AAIB investigation to Cessna Citation CJ1+, N680KH
Uncommanded roll after departure, Bournemouth Airport, 13 April 2019.
Summary:
The aircraft had been modified with a system intended to enhance its performance, which included supplementary control surfaces designed to deflect symmetrically and automatically to alleviate gust loads. Shortly after takeoff, an electrical failure in this system caused one of these control surfaces to deploy separately, causing an uncommanded roll. The resulting aircraft upset caused the pilot significant surprise and difficulty in controlling the aircraft.
The pilot was not aware of supplementary procedures associated with the modification. The procedures did not adequately characterise the significance of the system failure, nor address the failure in all anticipated flight conditions. Certification flight tests of the system did not reveal the severity of possible outcomes. The ‘Aircraft Safety and Certification Reform Act 2020’ underway in the USA will review existing assumptions on pilot recognition and response.
Four Safety Recommendations are made, and safety action has been taken or is intended in the areas of training and the information to be provided, both for this system and for other supplementary systems capable of influencing the flight path of an aircraft.
Download report:
Safety Recommendation document: