Summary
This document revises an earlier proposed superseding airworthiness directive (AD) for the specified Eurocopter France (ECF) model helicopters. That AD currently requires certain checks of the magnetic chip detector plug (chip detector) and the main gearbox (MGB) oil-sight glass, certain inspections of the lubrication pump (pump), and replacing the MGB and the pump with an airworthy MGB and pump, if necessary. Also, the AD requires that before a pump or MGB with any hours time-in-service (TIS) can be installed, it must meet the AD requirements. The earlier proposed superseding AD proposed retaining those requirements but proposed adding all serial-numbered pumps to the applicability. This supplemental proposal is prompted by an improved procedure for detecting oil pump wear earlier and is considered more accurate than the procedure proposed previously. The actions specified by the proposed AD are intended to implement improved procedures to detect a failing MGB oil pump, to prevent failure of the MGB pump, seizure of the MGB, loss of drive to an engine and main rotor, and subsequent loss of control of the helicopter.