What happened
On 16 November 2016, a Cessna 172P, registration PK-NIZ, was conducting touch-and-go flight training at Adi Soemarmo Airport, Indonesia. During the fifth touch-and-go maneuver, the aircraft experienced significant vibration immediately after the nose wheel made contact with the runway. The flight instructor took control of the aircraft, increasing engine power and maintaining a nose-up attitude to minimize the load on the nose gear.
As the aircraft proceeded along the runway toward taxiway C, a pilot of another aircraft observed the plane rolling with a high nose attitude and no nose wheel visible. The crew eventually lowered the nose and brought the aircraft to a stop. There were no injuries among the crew or students, though the aircraft sustained minor damage.
The investigation
The investigation focused on the nose landing gear assembly following the discovery of detached components on the runway. Investigators located the axle stud, castellated nut, and nose wheel at various points along the runway and taxiway area.
Examination of the hardware revealed that while one end of the axle stud remained secured with a nut and cotty pin, the other end was missing its nut and pin. The investigation also noted that the nose wheel assembly had undergone maintenance just eight days prior to the incident to repair a hydraulic leak, which involved the removal and reinstallation of the nose wheel. No documentation of this specific repair was found in the maintenance log book.
Findings
- The primary cause of the nose wheel detachment was the loosening and eventual detachment of the castellated nut from the axle stud.
- This loosening was caused by the absence of a cotter pin, which is essential for securing the nut in place.
- The missing cotter pin may have resulted from it not being installed during the recent nose wheel maintenance or from the use of a reused pin that subsequently fractured.
- The lack of maintenance records for the recent nose wheel repair prevented verification of the installation procedures used.