What happened
On 2 June 2020, a Cessna U206 Super Skywagon, registered F-HIDZ, was performing a post-maintenance check flight at Gap-Tallard airport. The aircraft had recently undergone a three-year restoration process. During the takeoff roll on runway 20R, the pilot reached a speed of approximately 100 km/h and began the rotation.
As the aircraft rotated, it began banking to the left. The pilot attempted to correct this by turning the control wheel fully to the right. However, due to the reversed configuration of the flight controls, this input amplified the left bank. The aircraft's left wingtip struck the runway, causing the plane to veer from the centerline. The pilot immediately reduced power to "Beta" mode and applied full right rudder, bringing the aircraft to a halt on the left side of the runway. There were no fatalities, though the aircraft sustained substantial damage.
The investigation
The BEA investigation focused on the maintenance history and the installation of the flight control cables. The aircraft had been undergoing a restoration that included a turbine engine conversion. Investigators examined the workshop inspection of the aircraft and discovered that the aileron control cables had been incorrectly routed at the wing bellcranks.
Further examination of the maintenance process revealed that the pilot, who also served as the deputy maintenance manager for the organization, had performed the installation. The investigation also reviewed the company's inspection procedures and the pre-take-off checklists used by the pilot. It was noted that the technician had encountered difficulties interpreting the manufacturer's service manual diagrams and had proceeded with the installation despite uncertainties.
Findings
- The primary cause of the accident was the incorrect routing of the aileron control cables, which resulted in reversed roll control.
- The pilot had misinterpreted the installation diagrams in the service manual while rigging the new cables.
- The maintenance professional performed a self-inspection rather than seeking an independent inspector, partly due to high workload and personnel shortages caused by the COVID-19 pandemic.
- The flight control inspection sheet used during the maintenance did not explicitly require a check of the direction of control surface movement.
- During the pre-take-off checks, the pilot verified that the controls were free but did not visually confirm that the ailerons moved in the correct direction.
- The absence of routing wires (which are typically used to ease cable installation) made the reinstallation process more complex and prone to error.