Airworthiness Directives; Fokker Model F27 Mark 050 Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Fokker Model F27 Mark 050 airplanes. This AD requires doing an initial inspection of the leading edge sections of the elevators to detect loose leading edges and to ensure that there is no gap between the sections and the front spar, and corrective actions if necessary. This AD also requires determining the type of leading edge installed on the elevators. For certain airplanes, this AD requires repetitive inspections until the modification of the leading edge sections of the elevators and the application of sealant, which would end the repetitive inspections. This AD results from reports that the leading edges of the elevators were found loose, although the fasteners were still in place; in one case a stud was broken. In addition, the fastener attachment holes were elongated and worn out, and fretting damage was found on the elevator front spar and balance weights. Investigation revealed that vibration, induced by the propeller slipstream, was the cause of these discrepancies; the stud failure was due to improper installation of the fasteners. We are issuing this AD to prevent jamming, restricting, or binding of the elevators due to loose or missing fasteners, which could make the movement of the elevator difficult and decrease aerodynamic control of the airplane.