Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Hamilton Standard 14RF, 247F, 14SF, and 6/5500/F (formerly Hamilton Standard/British Aerospace 6/5500/F) series propellers, that currently requires initial and repetitive inspections of the propeller control unit (PCU) servo ballscrew internal spline (BIS) teeth for wear, and replacement, if necessary, of PCU servo BIS assemblies. This proposed AD would increase the repetitive PCU servo BIS teeth inspection interval from 1,500 to 2,500 hours time in service (TIS) for propellers that have a ballscrew quill damper installed. In addition, this proposed AD would add an optional terminating action to the repetitive PCU servo BIS teeth inspections by installing a Secondary Drive Quill (SDQ). If an SDQ is installed, this proposed AD would require initial and repetitive torque check inspections of the primary ballscrew quill. This proposal is prompted by field service and laboratory test data that indicate that the repetitive inspection interval can be safely increased, and by the development and availability of the SDQ. The actions specified by the proposed AD are intended to prevent inability to control the propeller blade angle due to tooth wear in the PCU servo BIS assembly.