Airworthiness Directives; Fokker Model F.28 Mark 0070 and 0100 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F.28 Mark 0070 and 0100 series airplanes, that requires repetitive operational tests for discrepancies of the heating system of pitot tube #1, and replacement of the pitot tube, if necessary. This AD also requires eventual modification of the alternating current sensing circuit for pitot tube #1, which terminates the repetitive operational test requirement. This action is necessary to prevent failure of the heating system of pitot tube #1 due to a short circuit, which may go undetected and lead to the pilot receiving erroneous airspeed indications, resulting in reduced control of the airplane. This action is intended to address the identified unsafe condition.