Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain EMBRAER Model EMB-120 series airplanes that would have required initial and repetitive calibration testing of potentiometers to detect noisy signals and replacement of only those with noisy signals. This new action revises the proposed AD by reducing the compliance time for the repetitive calibration testing of the potentiometers and adding the requirement for reporting results of the calibration tests of the potentiometers and the readouts of the flight data recorder (FDR) to the airplane manufacturer. The actions specified by this new proposed AD are intended to prevent the potentiometers that provide information on the positions of the primary flight controls to the FDR from transmitting noisy signals or becoming improperly calibrated, resulting in the transmission of incomplete or inaccurate data to the FDR. This lack of reliable data could hamper discovery of the unsafe conditionthat caused an accident or incident and prevent the FAA from developing and mandating actions to prevent additional accidents or incidents caused by that same unsafe condition. This action is intended to address the identified unsafe condition.