AD FAA-2014-0523

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes equipped with Pratt and Whitney engines. This AD was prompted by reports of blocked drain lines at the engine forward strut that caused flammable fluid to accumulate in a flammable leakage zone. This AD requires repetitive functional checks for blockage of the forward strut drain line and doing corrective actions if necessary, and a one-time cleaning of certain forward strut drain lines. This AD also provides an optional replacement of the drain lines and installation of insulation blankets, and a revision of the maintenance or inspection program, as applicable, to incorporate a certain airworthiness limitation, which would terminate the repetitive checks of the forward strut drain line. We are issuing this AD to detect and correct blockage of forward strut drain lines, which could cause flammable fluids to collect in the forward strut area and potentially cause an uncontrolled fire or cause failure of engine attachment structure and consequent airplane loss.