Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Eurocopter France Model SA 330F, G, and J helicopters. This proposal would require verifying the torque on the nut that secures the two transformer-rectifiers' common ground; and subsequently installing a modification to separate the grounds of the two transformer-rectifiers. This proposal is prompted by a report from the airworthiness authority of France about an unsafe condition resulting from the loss of the common ground of the two transformer- rectifiers. The actions specified by the proposed AD are intended to prevent loss of the common ground of the two transformer-rectifiers, which could result in a complete electrical failure (essential and secondary), loss of electrically-powered instrumentation, and subsequent loss of control of the helicopter.