The incident, involving a Swedish-registered aircraft, took place in August last year but the pilots managed to land the plane safely.
An inquiry by the Air Accidents Investigation Branch into what caused the rolls was inconclusive. It was the second time in three months that the body had looked at an incident involving the plane, which also travelled off a runway after landing in Birmingham in May 2020.
Following the August incident, West Atlantic – which operates the British Aerospace plane – said it had replaced several components and that the same problems had not arisen again.
According to the AAIB report, the aircraft took off towards St Ouen’s Bay and turned north to Guernsey. There was then a sudden jolt before the plane rolled to the left, but the movement was corrected by the autopilot.
There was then a second jolt, which disengaged the aircraft’s autopilot system. The first officer took control of the aircraft and tried turning to the right but found this difficult, as the plane was ‘pushing to the left’, the report said.
In a cockpit voice recording she was heard to say: ‘I’m just giving everything I have to just hold it steady’.
The report added: ‘Extensive testing on the aircraft did not identify the cause but the operator replaced several components as a precautionary measure. Subsequent component testing found no anomalies that could be definitively associated with the incident, although it did identify issues relating to equipment maintenance and testing.’
The report continued: ‘The operator has addressed these through appropriate safety action, and they reported that there had been no recurrences since the aircraft returned to service.’