AD 2000-04-20 Amendment 39-11603

This amendment adopts a new airworthiness directive (AD), applicable to Bell Helicopter Textron Canada (BHTC) Model 407 helicopters, that requires replacing a certain hydraulic relief valve (valve) with a different valve. This amendment is prompted by the discovery of a manufacturing defect in a valve. The actions specified by this AD are intended to prevent intermittent loss of hydraulic pressure to the flight controls and subsequent loss of control of the helicopter.