AD FAA-2006-25079

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Model A310-300 airplanes. This AD requires replacing the existing non-return valve (NRV) of the auxiliary center tanks (ACTs) of the fuel system with a new, improved NRV. This AD results from a report that it was not possible to transfer fuel from ACTs 1 and 2 during flight, and no electronic centralized aircraft monitor warnings were triggered. Investigation revealed a faulty static inverter and blown fuse, resulting in failure of certain fueling bus bars and subsequent failure of the automatic ACT fuel transfer. We are issuing this AD to prevent these failures, combined with failure of the NRV to close. If the NRV is open during flight, the fuel supply to the engines may be reduced during cross-feed operation to the extent that fuel starvation could occur and result in engine flameout.