Airworthiness Directives; The Enstrom Helicopter Corporation Model F-28A, F-28C, F-28C-2, 280, and 280C Series Helicopters

摘要

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to The Endstrom Helicopter Corporation Model F-28A, F-28C, 280, and 280C series helicopters, that currently requires an initial and repetitive visual inspections of the upper swashplate bearings for corrosion, and replacement of defective upper swashplate bearings with airworthy bearings. This action would require that the visual inspections apply to both the upper and lower swashplate bearings (bearings); expand the applicability to those affected helicopters manufactured prior to January 1, 1981; establish a retirement life of 1,200 hours' time-in-service for certain bearings; and provide a corrected upper swashplate bearing part number. This proposal is prompted by the necessity to require visual inspection so the lower swashplate bearings; expand the applicability to include the Model F-28C-2 helicopter; establish a retirement life for certain bearings; and correct the upper swashplate bearing part number from the existing AD. The actions specified by the proposed AD are intended to prevent failure of the bearings and subsequent loss of control of the helicopter.