AWD 767

SUMMARY: We are revising an earlier proposed airworthiness directive
(AD) for certain The Boeing Company Model 767 airplanes. That NPRM
proposed to require drilling a drain hole in the flanged tubes for
certain elevator control cable aft pressure seals; doing repetitive
inspections for dirt, loose particles, or blockage of the flanged tube
and drain hole for the pressure seals, and corrective action if
necessary; replacing the aft air-intake duct assembly with a new or
modified assembly and installing a dripshield; and installing gutters
on the horizontal stabilizer center section and modifying the side
brace fittings. That NPRM was prompted by reports of stiff operation of
the elevator pitch control system and jammed elevator controls. This
action revises that NPRM by proposing to require replacement of
pressure seal assemblies, rather than the proposed drilling of drain
holes; revising a certain compliance time and inspection type; adding
certain optional actions; and revising the applicability. We are
proposing this supplemental NPRM to prevent moisture from collecting
and freezing on the elevator control system components, which could
limit the ability of the flightcrew to make elevator control inputs and
result in reduced controllability of the airplane.