Airworthiness Directives; BAE Systems (Operations) Limited Model ATP Airplanes; BAE Systems (Operations) Limited Model HS 748 Airplanes

We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: * * * * * Recently, during a walk round check, an operator found an aileron trim tab hinge pin that had migrated sufficiently to cause a rubbing foul on the flap. Other reports indicate that, for the purposes of expediency, it has become common practice during maintenance when replacing a control tab, instead of unbolting the forward part of the piano hinge from the primary control surface, the hinge pins are punched out of the hinges. Investigations have concluded that, after reinserting the pins after maintenance, the ends of the hinges may not have been pinched, which is likely to have been the cause of the detected hinge pin migration. This condition [non-pinched hinge pin ends], if not detected and corrected, could lead to further incidents of migration of a tab hinge pin out of the hinge, likely resulting in restricted movement of the tab control and consequent reduced control of the aeroplane.