Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to the products listed above. The existing AD currently requires revising the Limitations section of the airplane flight manual (AFM) to advise the flight crew of procedures to follow to ensure that a fuel filter impending bypass condition due to gross fuel contamination is detected in a timely manner. Since we issued that AD, a new design change has been developed that will correct an error in the operating program software (OPS) of the engine indication and crew alerting system (EICAS). This proposed AD would require installing new OPS (Version 7) of the EICAS in the EICAS computers. This proposed AD would also require various concurrent actions, depending on the airplane configuration, including installing a certain EICAS OPS version, making wiring changes, replacing the audio accessory unit, replacing certain handsets and EICAS computers, changing EICAS computer connector keying, and loading Operational Program Configuration (OPC) software. This proposed AD also retains the existing AD provision that relieves certain airplanes (those equipped with certain EICAS OPS versions) from the proposed requirements. Accomplishment of the new proposed actions would terminate the requirements of the existing AD. We are proposing this AD to prevent malfunction and thrust loss on both engines, which could result in a forced off-airport landing.