Airworthiness Directives; Hamilton Standard 14RF, 247F, 14SF, and 6/5500/F Series Propellers

Resumo

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 action would increase the repetitive inspection interval from 500 to 1,500 hours time in service (TIS) since last inspection for propellers that have a ballscrew quill damper installed. This proposal is prompted by the availability of improved hardware that enhances the lubrication of the BIS and significantly reduces BIS wear. 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.