What happened
On November 27, 2008, a Beech Sundowner C-23, registration PK-ANX, was conducting a solo training flight operated by the Indonesia Civil Aviation Institute. The aircraft landed on runway 22L at Budiarto Airport under crosswind conditions of 12 knots.
During the landing roll, the student pilot experienced intense vibrations originating from the nose wheel. In an attempt to maintain directional control, the pilot attempted to use the rudder pedals. However, the pilot's seat unexpectedly slid backward along its track. This movement prevented the pilot from effectively reaching or operating the rudder pedals, leading to a loss of directional control. The aircraft eventually came to a stop approximately 929 meters from the end of the runway. The student pilot escaped the aircraft without injury, though the aircraft sustained substantial damage, including a broken nose wheel, a dented propeller, and a broken engine cowling.
The investigation
The investigation into the accident focused on two primary mechanical failures: the nose wheel vibration and the seat'unsecured movement.
Investigators examined the nose wheel assembly and discovered that the shimmy damper was non-functional due to a hydraulic leak. This failure prevented the component from absorbing the vibrations during the landing roll.
Regarding the cockpit environment, the investigation scrutinized the pilot's seat adjustment mechanism. It was determined that the seat's locking pin had not been correctly inserted into the track. The investigation found that the locking handle's mechanism was worn, which allowed the pin to appear engaged when it was actually loose. As the vibrations from the nose wheel occurred, the seat shifted rearward, physically obstructing the pilot's ability to manipulate the flight controls.
Findings
- The aircraft was undergoing a solo training flight at the time of the incident.
- The shimmy damper was leaking hydraulic fluid, which failed to mitigate nose wheel vibrations.
- The pilot seat was not properly secured in the track prior to takeoff.
- The locking mechanism for the seat was worn, preventing the pin from being properly seated in the rail.