Airworthiness Directives; The Boeing Company Airplanes

We are revising an earlier proposed airworthiness directive (AD) for certain The Boeing Company Model 767-300 and 767-300F series airplanes. The NPRM proposed to require modification and installation of components in the main equipment center. For certain other airplanes, the NPRM proposed to require modification, replacement, and installation of flight deck air relief system (FDARS) components. The NPRM was prompted by reports of malfunctions in the flight deck display units, which resulted in blanking, blurring, or loss of color on the display. This action revises the NPRM by revising the applicability; adding certain modifications; and clarifying certain requirements. We are proposing this supplemental NPRM (SNPRM) to prevent malfunctions of the flight deck display units, which could affect the ability of the flightcrew to read the displays for airplane attitude, altitude, or airspeed, and consequently reduce the ability of the flightcrew to maintain control of the airplane. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.