A Cessna 404 Titan aircraft was engaged in low level geophysical survey work near Tennant Creek, NT. The pilot reported that as he was manoeuvring the aircraft at the completion of a survey run, he became aware that the aircraft's response to aileron control input was reduced. He was able to roll the aircraft to wings level attitude using a combination of aileron and rudder, before climbing the aircraft to approximately 6,000 ft and returning to Tennant Creek aerodrome.
Examination of the aileron control system by company maintenance personnel revealed that one of the aileron cables had separated near a change of direction pulley below the control pedestal in the cockpit. Company maintenance personnel reported that there were no obvious signs of fatigue or wear at the failure point and that the reason for the failure was not immediately apparent. The cable could not be identified by manufacturer or part number.
The aircraft had undergone a routine scheduled maintenance inspection 29 hours prior to the event. The engineer reported that it was difficult to inspect the cable in the area beneath the control pedestal during normal scheduled inspections. It was suggested that the only way to adequately examine it would be to disconnect and remove it in accordance with the manufacturers major maintenance requirements.
The aircraft logbooks showed that the aircraft was manufactured in 1981, and had been imported into Australia from Indonesia. At the time of the occurrence, it had a total time in service of 3,853 hours. The aircraft logbooks did not indicate any previous replacement of the aileron cable.
The maintenance engineer advised that, following the incident, he submitted the cable and a detailed major defect report to the local CASA office. CASA Airworthiness advised that their examination was not able to identify the reason for the failure with any certainty. They confirmed that there were no serial or part numbers on the cable and that it was probably not the correct specification for this type of installation. The most likely scenario was that the cable was manufactured and fitted to the aircraft in Indonesia.