AD NUMBER: 2006-16-05
MANUFACTURER: Pratt & Whitney
SUBJECT: Airworthiness Directive 2006-16-05
SUMMARY: The FAA is superseding an existing
airworthiness directive (AD) for Pratt & Whitney PW4164,
PW4168, and PW4168A series turbofan engines.
That AD currently requires initial and repetitive torque checks
for loose or broken front pylon mount bolts made from INCO 718
material and MP159 material, and initial and repetitive visual
inspections of the primary mount thrust load path.
This AD requires the same actions, but at reduced intervals for
front pylon mount bolts made from MP159 material. This AD results
from analysis by the manufacturer that the MP159 material pylon
bolts do not meet the full life cycle torque check interval
requirement, in a bolt-out condition.
We are issuing this AD to prevent front pylon mount bolt and
primary mount thrust load path failure, which could result in an
engine separating from the airplane.