Airworthiness Directives; Eurocopter France Model AS355E, F, F1, F2, and N Helicopters

Résumé

This document proposes to revise an existing 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 an MGB or pump with any time-in-service (TIS) can be installed, it must meet the AD requirements. This action would retain those requirements but would limit the applicability to one part number with certain serial-numbered pumps or modified after a certain date. This proposal was prompted by an investigation by the manufacturer that revealed a malfunction occurred after modifying the pump case on certain pumps after major overhaul and repairs. The actions specified by this AD are intended to limit the applicability to certain pumps, to detect sludge on the chip detector, 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.