Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Fokker Model F.28 Mark 0070 and Mark 0100 series airplanes, that currently requires revising the Airplane Flight Manual to provide the flightcrew with instructions not to arm the liftdumper system prior to commanding the landing gear to extend. This action would require modification of the grounds of the shielding of the wheelspeed sensor wiring of the main landing gear (MLG) and installation of new electrical grounds for the wheelspeed sensor channel of the anti-skid control box of the MLG. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent electromagnetic interference generated by electrical wiring that runs parallel to the wheelspeed sensor wiring, which could result in inadvertent deployment of the liftdumpers during approach for landing or reduced brake pressure during low speed taxiing, and consequent reduced controllability and performance of the airplane.