline, with the lower fuselage making contact with the pavement. All 162 occupants—including 156 passengers and 6 crew members—evacuated via the forward left escape slide without injury.
The investigation
The investigation focused on why the nose landing gear failed to extend despite the crew's attempts to cycle the system. Investigators examined the wreckage and found that the nose landing gear water spray deflector had fractured and become distorted. This damaged component had shifted into the nose wheel well structure, physically obstructing the extension of the landing gear.
Technical analysis of the deflector revealed a fatigue crack originating from an attachment flange. The fracture surface showed evidence of a pre-existing crack, and investigators noted signs of over-torque on a flange hole edge. Additionally, the low ground clearance of the deflector was noted, suggesting that contact with ground objects during taxi or parking could potentially cause such damage.
Findings
- The primary cause of the gear malfunction was the fracture of the nose landing gear water spray deflector.
- A fatigue crack had developed at the attachment flange of the deflector.
- The structural distortion of the broken deflector moved into the wheel well, creating a mechanical block that prevented the nose gear from descending.
- The aircraft was airworthy and properly maintained at the time of dispatch.