Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777-200 and -300 series airplanes equipped with Pratt and Whitney engines. This proposed 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 would require repetitive functional checks for blockage of the forward strut drain line, and doing corrective actions (including cleaning or replacing any blocked drain lines) if necessary; and a one- time cleaning of certain forward strut drain lines. We are proposing 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.