G-PRPC EW/C2016/12/03 Following overnight maintenance work, the outboard engine access panel on the No 1 engine was incorrectly latched shut. This was not identified by the engineer completing the task, by the flight crew during the subsequent pre-departure inspection, or by the ground operations personnel dispatching the aircraft. During takeoff the panel failed at the hinge attachment points and departed the aircraft, striking and damaging the vertical stabiliser, before coming to rest on the runway and its grass verge. A previous incident, where the same engine panel was lost during takeoff, had occurred on the aircraft a month earlier. This report addresses both incidents. Safety action has been taken by the aircraft manufacturer to add labelling and amend the Aircraft Maintenance Manual (AMM), and the operator has revised its maintenance procedures. In addition, two Safety Recommendations have been made relating to flight crew pre-departure inspection procedures and dissemination of safety information to ground crew.