Summary
This supplemental NPRM revises an earlier proposed airworthiness directive (AD) applicable to Hamilton Sundstrand Propellers model 247F propeller assemblies with certain part number (P/ N) and serial number (S/N) blades. That proposed AD would require removing affected propeller blades from service. That proposed AD resulted from reports of blades with corrosion pits in the tulip area of the blades. This supplemental NPRM revises the proposed AD to remove certain propeller S/Ns from the applicability requirement, and to add additional propeller S/Ns to the applicability requirement. This proposed AD results from the manufacture's latest service information containing propeller S/Ns that were not specified in the proposed AD. We are proposing this AD to prevent cracks from developing in the tulip area of the blade, which could result in separation of the blade and possible loss of airplane control.